Diabetes Diet

February 2002

WHAT IS DIABETES?

The two major forms of diabetes are type 1 (previously called insulin-dependent diabetes mellitus (IDDM) or juvenile-onset diabetes) and type 2 (previously called noninsulin-dependent diabetes mellitus (NIDDM) or maturity-onset diabetes). [For more details, see the Well Connected Report #9, Diabetes Type 1 and Report #60, Diabetes Type 2 .]

Insulin

Both diabetes type 1 and type 2 share one central feature: elevated blood sugar ( glucose) levels due to absolute or relative insufficiencies of insulin, a hormone produced by the pancreas. Insulin is a key regulator of the body's metabolism. It normally works in the following way:

During and immediately after a meal the process of digestion breaks carbohydrates down into sugar molecules (of which glucose is one) and proteins into amino acids.
Right after the meal, glucose and amino acids are absorbed directly into the bloodstream, and blood glucose levels rise sharply. (Glucose levels after a meal are called postprandial levels.)
The rise in blood glucose levels signals important cells in the pancreas, called beta cells , to secrete insulin, which pours into the bloodstream. Within ten minutes after a meal insulin rises to its peak level.
Insulin then enables glucose and amino acids to enter cells in the body, particularly muscle and liver cells. Here, insulin and other hormones direct whether these nutrients will be burned for energy or stored for future use. (It should be noted that the brain and nervous system are not dependent on insulin; they regulate their glucose needs through other mechanisms.)
When insulin levels are high, the liver stops producing glucose and stores it in other forms until the body needs it again.
As blood glucose levels reach their peak, the pancreas reduces the production of insulin.
About two to four hours after a meal both blood glucose and insulin are at low levels, with insulin being slightly higher. The blood glucose levels are then referred to as fasting blood glucose concentrations .

Type 1 Diabetes

In type 1 diabetes, the disease process is more severe that type 2 diabetes and onset is usually in childhood:

Beta cells in the pancreas that produce insulin are gradually destroyed. Eventually insulin deficiency is absolute.
Without insulin to move glucose into cells, blood glucose levels become excessively high, a condition known as hyperglycemia.
Because the body cannot utilize the sugar, it spills over into the urine and is lost.
Weakness, weight loss, and excessive hunger and thirst are among the consequences of this "starvation in the midst of plenty."
Patients become dependent on administered insulin for survival.

Dietary control in type 1 diabetes is very important and must focus on balancing food intake with insulin intake and energy expenditure from physical exertion. [ See Well-Connected Report #9 , Diabetes: Type 1. ]

Type 2 Diabetes

Type 2 diabetes is most common form of diabetes, accounting for 90% of cases. An estimated 16 million Americans have type 2 diabetes and half are unaware they have it. The disease mechanisms in type 2 diabetes are not wholly known, but some experts suggest that it may involve the following three stages in most patients: first stage in type 2 diabetes is the condition called insulin resistance; although insulin can attach normally to receptors on liver and muscle cells, certain mechanisms prevent insulin from moving glucose (blood sugar) into these cells where it can be used. Most type 2 diabetics produce variable, even normal or high, amounts of insulin, and in the beginning this amount is usually sufficient to overcome such resistance.
Over time, the pancreas becomes unable to produce enough insulin to overcome resistance. In type 2 diabetes, the initial effect of this stage is usually an abnormal rise in blood sugar right after a meal (called postprandial hyperglycemia). This effect is now believed to be particularly damaging to the body.
Eventually, the cycle of elevated glucose further impairs and possibly destroys beta cells, thereby stopping insulin production completely and causing full-blown diabetes. This is made evident by fasting hyperglycemia, in which elevated glucose levels are present most of the time.

Obesity is common in type 2 diabetics and this condition appears to be related to insulin resistance. The primary dietary goal for overweight type 2 patients is weight loss and maintenance. Studies indicate that when people with type 2 diabetes can maintain intensive exercise and diet modification programs, many can minimize or even avoid medications. [ See Well-Connected Report # 60 , Diabetes: Type 2. ]

WHAT ARE THE GENERAL GUIDELINES FOR A DIABETES DIET?

General Dietary Goals for People with Diabetes

The treatment goals for a diabetes diet are the following:

To achieve near normal blood glucose levels. People with type 1 diabetes or type 2 diabetes who are on insulin or oral medication must coordinate calorie intake with medication or insulin administration, exercise, and other variables to control blood glucose levels.
To protect the heart and aim for healthy lipid (cholesterol and triglyceride) levels and control of blood pressure.
To achieve reasonable weight. Overweight type 2 diabetics who are not taking medication should aim for a diet that controls both weight and glucose. A reasonable weight is usually defined as what is achievable and sustainable, rather than one that is culturally defined as desirable or ideal. Children, pregnant women, and people recovering from illness should be sure to maintain adequate calories for health.
To manage or prevent complications of diabetes. People with diabetes, whether type 1 or 2, are at risk for a number of medical complications, including heart and kidney disease. Dietary requirements for diabetes must take these disorders into consideration.
To promote overall health.

Overall Guidelines. There is no longer a single diabetes diet that will suit everyone. The overall approach is based on the US Dietary Guidelines for healthy eating for all Americans, and includes the following:

Limit fats. Avoid saturated fats (found in animal products) and trans-fatty acids (hard margarines, commercial products, fast foods). In selecting fats or oils, prefer monounsaturated fats (virgin olive oil, canola oil), although also include polyunsaturated oils as well (sunflower, rapeseed). Of note, a 2001 report suggested that trans-fatty acids were a risk factor for diabetes type 2 while polyunsaturated were protective.
Limit dietary cholesterol.
Consume plenty of fiber-rich foods in the form of whole grains and fresh fruits and vegetables. Includes a daily choice of nuts, seeds, or legumes.
When choosing foods with sugar, choose fresh fruits, but do so in moderation.
Limit protein. In selecting proteins, eat in moderation and prefer fish or soy protein to poultry or meat. (Avoid, in any case, high-fat meats.)
Reduce salt.

Furthermore, the American Diabetes and Dietetic Association recommends a balanced meal plan for diabetes that uses the following ratios:

Protein providing 15% to 20% total calories
Fat providing no more than 30% (with saturated fats being no more than 10%), and
Carbohydrates supplying up to 60%.

In general, everyone should aim for five servings of fruits and vegetables and six servings of whole grains each day and two weekly servings of fatty fish.

Some Specific Diets for People with Diabetes

Patients ideally should meet with a professional dietitian to plan an individualized diet within the general guidelines that takes into consideration their own health needs. There is no single diet that meets all the needs of everyone with diabetes. For instance, a type 2 diabetic who is overweight and insulin-resistant may need to have a different carbohydrate-protein balance than a thin type 1 diabetic in danger of kidney disease.

Healthy eating habits along with good control of blood glucose are the basic goals in managing this complex disease, and several good dietary methods are available to meet them:

A simple heart-healthy diet with weight control may be sufficient for people with type 2 diabetes. One study of people with type 2 diabetes compared several diet plans: a high-carbohydrate/high-fiber diet, a low-fat diet, and a weight management diet. After 18 months all groups experienced similar and improved glycolated hemoglobin and cholesterol levels. The researchers concluded that the positive benefits of the diets were derived not from the specific regimens, but because the people in the study were attentive and focused. In other words, any healthy diet works if patients work at it.
Intricate dietary methods are available for control of blood sugar in type 1 and more severe type 2 diabetes. The most common method for controlling blood sugar is the use of The Diabetic Exchange Lists. More sophisticated methods include counting carbohydrate grams and using the so-called glycemic index to determine the impact of carbohydrates on blood sugar.

If one of these approaches works in controlling glucose levels, there is no reason to choose another. Each of them can be effective, but because regulating diabetes is an individual situation, everyone with this condition should get help from a dietary professional in selecting the best method.

Monitoring

Tests for Glucose Levels. Both hypoglycemia and hyperglycemia are of concern for patients who are receiving insulin. It is important, therefore, to monitor blood glucose levels carefully. Patients should aim for the following measurements:

Pre-meal glucose levels of between 80 and 140 mg/dL.
Bedtime levels of between 100 and 160.

In general, patients who are tightly controlling glucose levels need to take readings four or more times a day. Blood glucose levels are generally more stable in type 2 diabetes than in type 1, so experts usually recommend measuring blood levels only once or twice a day. Different goals may be required for specific individuals, including pregnant women, very old and very young people, and those with accompanying serious medical conditions.

Tests for Glycosylated Hemoglobin. Another test examines blood levels glycosylated hemoglobin , also known as hemoglobin A1c (HbA1c). Measuring glycosylated hemoglobin is not currently used for an initial diagnosis, but it may be useful for determining the severity of diabetes. The test is not affected by food intake so it can be taken at any time. A home test has been developed that might make it easier to measure HbA1c. In general, measurements suggest the following:

Normal HbA1c levels should be below 7%.
Levels of 11% to 12% glycolated hemoglobin indicate poor control of carbohydrates. High levels are also markers for kidney trouble.

Other Tests. Other tests are needed periodically to determine potential complications of diabetes, such as high blood pressure, unhealthy cholesterol levels, and kidney problems. Such tests may also indicate whether current diet plans are helping the patient and whether changes should be made. Annual urine tests showing even microscopic traces of a protein known as albumin can also indicate a future risk for serious kidney disease.

Preventing Hypoglycemia (Insulin Shock)

For prevention of long-term complications of diabetes, experts are now recommending that both type 1 and type 2 patients should aim at keeping blood levels as close to normal as possible. Such intensive insulin treatment increases the risk of hypoglycemia, which occurs when blood sugar is extremely low (below 60 mg/dl). The following tips may help avoid hypoglycemia or prepare for attacks.

Patients are at highest risk for hypoglycemia at night. Bedtime snacks may be helpful.
Patients who intensively control their blood sugar should monitor blood levels as often as possible, four times or more per day. This is particularly important for patients with hypoglycemia unawareness.
In adults, it is also particularly critical to monitor blood glucose levels before driving, when hypoglycemia can be very hazardous.
Diabetic patients on therapies that put them at risk for hypoglycemia should always carry hard candy, juice, sugar packets, or commercially available glucose substitutes designed for diabetic individuals.

Other Factors Influencing Diet Maintenance

Food Labels. Every year thousands of new foods are introduced, many of them advertised as nutritionally beneficial. It is important for everyone, most especially people with diabetes, to be able to differentiate advertised claims from truth. The current food labels show the number of calories from fat, the amount of nutrients that are potentially dangerous (fat, cholesterol, sodium, sugars) as well as useful nutrients (fiber, carbohydrates, protein, vitamins).

Labels also show "daily values," the percentage of a daily diet that each of the important nutrients offers in a single serving. Unfortunately, the daily value is based on 2,000 calories, generally much higher than most diabetics should have, and the serving sizes may not be equivalent to those on the Exchange Lists. Most people will need to recalculate the grams and calories listed on food labels to fit their own serving sizes and calorie needs.

Weighing and Measuring. Weighing and measuring food is extremely important in order to get the correct number of daily calories.

Along with measuring cups and spoons, choose a food scale that measures grams. (A gram is very small, about 1/28th of an ounce.)
Food should be weighed and measured after cooking.
After measuring all foods for a week or so, most people can make fairly accurate estimates by eye or by holding food without having to measure everything every time they eat.

Timing. Meals should not be skipped, particularly for those who are on insulin. Skipping meals can upset the balance between food intake and insulin and also can lead to weight gain if the patient eats extra food too often to offset low blood sugar levels.

The timing of meals is particularly important for people taking insulin:

Patients should coordinate insulin administration with calorie intake. In general, they should eat three meals each day at regular intervals. Snacks are often required.
They should try to take an insulin injection 30 minutes before they eat, although this timing could vary, depending on the form. Some experts recommend a fast acting insulin (insulin lispro) at each meal and a longer (basal) insulin at night.

WHAT ARE THE MAJOR FOOD COMPONENTS IN A DIABETES DIET?

Carbohydrates

Compared to fats and protein, carbohydrates have the greatest impact on blood sugar. Evidence now suggests that it is the total amount of carbohydrates rather than the specific type that most directly affects blood glucose. Carbohydrate types are either complex (as in starches) or simple (as in fruits and sugars). One gram of carbohydrates equals four calories. The current general recommendation is that carbohydrates should provide between 50% and 60% of the daily caloric intake.

Complex Carbohydrates. In all cases, complex carbohydrates found in whole grains and vegetables are preferred over those found in starch-heavy foods, such as pastas, white-flour products, and potatoes. In one study, substituting special starch-free bread for normal bread resulted in a significant decline in blood glucose and hemoglobin A1c in type 2 diabetes. Complex carbohydrates are also the main source of fiber, which is extremely important in any health diet. [ See Box Fiber.] People with diabetes should also prefer complex carbohydrates that have a low glycemic index and are high in fiber. Generally, this means whole grains. [ See Table The Glycemic Index of Some Foods.]

Fiber

Fiber is an important component of many complex carbohydrates. It is almost always found only in plants, particularly vegetables, fruits, whole grains, nuts, and legumes (beans and peas). (One exception is chitosan, a dietary fiber made from shellfish skeletons.) Fiber cannot be digested but passes through the intestines, drawing water with it and is eliminated as part of feces content. The following are specific advantages from high-fiber diets (up to 55 grams a day):

Studies suggest that diets rich in fiber from whole grains reduce the risk for type 2 diabetes. Sources include whole grain breads, brown rice, and bran.
Insoluble fiber (found in wheat bran, whole grains, seeds, nuts, and fruit and vegetables) may help achieve weight loss. (It should be noted that nuts may be particularly beneficial for the heart by lowering LDL and total cholesterol without increasing triglycerides.)
Soluble fiber (found in dried beans, oat bran, barley, apples, citrus fruits, and potatoes), has important benefits for the heart, particularly for achieving healthy cholesterol levels and possibly benefiting blood pressure as well. Simply adding breakfast cereal to a diet appears to reduce cholesterol levels. A new form of barley may have three times the soluble fiber as oats and, in one study, was more effective than oats in controlling blood glucose and insulin. People who increase their levels of soluble fiber should also increase water and fluid intake.

Fiber supplements, such as Metamucil, Fiberall, and Perdiem do not appear to achieve the same benefits as foods naturally high in soluble fiber. Glucomannan, a natural high fiber powder obtained from a root, however, is showing promise in helping control blood glucose levels, cholesterol, and blood pressure.

Simple Carbohydrates (Sugar). No difference appears to exist between complex carbohydrates and simple sugars in their ability to raise blood glucose levels and in diets. The recent evidence on carbohydrates does not mean that diabetics should overload on sugar. However, people with diabetes can now add sugar (ideally from fresh fruits) in higher amounts than previously thought.

Sugars are general one of two types:

Sucrose (table sugar). Sucrose has also been associated with higher triglycerides and harmful cholesterol levels. And a 2002 study suggested that a high level of sugar consumption may reduce levels of HDL cholesterol, the so-called good cholesterol.
Fructose (sugar molecule found in fruits). Fructose may produce a slower increase in glucose than sucrose. And a 2001 study reported that low-dose fructose boosted the ability to process glucose in the liver, an effect that could help people with poorly controlled blood glucose. (As with any sugar, however, excess use of fructose is associated with triglycerides and harmful cholesterol levels.)

Sugar itself, either as sucrose or fructose, adds calories, increases blood glucose levels quickly, and provides no other nutrients. People with diabetes should continue to avoid products listing more than 5 grams of sugar per serving, and even fruit intake should be moderate. If specific amounts are not listed, patients should avoid products with either sucrose or fructose listed as one of the first four ingredients on the label. [ See Box Artificial Sweeteners.]

Artificial Sweeteners

Artificial sweeteners include the following:

Saccharin (Sugar Twin, Sweet n'Low, Sucaryl, and Featherweight). Some previous studies found that large amounts of saccharin cause bladder cancer in rats, but the rats were fed huge amounts that do not apply to human diets. (Nevertheless, evidence suggests that those who have six or more servings per day may have an increased risk.)
Aspartame (Nutra-Sweet, Equal, NutraTase). Aspartame has come under scrutiny because of rare reports of neurologic disorders, including headaches or dizziness, associated with its use. It has been studied more intensively than any other food additive, however, and concern about any major health dangers is unfounded.
Sucralose (Splenda). Sucralose has no better aftertaste and works well in baking, unlike other artificial sweeteners.
Acesulfame-potassium (Sweet One and SwissSweet)
under consideration for approval include neotame and alitame, which are made from amino acids.

Protein

In general, experts recommend that proteins should provide 12% to 20% of calories. Some believe that anyone with diabetes other than pregnant women should restrict protein to about 0.4 grams for every pound of their ideal body weight, about 10% of daily calories. One gram of protein contains four calories. Protein is commonly recommended as part of a bedtime snack to maintain normal blood sugar levels during the night, although studies are mixed over whether it adds any protective benefits against nighttime hypoglycemia. If it does, only small amounts (14 grams) may be needed to stabilize blood glucose levels.

Reducing proteins may help slow the progression of kidney disease, and one 1999 study indicated that a strict-low protein diet may even delay the need for dialysis in patients with kidney failure. (It should be noted that a diet that is severely low in both protein and salt diet while coupled with high fluid intake increases the risk for hyponatremia, a rare condition that can cause fatigue, confusion, and, in extreme cases, can be life-threatening.)

Fish. Fish is still probably the best source of protein. It has many advantages:

In one study, fish protein protected rats on high-fat diets against insulin resistance, while plant protein had no effect.
A number of studies have reported that eating fish or shellfish at least once a week reduces the risk of sudden death from dangerous heart-rhythm abnormalities by more than one half. Oily fish that are high in omega-3 fatty acids, such as salmon, halibut, swordfish, and tuna, are particularly beneficial.

At this time, most studies indicate that eating moderate amounts (one or two servings weekly) of fish offers the most benefits. Some studies found that very high amounts (five or six servings weekly) can be harmful. This risk may be due to the presence of mercury in many kinds of fish.

Soy. Soy is an excellent food:

It is rich in both soluble and insoluble fiber, omega-3 fatty acids, and provides all essential proteins.
Soybeans also contain natural estrogens called isoflavones, which have positive effects on lipid levels.
A number of studies have indicated that subjects that consume about 40 grams of soy protein each day reduce LDL by 13%, triglycerides by 11%, and increase HDL by 2%.

Four ounces of tofu equals about eight to 13 grams of soy, and a soy burger contains about 18 grams. Powdered soy protein that contains at least 60 mg of isoflavones may provide similar benefits. Tablets of individual isoflavones found in soy, however, do not appear to offer any advantages. (Note: soy sauce contains only a trace amount of soy and is very high in sodium.) Of possible concern, a high intake of soy during pregnancy may have some adverse effect on the fetus, although only animal studies have suggested this. More research is important.

Meat. For heart protection, one 1999 study suggested that it didn't matter if you chose fish, poultry, beef, or pork as long as the meat was lean. (Saturated fat in meat is the primary danger to the heart.) The fat content of meat varies depending on the type and cut. It is best to eat skinless chicken or turkey; the leanest cuts of pork (loin and tenderloin), veal, and beef are nearly comparable to chicken in calories and fat in their effect on LDL and HDL levels. It should be noted, however, that even chicken and lean meat do not improve cholesterol levels, and, in terms of cardiac health, fish is a more desirable choice.

Fats and Oils

General Recommendations for Fat Intake. About two-thirds of cholesterol in the body does not come from cholesterol in food but is manufactured by the liver, its production stimulated by saturated fat (mostly found in animal products). The dietary key to managing cholesterol, then, lies in understanding fats and oils. When it comes to studying the effects of fat on the body, however, the problem is compounded by its complex nature. All fats and oils found in foods are made up of chains of molecules composed of carbon and glycerol called fatty acids and which are bound by hydrogen atoms. There are three major chains:

Monounsaturated fatty acids. One pair of carbon atoms is missing hydrogen bonds. Found in plant products.
Polyunsaturated fatty acids. Two or more pairs of carbon atoms are missing hydrogen bonds. Found in plant products.
Saturated fatty acids. All carbon atoms have the maximum hydrogen bonds. Found in animal products.

The oils and fats that people and animals eat are nearly always mixtures of all three fatty acids, but one type usually predominates.

In addition, there are three chemical subgroups of polyunsaturated fatty acids called essential fatty acids: they are the following:

omega-3 and omega-6 polyunsaturated fatty acids, and
omega-9 monounsaturated fatty acids.

To complicate matters, there are also trans-fatty acids. Most of these are not natural fats but are manufactured by adding hydrogen atoms, a process known as hydrogenation, to polyunsaturated fatty acids. These subgroups are being heavily researched for their specific effects on health.

All fats, both good ones and bad, add the same calories. In order to calculate daily fat intake, multiply the number of fat grams eaten by nine (one fat gram is equal to 9 calories, whether it's saturated or unsaturated) and divide by the number of total daily calories desired. One teaspoon of oil, butter, or other fats equals about five grams of fat.

Although there is much controversy on the overall effects of fat on health, virtually all experts strongly advise limiting intake of saturated fats and trans-fatty acids (found in hard margarine, commercial baked goods, and fast foods). Other fatty acids, however, appear to offer benefits.

Harmful Fats. Reducing consumption of saturated fats and trans-fatty acids is the first essential step in managing cholesterol levels through diet.

Saturated Fats. Saturated fats are found predominantly in animal products, including meat and dairy products. They are strongly associated with higher cholesterol levels. Although certain fatty acids in saturated fats called stearic acids may have some benefits, there is no simple methods for defining foods that contain them, so, in general, saturated fats should be avoided. (The so-called tropical oils, palm, coconut, and cocoa butter, are also high in saturated fats. Evidence is lacking, however, about their effects on the heart. The countries with the highest palm-oil intake, Costa Rica and Malaysia, also have much lower heart disease rates and cholesterol levels than Western nations.)
Trans-fatty Acids. Trans-fatty acids are manufactured fats created during a process called hydrogenation, which is aimed at stabilizing polyunsaturated oils to prevent them from becoming rancid and to keep them solid at room temperature. Most are particularly dangerous for the heart and may pose a risk for certain cancers. And in fact, one 2001 study found that trans-fatty acids might actually increase the risk of developing diabetes type 2. Some experts believe that these partially hydrogenated fats are even worse than saturated fats because they both increase LDL and reduce HDL cholesterol levels and may have harmful effects on the linings of the arteries. One study of 80,000 nurses reported that women whose total fat consumption was 46% of total caloric intake had no greater risk in general for a heart attack than did those for whom fat represented 30% of calories consumed. Women whose diets were high in trans-fatty acids, however, had a 53% increased risk for heart attack compared to those who consumed the least of those fats. Hydrogenated fats are used in stick margarine and in many fast foods and baked goods, including most commercially produced white breads. (Liquid margarine is not hydrogenated and is recommended.) The FDA has now required that food labels include information on trans-fatty acids.

Beneficial Fats and Oils. It should be noted that some fat is essential for health, and fat is essential for healthy development in children. Public attention has mainly focused on the possible benefits or hazards of monounsaturated (MUFA) and polyunsaturated (PUFA) fats.

Polyunsaturated fats are found in safflower, sunflower, corn, and cottonseed oils and fish.
Monounsaturated fats are mostly present in olive, canola, and peanut oils and in most nuts.

Studies, however, do not all agree on their effects. Researchers are most interested in the smaller fatty-acid building blocks contained in both oils, which may have more specific effects on lipids. Three important fatty acids are the essential fatty acids omega-3, omega-6, and omega-9.

Omega-3 fatty acids: They are further categorized as alpha-linolenic acid and docosahexaenoic and eicosapentaneoic acids.
Docosahexaenoic (DHA) and Eicosapentaneoic (EPA) Acids. Fish oils, which contain docosahexaenoic (DHA) and eicosapentaenoic acids (EPA), have anti-inflammatory and anti-blood clotting effects and may be significantly beneficial to the heart. DHA is the most unsaturated of all fatty acids. These fatty acids may reduce triglyceride levels and have modest positive effects on HDL. In patients with high triglyceride levels, but not in others, omega 3 fatty acids may increase LDL. Overall cholesterol levels are not affected. DHA appears to have specific benefits on blood pressure. The International Society for the Study of Fatty Acids and Lipids, in fact, recommends fish oil supplements for heart protection. Omega-3 fatty acids in fish may reduce risks for other disorders, including stroke, rheumatoid arthritis, asthma, ulcerative colitis, and some types of cancers.
Alpha-linolenic Acid . Alpha-linolenic acid is a plant precursor of DHA, which means the body can convert it to DHA. Sources include canola oil, soybeans, flaxseed, and certain nuts and seeds (walnut, flax, chia and sometimes pumpkin seed). Studies have been positive about the effects on the heart of these oils or foods containing these oils.
Omega-6 polyunsaturated fatty acids. Sources are corn, safflower, soybean, and sunflower oil. PUFA oils containing omega-6 fatty acids constitute most of the oils consumed in the US. Some omega-6 fatty acids are important for health. There is some association with a higher risk for certain cancer and some chronic diseases with diets high in omega-6 fatty acids, however.
Omega-9 monounsaturated fatty acids: Sources are canola and olive oil. Extra virgin olive oil has been associated with lower blood pressure and a 2000 study reported that it may have specific benefits for people with diabetes type 2. Of concern is a small study reporting higher concentrations of LDL in subjects consuming an olive-oil rich diet compared to those on a sunflower or rapeseed oil rich diet.

Research suggests that our current Western diet contains an unhealthy high ratio (10 to 1) of omega-6 to omega-3 fatty acid. Omega-9 fatty acids may also contain chemicals that block harmful factors found in omega-6 fatty acids. Researchers are finding then that the most benefits may be found in mixture of all three fatty acids found in both poly- and monounsaturated oils, but in modest amounts that do not add too many calories.

Fat Substitutes. Fat substitutes added to commercial foods or used in baking deliver some of the desirable qualities of fat, but do not add as many calories. They include the following:

Some replacers, such as the cellulose gel Avicel, Carrageenan (made from seaweed), guar gum, and gum arabic, have been used for decades in many commercial foods.
Plant substances known as sterols have long been known to reduce cholesterol by impairing its absorption in the intestinal tract. Sterols are now being isolated as sterol derivatives or as stanols (which are saturated sterols) to produce margarines (Benecol, Take Control). Benecol is derived from pine bark and Take Control from soybeans. Studies on such margarines are reporting that either two servings a day as part of a low-fat diet can lower LDL and total cholesterol. It should be noted, however, that these margarines may be hydrogenated and include some trans-fatty acids. Of further concern is the possibility that stanol may block absorption of important fat-soluble nutrients, including vitamins A, E, and D and carotenoids (compounds, such best carotene, that convert to vitamin A). One study suggested that it had no effect on the vitamins but did impair absorption of beta carotene. In people already on a low-fat diet, the addition of this margarine may not produce much additional benefit.
Olestra (Olean) passes through the body without leaving behind any calories from fat. (It should be noted, however, that foods containing olestra still have calories from carbohydrates and proteins.) A 2000 study reported healthful changes in cholesterol levels in people who had been eating olestra for a year. Early reports of cramps and diarrhea after eating food containing olestra have not proven to be significant. Of greater concern is the fact that even small amounts of olestra deplete the body of certain vitamins and nutrients that are important for protection against serious diseases, including cancer. The FDA requires that the missing vitamins be added back to olestra products, but not other nutrients.
Under investigation are fat substitutes derived from beta-glucan, the soluble fiber found in oats and barley (eg, Nu-Trim). They may have health benefits beyond reducing calories and replacing hydrogenated or saturated fats.

People should try to limit even reduced-fat foods and fat substitutes in their diets. Although one might believe that eating reduced-fat or fat substitute products means consuming fewer calories, this is often not the case. Many commercial, lowered-fat products have extra calories from sugar and other carbohydrates. A study has found that people who consume foods that contain fat substitutes do not learn to dislike fatty foods, while people who learn to cook using foods naturally lacking or low in fat eventually lose their taste for high fat diets.

Some Examples of Healthy Foods

Foods	Phytochemicals and Carotenoids	Vitamins and other valuable food components	Benefits
Apples	Flavonoids		May have activity against certain cancers (lung). Also may help maintain healthy cholesterol.
Beans	Flavonoids	Folate, iron, potassium, and zinc.	Some experts believe beans are the perfect food.
Berries, all kinds of dark colored	Ellegic Acid	Vitamin C, minerals	May protect the aging brain. (In one study blueberries were most effective.)
Broccoli (also kale, Brussels sprouts, cauliflower)	Flavonoids, isothiocyanates, lutein, beta and alpha carotene	Vitamin C, folate, fiber, and selenium	Anticancer properties. Protective against heart disease and stroke.
Carrots and other bright yellow vegetables	Lutein, beta carotene and other provitamin A carotenoids.	Vitamin A (converted from carotenoids), Vitamin C	Protects eyes, lungs. (Cooking carrots may increases the potency of food nutrients.)
Eggs	lutein	Many B vitamins, vitamin A, vitamin D	Although egg yolks are high in cholesterol, very little of it has a negative effect on people with normal levels. And the health benefits of eggs are now known to be very high. (People with diabetes or those with high cholesterol should restrict eggs, however.)
Fish, oily (mackerel, salmon, sardines)		Vitamin B3, B12. Essential fatty acids, selenium	Heart and brain protective.
Garlic	Allium (organosulfurs)		Possibly protective against certain cancers, heart diseases, and infection. Heating garlic can reduce benefits. Allowing crushed fresh garlic to stand 10 minutes before heating, however, may preserve beneficial chemicals while cooking.
Ginger	Zingiberaceae		Cancer fighting properties.
Grains (whole)	Lignans (phytoestrogens)	Vitamin B, Selenium (important antioxidant mineral), fiber, folate	May help reduce the ability of cancer cells to invade health tissue.
Grapes, including purple grape juice, and red wine	Flavonoids, (resveratrol, quercetin and catechin)		Fight heart disease and cancer.
Nuts		Vitamin E, Vitamin B1, Essential fatty acids, folate	Protects the heart and may help prevent stroke.
Onions	Flavonoids, allium (organosulfurs)		May have activity against certain cancers (lung).
Oranges	Monoterpenes	Vitamin C, folate, potassium	Many health benefits. Increases HDL levels.
Potatoes (Sweet)		Vitamin C, vitamin E, vitamin A	Many health benefits.
Soy	Isoflavones (phytoestrogens), flavonoids, phytosterol, phytate, saponins		May have effects similar to estrogen, including maintaining bone and benefiting the heart. May also be protective against prostate cancer and possibly other cancers. More studies are needed. (Note: of some concern is one study reporting more mental decline in people who consume greater amounts of tofu.)
Spinach and other dark green leafy vegetables	Zeaxanthin, Beta carotene,	Vitamin C, folate, Vitamin A (converted from carotenoids)	Protects lungs and brain.
Tea (Green tea has reported best benefits)	Flavonoids		Cancer fighting properties, particularly in green tea. Black tea does not appear to have these particular benefits. Both black and green tea are heart protective and may protect against stroke.
Tomatoes	Lycopene, Flavonoids	Vitamin C, biotin, minerals	Studies link to reductions in prostate and other cancers. Infection fighters.

The story on cholesterol found in the diet is not entirely straightforward. Cholesterol is found only in animal tissues, with high amounts occurring in meat, dairy products, egg yolks, and shellfish. The American Heart Association recommends no more than 300 mg of cholesterol per day. One study estimated, however, that reducing dietary cholesterol intake by 100 mg/day would only produce a 1% decrease in cholesterol levels. Of note, however, are studies indicating that although dietary cholesterol itself does not appear to increase the risk for heart disease in most individuals, people with diabetes, especially type 2, may be an exception. Until more research is done, they should consider avoiding eating eggs or other high-cholesterol foods (such as shrimp) more often than once a week.

Vitamins and Supplements

Antioxidant Properties. Currently, the most important benefit claimed for vitamins A, C, E, and many of the carotenoids and phytochemicals is their role as antioxidants, which are scavengers of particles known as oxygen-free radicals (also sometimes called oxidants). These chemically active particles are by-products of many of the body's normal chemical processes. Their numbers are increased by environmental assaults, such as smoking, chemicals, toxins, and stress. In higher levels, oxidants can be very harmful:

They can damage cell membranes and interact with genetic material, possibly contributing to the development of a number of disorders including diabetes, cancer, heart disease, cataracts, and even the aging process itself.
Oxygen-free radicals can also enhance the dangerous properties of low-density lipoprotein (LDL) cholesterol, a major player in the development of atherosclerosis.

Antioxidant vitamins (A, C, and E), carotenoids, and many phytochemicals can neutralize free radicals and may reduce or even prevent some of their damage. Unfortunately, although it is clear that vitamins are required to prevent deficiency diseases, the possible benefits of higher-dose supplements are still unproven in most cases. To date, there is no strong evidence that antioxidant supplements offer any real protection. In some cases, high doses may be harmful.

Vitamin E. Vitamin E may prevent blood clots and the formation of fatty plaques and cell proliferation on the walls of the arteries. Long-term studies of people who take vitamin E supplements, however, are mixed:

Many have found little or no benefits. A very important major 2001 study, for example, found no protection against heart disease or stroke in high-risk patients. A 2000 one reported that patients who took natural forms of vitamin E at 400 IU for four to six years were not protected against cardiovascular disease. Still, the evidence is not altogether straight-forward. Vitamin E must be taken with oils or fats to have any effect, which might affect the outcome of some studies.
Of interest, however, is a very small 2000 study reporting that when people with type 2 diabetes took high doses (1,200 IU) of vitamin E they had less evidence of inflammation in blood vessels, an indicator for a higher risk of heart disease and stroke. Another reported that vitamin E had benefits on the central nervous actions governing the heart in people with type 2 diabetes.
Other studies have found similar benefits for people with type 1 diabetes after long term vitamin E supplementation, including beneficial effects on cholesterol levels and possible protection against kidney damage. Some experts, in fact, recommend life-long vitamin E supplements specifically for people with type 1 diabetes.

Different vitamin E compounds, such as gamma tocopherol or tocotrienol may have benefits that the standard synthetic supplement (dl alpha tocopherol) does not. Studies are fairly consistent in indicating that eating foods rich in natural vitamin E may be protective.

Vitamin C. Vitamin C appears to maintain blood vessel flexibility and to improve circulation in the arteries of smokers. Generally, such findings have occurred in the laboratory. In one English 2001 study, people whose diets were rich in foods that elevated levels of vitamin C in their blood were at lower risk for heart disease, overall poor health, and death. There is no evidence, however, that supplements of vitamin C offer any actual protection against heart disease, and a major 2001 study found no benefits for the heart in high-risk patients.

B Vitamins. Several important studies have demonstrated a link between deficiencies in the B vitamins folate, B6, and B12 and elevated blood levels of homocysteine, an amino acid believed to be a risk factor for atherosclerosis. Both B12 and folate reduce homocysteine levels, although it is not yet clear if this effect is actually protective against heart disease. (Homocysteine may simply be a marker, not a cause, of heart disease.) Major studies are under way and early results of small studies are promising. A 2001 study, for example, reported lower rates of heart disease in populations that had high levels of folate and B12 regardless of any other risk factors. Dosage of 0.8 mg/day of folic acid appears to be necessary for reducing homocysteine levels. Folate also improves blood flow through the arteries, which may be of equal or greater importance for the heart than its effect on homocysteine.

Another important B vitamin is niacin (Vitamin B3), which has special benefits for patients with unhealthy cholesterol levels. There has been some concern that high levels may actually have adverse effects on glucose control. [See also the Well-Connected report Cholesterol.]

Lipoic Acid. Lipoic acid, a coenzyme with antioxidant properties, is receiving some attention. In one very preliminary study, researchers found that treatment with lipoic acid may be more kidney protective than high doses of both vitamin C and E. More research is needed.

Minerals

Magnesium. Magnesium deficiency may have some role in insulin resistance and high blood pressure. One study reported that low magnesium levels as measured in blood tests were associated with a higher risk for type 2 diabetes in whites but not in African Americans. Dietary intake of magnesium, however, did not appear to play any role in increasing or reducing risk for either population group. It is more likely that diabetes may cause magnesium loss. No supplements are recommended at this time for patients with adequate levels of magnesium. For people taking diuretics for high blood pressure, extra potassium may be needed, but in other cases, including certain kidney problems, an overload of potassium may occur, so no regular supplements are recommended without consulting a physician.

Chromium. Some studies have reported an association between deficiencies in the mineral chromium and a higher risk for type 2 diabetes. Studies on fat rats that were given chromium reported improvement in insulin sensitivity and glucose metabolism. Studies on human type 2 patients, however, reported few benefits and some adverse side effects.

Zinc. Many type 2 diabetics are also deficient in zinc; more studies are needed to establish the benefits or risks of taking supplements. Zinc has some toxic side effects, and some studies have associated high zinc intake with prostate cancer.

Salt and Sodium

Salt can raise blood pressure, and people with diabetes should limit salt intake, particularly if they have hypertension, are overweight, or both. Overweight people who have a high sodium intake may be at increased risk for death from heart disease. High salt diets in people who are sensitive to its effects may harm the kidney and brain, even independently of high blood pressure. Restricting salt also enhances the benefits of nearly all standard antihypertensive drugs by reducing potassium loss, and may help protect against kidney disease in patients who are also taking calcium-blocker drugs.

Although it is not clear whether restricting sodium adds any benefits for most people whose diets are rich in fruits, vegetables, and low-fat dairy products and who are not salt-sensitive, it is always wise to aim for a maximum of 2,000 mg sodium intake. Simply eliminating table and cooking salt can be beneficial. Salt alternatives, such as Cardia, containing mixtures of potassium, sodium, and magnesium are now available but are costly. It should be noted, however, that about 75% of the salt in the typical American diet comes from processed or commercial foods, so the benefits of table-salt substitutes are likely to be very modest. Some sodium is essential to protect the heart, but most experts agree that the amount is significantly less than that found in the average American diet.

Caffeine and Alcohol

Alcohol. Studies in 1999 and 2000 have suggested that light to moderate alcohol intake (one or two glasses a day) may have specific benefits for people with type 2 diabetes. In one it was associated with a reduced risk for death from heart disease, and in the other it protected against type 2 diabetes itself. Red wine particularly appears to have health benefits. In one study, drinking red wine at meals even reduced blood glucose levels in some cases. (Alcohol itself had no effect on blood glucose or insulin.) In those taking insulin or sulfonylureas, however, alcohol may cause a hypoglycemic reaction, of which the drinker may not be aware. Pregnant women or those at risk for alcohol abuse should not drink alcohol.

Caffeinated Beverages.

Tea. Tea may have a very positive effect on the heart. Although it contains caffeine, it also is rich in flavonoids and other substances that offer protection against damaging forms of LDL. Green tea is often cited for its health benefits but black tea may also be beneficial. In one study, higher intake of black tea, particularly by women, was associated with a reduced risk for severe coronary artery disease. Tea also contains folic acid, which reduces homocysteine levels, a possible factor in coronary artery disease.
Coffee. Unfiltered coffee (Turkish coffee, Scandinavian boiled or French pressed coffee, and espresso) contains an alcohol called cafestol, which may raise cholesterol levels. Filtered coffee does not contain this residue. On the other hand, coffee, like red wine, contains phenol, which helps prevent oxidation of LDL cholesterol. One study reported no association between coffee consumption and fatal or nonfatal heart disease after 10 years. In fact, the highest rates of fatal heart disease were in non-coffee drinkers, and women who increased their coffee intake reduced their mortality rates. Regular intake of coffee does have a harmful effect on blood pressure in people with existing hypertension. (Caffeine causes a temporary increase in blood pressure in everyone, which is thought to be harmless in people with normal blood pressure.)

Of note, a 1999 study reported an effect of caffeine on the brain that has implications for diabetes: it reduces blood flow in the brain even in the presence of sufficient glucose. People with diabetes who drink even two or three cups of coffee may actually believe they are hypoglycemic when their blood glucose levels are normal. One study suggested that this effect may actually help increase awareness of hypoglycemia in some people who have difficulty recognizing its symptoms.

WHAT ARE THE WEIGHT CONTROL AND DIETARY APPROACHES FOR TYPE 2 DIABETES?

Weight control is an especially important part of the management of type 2 diabetes. A 1999 analysis of 2,800 individuals who had lost at least 30 pounds and maintained the weight loss for more than year reported the following: about 55% had been involved in a formal weight loss program, 20% succeeded with liquid diets, only 4.3% used medications, and 1.3% had surgery. And, importantly, 80% reported that they exercised more often and more vigorously than with previous attempts. [For more detailed information see the Well-Connected report, Obesity.]

General Approach to Weight Loss and Maintenance

Life long changes in eating habits, physical activity, and attitudes about food and weight are essential to weight management. The following offer some general suggestions for dieters:

Start with realistic goals. Diet failure is extremely common and the odds of significant weight loss are poor, particularly in people with the highest weights. People embarking on a weight loss program should keep in mind that only a 5% to 10% reduction in weight, even in people who are obese, can improve health significantly. Certainly, the current unwholesome and distorted image of a super-thin female shape is a cultural idea that almost no one can or should achieve. (Anorexia, obesity's alter ego, is less common but is the other side of this dysfunctional aspect of our culture.) Obesity, however, still poses a threat to life, health, and well being, and the struggle against it is worthwhile. And obesity in children is never acceptable, unless there is a proven medical reason.
The simplest (but still difficult) approach to weight loss is reducing calories and exercising at least 150 minutes a week. One study suggested that only about 20% of people who try to lose weight use these effective methods. (It should be noted that many physicians have limited time as well as training in nutrition and weight management and some may be tempted to prescribe diet pills, particularly when urged by the patient, even though a diet and exercise have not been tried.)
Hunger pangs should not be taken as cues to eat. A stomach that has been stretched by large meals will continue to signal hunger for large amounts of food until its size reduces over time with smaller meals.
Once a person has lost weight, maintenance is required. To maintain a healthy weight in our culture, everyone must make daily, even hourly, decisions about what is consumed and what is expended through activity. Such thinking, in many cases, can become automatic and not painful.
Even repeated weight loss failure is no reason to give up. Most studies indicate that yo-yo dieting or weight cycling has no adverse psychological or physical effects. (Of some concern was a 2000 study reporting lower HDL levels, the so-called good cholesterol, in women whose weight cycled from frequent dieting. No other heart risks were evident, however.) Repeated dieting also does not impair the body's ability to burn calories efficiently.
Weight loss, in any case, should not be the only or even the primary goal for people concerned about their health. The success of weight reduction efforts should be evaluated according to improvements in chronic disease risk factors or symptoms and by the adoption of healthy lifestyle habits, not by just the number of pounds lost.

Calorie Restriction. Calorie restriction has been the cornerstone of obesity treatment. The standard dietary recommendations for losing weight are the following:

As a rough rule of thumb, one pound of fat equals about 3,500 calories, so one could lose a pound a week by reducing daily caloric intake by about 500 calories a day. Naturally, the more severe the daily calorie restriction, the faster the weight loss. Very-low calorie diets have also been associated with better success, but extreme diets can have some serious health consequences. [ See Box Warning on Extreme Diets.]
To determine the daily calories requirements for specific individuals, multiply the number of pounds of ideal weight by 12 to 15 calories. The number of calories per pound depends on gender, age, and activity levels. For instance a 50-year old woman who wants to maintain a weight of 135 pounds and is mildly active might require only 12 calories per pound (1,620 calories a day). A 25-year old female athlete who wants to maintain the same weight might require 25 calories per pound 2,025 (calories a day).
Fat intake should be no more than 30% of total calories. Most fats should be in the form of monounsaturated fats (such as olive oil) and saturated fats (found in animal products) should be avoided.

Warning on Extreme Diets

Extreme diets of less than 1,100 calories carry health risks and are often followed by bingeing or overeating and a return to the obese state. Such diets often have insufficient vitamins and minerals, which must then be taken as supplements. Most of the initial weight loss is in fluids. Later, fat is lost, but so is muscle, which can account for more than 30% of the weight loss. No one should be on severe diets longer than 16 weeks or fast for more than two or three days. Severe dieting has unpleasant side effects, including fatigue, intolerance to cold, hair loss, gallstone formation, and menstrual irregularities. There have been rare reports of death from heart arrhythmias when liquid formulas did not have sufficient nutrients. Of note, those whose diets include a high intake of fluids and much reduced protein and sodium are at risk for hyponatremia, which can cause fatigue, confusion, dizziness, and in extreme cases, coma.

Low-Fat High-Complex Carbohydrates. Some studies suggest that replacing foods high in fats and sugars with low-fat complex carbohydrates (fruits, vegetables, and whole grains) may be more effective for weight control than calorie counting. In one study, people with type 2 diabetes who were unable to exercise achieved significant reductions in blood glucose levels and body weight with a strict vegetarian (no dairy or meat) low-fat diet. Consuming insoluble fiber (found in wheat bran, whole grains, seeds, and fruit and vegetables) may be an important component for weight loss from this diet. (Soluble fiber does not appear to have much effect on weight.) Some dietary fat is essential; such fats should be derived from monounsaturated oils and fish.

Still, the high-carbohydrate low-fat diet has come under scrutiny. Some diabetics may have problems with cholesterol and triglyceride levels when carbohydrates constitute over 50% of the diet. If triglycerides are high, carbohydrates should be reduced to 45%. It should be noted that replacing fatty foods, such as cakes, cookies, and chips, with their commercial "low-fat" counterparts does not constitute a low-fat diet. These foods generally contain more sugar and hence calories, not to mention other ingredients which have virtually no nutritional value. In fact, a 2002 study suggested that increased sugar consumption may reduce levels of HDL cholesterol, the so-called good cholesterol.

Of some reassurance, a 2000 study compared two groups of type 2 subjects. One group increased carbohydrate intake by 10% with breakfast cereal and the other consumed the same calories with monounsaturated fat oils. At the end of six months, the cereal eating group actually had a better insulin profile than the MUFA group. There were no significant differences in cholesterol levels, body fat, or glycolated hemoglobin. [ See also The Ornish Program and Severely Fat-Restricted Diets under What Are the General Guidelines for Heart-Healthy Diets?]

High-Protein Low-Carbohydrate Diet. High-protein diets can be very effective in producing short-term weight loss, but their long-term effects on health are in question. They may be particularly harmful for people with diabetes. Such diets are currently popular and include the Zone, Dr. Atkins, Protein Power, Sugar Busters, and Dr. Stillman.

High-Fat Low-Carbohydrate Diet. Some studies suggest that replacing carbohydrate calories with monounsaturated fats (such as olive oil) does not harm cholesterol levels and may improve glucose control. (Calories must still be restricted, however.)

Structured Snacks

Low-calorie snack packages (Lean on Me, Level Best) are being developed for people with type 2 diabetes that contain supplements (such as psyllium, barley, fructose, green-tea extract, chromium picolinate and 5-http) associated with claims for improving factors that affect the heart and diabetes. Although promising, these packages have not been clinically studied, and patients should be warned that their long-term risks and benefits are not known.

WHAT ARE THE GENERAL GUIDELINES FOR HEART-HEALTHY DIETS?

Any diet should be healthy for the heart. Currently, there is much controversy over the best balance of carbohydrates, fats, and protein. The three major cholesterol reduction diets are the following:

The Step 1 and Step 2 diets recommended by the American Heart Association.
The Mediterranean Diet.
Very low-fat diets, such as the Ornish Program.

[For more detail see Well-Connected Report #43 Heart-Healthy Diet.]

American Heart Association Diet Recommendations

AHA Diet is in two stages, depending on heart disease risk.

Recommendations for People with Normal Risk.

Choose fiber-rich whole grains, legumes, and fresh fruits and vegetables.
When fats are recommended, avoid saturated foods and choose unsaturated fatty acids from vegetables, fish, legumes, and nuts. Dairy products should be low- or no-fat.
Limit salt.
Limit alcohol (no more than 1 drink per day for women and 2 drinks per day for men).
Maintain healthy body weight.
Maintain a healthy level of physical fitness.

Recommendations for People with Health Problems. Individual diet plans should be developed that take into consideration the individuals specific problems, including lipids, blood pressure, and the presence of diabetes. So, for patients with elevated LDL cholesterol and a history of heart disease, the following are recommended:

Follow general guidelines for healthy diet.
No more than 7% of total calories as saturated fat. Patients with very low intake of total fat (less than 15% of total calories) should be monitored for possible increases in triglyceride and reductions in HDL cholesterol.
No more than 200 mg of cholesterol per day. Lower levels may provide additional benefits.
One study suggested that American Heart Association dietary recommendation are as effective for weight loss and controlling blood glucose, blood pressure, and cholesterol in people with type 2 diabetes as exchange lists are. No studies have been conducted on any specific benefits or risks using the most recent AHA guidelines.

Mediterranean Diet

The Mediterranean diet is rich in heart-healthy fiber and nutrients, including omega-3 fatty acids and antioxidants. The diet recommends the following:

A relatively high fat intake (about 35% to 45% of daily calories, mostly in monounsaturated and polyunsaturated fats.
Daily glass or two of wine.
The same protein intake as the AHA, although fish is the primary source. Recommends red meat only a few times a month. Avoids high-fat dairy products.
Lower carbohydrate intake than AHA. Emphasizes not only fresh fruits and vegetables, but also higher amounts of nuts, legumes, beans, and whole grains.
Food seasoned with garlic, onions, and herbs.

Positive Arguments. Evidence is increasingly strong on the heart-protective properties of this diet and studies are reporting that it is more beneficial than the AHA approach in lowering total and LDL cholesterol and triglyceride levels. It appears to have little, either positive or negative, effect on, HDL levels. Studies report the following:

One suggested a significantly lower risk for a second heart attack after an average of four years compared to a conservative Western diet.
The Mediterranean diet is known for its use of olive oil, which may have some effects on improving insulin and blood glucose levels and reducing blood pressure.

Negative Arguments. Weight gain from the high intake of fats can be a problem with this diet, however, in anyone who has to watch calories. Other concerns with the Mediterranean diet are reduced iron levels and possible calcium loss resulting from consumption of fewer dairy products.

The Ornish Program and Severely Fat-Restricted Diets

The Ornish program limits saturated fats as much as possible, reduces total fat to 10%, and increases carbohydrates to 75% of calories. It is a very effective but demanding regimen:

It excludes all oils and animal products except nonfat yogurt, nonfat milk, and egg whites.
Foods stressed are whole grains, legumes, and fresh fruits and vegetables.
People in the program exercise 90 minutes at least three times a week.
Stress reduction techniques are employed.
People do not smoke or drink more than two ounces of alcohol per day.

People on low fat diets should consume a wide variety of foods and take a multivitamin if appropriate.

Positive Arguments. Low-fat diets that are high in fiber, whole grains, legumes, and fresh produce offer health advantages in addition to their effects on cholesterol.

One study reported that the diet reduced LDL levels to recommended levels without the addition of a cholesterol-lowering drug. The program directors have reported a 91% reduction in angina after one year and a 72% reduction after four years in spite of significant HDL cholesterol reduction.
In one study, people with type 2 diabetes who were unable to exercise achieved significant reductions in blood glucose levels and body weight with a strict vegetarian (no dairy or meat) low-fat diet.
It protects against high blood pressure.
It may possibly protect against certain cancers.

Negative Arguments. The American Heart Association argues that the Ornish program is so difficult to maintain that it will not benefit many people. The comparison study showing the advantage of the Ornish over the Step 2 diet, in fact, was very small because few participants could sustain the efforts needed to fulfill the requirements of the Ornish program for five years.

Some experts argue that it is not clear whether fat-restriction or the other elements in the program, exercise and stress reduction, are mainly responsible for its benefits.

High-carbohydrate and low-fat diets can reduce HDL levels.
Type 2 diabetics who tend to be overweight and insulin-resistant overproduce glucose after carbohydrate intake, which in turn requires more insulin to process it. This leads to appetite stimulation and production of fat.
Very low-fat diets may also increase the risk for stroke from hemorrhage in the brain.
Very low fat diets may reduce calcium absorption, which may be particularly harmful in women at risk for osteoporosis.

Many people who reduce their fat intake do not consume enough of the basic nutrients, including vitamins A and E, folic acid, calcium, iron, and zinc. People on low-fat diets should consume a wide variety of foods and take a multivitamin if appropriate.

The DASH Diet

A diet known as Dietary Approaches to Stop Hypertension (DASH) is now recommended as an important step in managing blood pressure. This diet is not only rich in important nutrients and fiber but also includes foods that contain two and half times the amounts of electrolytes, potassium, calcium, and magnesium, as are found in the average American diet. It makes the following recommendations:

Avoid saturated fat (although include calcium-rich dairy products that are no- or low-fat).
When choosing fats, select monounsaturated oils, such as olive or canola oils. (One study reported a reduced need for anti-hypertension medication in people with a high intake of virgin olive oil, but no sunflower oil, a polyunsaturated fat.)
Choose whole grains over white flour or pasta products.
Choose fresh fruits and vegetables every day. Important foods include most fruits (especially potassium-rich fruits including bananas, oranges, prunes, and cantaloupes) and vegetables (especially carrots, spinach, celery, alfalfa, mushrooms, lima beans, potatoes, avocados, broccoli). Note: Grapefruit boosts the effects of calcium channel blocking drugs, which are often used for hypertension. (Regular oranges do not appear to pose any hazard, but one study suggested that Seville oranges, also called bitter oranges, may be similar to grapefruit in their effect.)
Include nuts, seeds, or legumes (dried beans or peas) daily.
Choose modest amounts of protein (preferably fish, poultry, or soy products). Oily fish may be particularly beneficial.

In one study, after eight weeks on the diet, subjects from a broad range of backgrounds experienced a significant reduction in blood pressure. A 2000 study reported that a combination of the DASH diet and salt restriction is very effective in reducing blood pressure. (Each approach has positive benefits, but the combination is best.) Some individuals should take particular measures to restrict salt. [For more information see the Well-Connected report on High Blood Pressure.] [For detailed information see the Well-Connected report, Heart-Healthy Diet .]

WHAT ARE THE DIABETIC EXCHANGE LISTS?

General Guidelines for Exchange Lists

The objective of the exchange lists is to maintain the proper balance of carbohydrates, proteins, and fats throughout the day. The exchange lists can be obtained by calling or writing the American Diabetes Association. [ See Where Else Can Help Be Obtained for Diabetes Diet?]

In developing a menu, patients must first establish with a doctor or dietitian their individual dietary requirements, particularly the optimal number of daily calories and the proportion of carbohydrates, fats, and protein. The exchange lists should then be used to set up menus for each day that fulfill these requirements.

The following are some general rules:

The diabetic exchanges are six different lists of foods grouped according to similar calorie, carbohydrate, protein, and fat content; these are starch/bread, meat, vegetables, fruit, milk, and fat. A person is allowed a certain number of exchange choices from each food list per day.
The amount and type of these exchanges are based on a number of factors, including the daily exercise program, timing of insulin injections, and whether or not an individual needs to lose weight or reduce cholesterol or blood pressure levels.
Foods can be substituted for each other within an exchange list but not between lists even if they have the same calorie count.
In all lists (except in the fruit list) choices can be doubled or tripled to supply a serving of certain foods. (For example three starch choices equal 1 1/2 cups of hot cereal or three meat choices equal a 3-ounce hamburger.)
On the exchange lists, some foods are "free." These contain less than 20 calories per serving and can be eaten in any amount spread throughout the day unless a serving size is specified.

Exchange List Categories

The following are the categories given on the exchange lists:

Starches and Bread. Each exchange under starches and bread contains about 15 grams of carbohydrates, 3 grams of protein, and a trace of fat for a total of 80 calories. A general rule is that a half cup of cooked cereal, grain, or pasta equals one exchange and one ounce of a bread product is one serving.

Meat and Cheese. The exchange groups for meat and cheese are categorized by lean meat and low fat substitutes, medium-fat meat and substitutes, and high-fat. High fat exchanges should be used at a maximum of 3 times a week. Fat should be removed before cooking. Exchange sizes on the meat list are generally one ounce and based on cooked meats (three oz of cooked meat equals 4 oz of raw meat).

Vegetables. Exchanges for vegetables are 1/2 cup cooked, 1 cup raw, and 1/2 cup juice. Each group contains 5 grams of carbohydrates, 2 grams of protein, and between 2 to 3 grams of fiber. Vegetables can be fresh or frozen; canned vegetables are less desirable because they are often high in sodium. They should be steamed or microwaved without added fat.

Fruits and Sugar. Sugars are now included within the total carbohydrate count in the exchange lists. Sugars still should not be more than 10% of daily carbohydrates. Each exchange contains about 15 grams of carbohydrates for a total of 60 calories.

Milk and Substitutes. The milk and substitutes list is categorized by fat content similar to the meat list. A milk exchange is usually one cup or 8 oz. For those who are on weight-loss or low-cholesterol diets, the skim and very low-fat milk lists should be followed, and the whole milk group avoided. Others should use the whole milk list very sparingly. All people with diabetes should avoid artificially sweetened milks.

Fats. A fat exchange is usually 1 teaspoon but it may vary. People, of course, should avoid saturated and trans-fatty acids and choose polyunsaturated or monounsaturated fats instead.

Number of Exchanges per Day for Various Calories Levels
Calories	1200	1500	1800	2000	2200
Starch/Bread	5	8	10	11	13
Meat	4	5	7	8	8
Vegetable	2	3	3	4	4
Fruit	3	3	3	3	3
Milk	2	2	2	2	2
Fat	3	3	3	4	5

WHAT IS CARBOHYDRATE COUNTING AND BLOOD GLUCOSE CONTROL?

The Carbohydrate Counting System

The system called carbohydrate counting is based on two premises:

All carbohydrates (either from sugar or starch) will raise blood sugar to a similar degree. In general, one gram of carbohydrates raises blood sugar by 3 points in people who weigh 200 pounds, 4 points for weights of 150 pounds, and 5 points for 100 pounds.
Carbohydrates have the greatest impact on blood sugar; fats and protein play only minor roles.

In other words, the amount of carbohydrates eaten (rather than fats or proteins) will determine how high blood sugar levels will rise. There are two options for counting carbohydrates: advanced and simple. Both rely on the collaboration with a physician, dietitian, or both. Once the patient learns how to count carbohydrates and adjust insulin doses to their meals, many find it more flexible, more accurate in predicting blood sugar increases, and easier to plan meals than other systems.

Creating the Plan

The basic goal is to balance insulin with the amount of carbohydrates eaten in order to control blood glucose levels after a meal. The steps to the plan are as follows:

The patient must first carefully record a number of factors that are used to determine the specific requirements for a meal plan based on carbohydrate grams:

Multiple blood glucose readings (taken several times a day).
The time of meals.
Amount in grams of all the carbohydrates eaten.
Time, type, and duration of exercise.
The time, type, and dose of insulin or oral medications.
Other relevant factors, such as menstruation, illness, and stress.

The patient works with the dietitian for two or three 45 to 90 minute sessions to plan how many grams of carbohydrates are needed. There are three carbohydrate groups:

Bread/starch.
Fruit.
Milk.

One serving from each group should contain between 12 and 15 carbohydrate grams. (Patients can find the amount of carbohydrates in foods from labels on commercial foods and from a number of books and web sites.)

The dietitian creates a meal plan that accommodates the patient's weight and needs, as determined by the patient's record, and makes a special calculation called the carbohydrate to insulin ratio . This ratio determines the number of carbohydrate grams that a patient needs to cover the daily pre-meal insulin needs.

Eventually, patients can learn to precisely adjust their insulin doses to their meals.

It should be noted that patients who choose this approach must still be aware of protein and fat content in foods. They may add excessive calories and saturated fats. Patients must still follow basic healthy dietary principles.

WHAT IS THE GLYCEMIC INDEX?

Description of the Glycemic Index

Not all carbohydrates are equal in how quickly or slowly they raise blood glucose. Choosing carbohydrates that have a slower effect on blood glucose may help control the surge in blood glucose that occurs after meals (called postprandial hyperglycemia). A rating system called the glycemic index helps patients predict how quickly specific foods affect blood sugar. [ See Table The Glycemic Index of Some Foods, below.]

The following are some tips to remember in choosing this approach:

The glycemic index uses a scale of numbers for foods with carbohydrates that have the slowest to highest effects on blood sugar. There are currently two indexes in use. One uses a scale of 1 to 100 with 100 representing a glucose tablet, which has the most rapid effect on blood sugar. This report uses the glucose index. [ See table, below.] The other common index uses a scale with 100 representing white bread (so some foods will be above 100.)
The numbers attributed to each carbohydrate-rich food are not additive. In other words, adding All Bran cereal (index of 49) to a banana (index of 61) does not equal 110.
Adding certain fats to a food, for example butter to potato, can slow down the potato's impact on blood sugar. One study reported that when patients ate fatty foods first, their blood glucose levels were significantly lower an hour after the meal than when carbohydrates were eaten first. (Another study indicated, however, that monounsaturated fats may not have the same effects as other fats.)
Adding foods with organic acids (pickles, yogurt) to meals may lower the impact of foods with high glycemic scores on blood sugar. (It should be noted that yogurt alone, however, has the same high glycemic index as regular milk.)

In addition to helping control blood glucose, diets rich in foods that have a low glycemic index appear to have added health benefits:

Some studies suggest they improve cholesterol and triglyceride levels and may even reduce the risk for kidney disease.
A 1999 study reported that boys who consumed meals with a high-glycemic index tended to eat more snacks than those who consumed food with a low-glycemic index, suggesting a greater risk for weight gain.

No one should use the glycemic index as a complete dietary guide, however, since it does not provide nutritional guidelines for all foods. It is simply an indication of how the metabolism will respond to carbohydrates eaten. Some experts believe it is too complicated to be practical and that simply tracking carbohydrates, eating healthily, and maintaining a healthy weight is sufficient.

The Glycemic Index of Some Foods Based on 100 = a Glucose Tablet.
BREADS
pumpernickel	49
rye	64
white	69
whole wheat	72
GRAINS
barley	22
sweet corn	58
brown rice	66
white rice	72
BEANS
soy	14
red lentils	27
kidney	33
chickpeas	36
baked	43
DAIRY PRODUCTS
milk	34
ice cream	38
CEREALS
oatmeal	53
All Bran	54
Swiss Muesli	60
Shredded Wheat	70
Corn Flakes	83
Puffed Rice	90
PASTA
spaghetti-protein enriched	28
spaghetti	38
macaroni	46
FRUIT
strawberries	32
apple	38
orange	43
orange juice	49
banana	61
POTATOES
sweet	50
yams	54
new	58
mashed	72
instant mashed	86
white	87
SNACKS
potato chips	56
oatmeal cookies	57
corn chips	72
SUGARS
fructose	22
refined sugar	64
honey	91
Note. These numbers are general values, but may vary widely depending on other factors, including if and how they are cooked and foods they are combined with.

WHAT NONDIETARY BEHAVIORS HELP CONTROL DIABETES?

Exercise

Diabetes, particularly type 2, is reaching epidemic proportions throughout the world as more and more cultures adopt Western dietary habits. Aerobic exercise is proving to have significant and particular benefits for people with both type 1 and type 2 diabetes.

Benefits of Exercise for People with Diabetes

People with diabetes are at particular risk for heart disease, so the heart protective effects of exercise are very important for this patient population. Moderate exercise, in fact, protects the heart in people with type 2 diabetes, even if they have no other risk factors for heart disease than diabetes itself.
Aerobic exercise is proving to have significant and particular benefits for people with type 1 and type 2 diabetes. It increases sensitivity to insulin, lowers blood pressure, improves cholesterol levels, and decreases body fat.
One study reported that yoga helped patients with type 2 diabetes reduce their need for oral medications.
Studies suggest that regular, moderate, aerobic exercise lowers the risk for developing diabetes type 2 in the first place in overweight people, even if they don't lose weight.
There is some indication that aerobic exercise before and during pregnancy can lower glucose levels and may be protective for women at risk for or who have gestational diabetes. (Any pregnant women should check with her physician before embarking on a vigorous exercise regimen.)

Some Precautions for People with Diabetes Who Exercise

All people with diabetes should check with their physician before starting a program. The following are precautions for all people with diabetes:

Because people with diabetes are at higher than average risk for heart disease, they should always check with their physicians before undertaking vigorous exercise. For best and fastest results, frequent high-intensity (not high-impact) exercises are best for people who are cleared by their physicians. For people who have been sedentary or have other medical problems, lower-intensity exercises are recommended using regimens designed with physicians.
Strenuous strength training or high-impact exercise is not recommended for uncontrolled diabetes. Resistance or high-impact exercises can strain weakened blood vessels in the eyes of patients with retinopathy. High-impact exercise may also injure blood vessels in the feet.

Patients who are taking medications that lower blood glucose, particularly insulin, should take special precautions before embarking on a workout program.

Glucose levels swing dramatically during exercise, people with diabetes should monitor their levels carefully before, during, and after workouts.
Patients should probably avoid exercise if glucose levels are above 300 mg/dl or under 100 mg/dl.
To avoid hypoglycemia, diabetics should inject insulin in sites away from the muscles they use the most during exercise.
Before exercising, they should also avoid alcohol and if possible certain drugs, including beta-blockers, which increase the risk of hypoglycemia.
Insulin-dependent athletes may need to decrease insulin doses or take in more carbohydrates, especially in the form of pre-exercise snacks (skim milk is particularly helpful). They should also drink plenty of fluids.

WHERE ELSE CAN INFORMATION BE OBTAINED ON DIABETES DIETS?

American Diabetes Association, ATTN: Customer Service, 1701 Beauregard Street, Alexandria, VA 22311
Call (800-232-3472) or (800-DIABETES) or on the Internet (http://www.diabetes.org/) and their latest recommendations for diabetes diet (http://care.diabetesjournals.org/cgi/content/full/25/1/202) This is the primary source for information on diabetes.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Building 31, Room 9A04, 31 Center Drive, MSC 2560, Bethesda, MD 20892-2560. Call (301) 654-3327 or on the Internet (http://www.niddk.nih.gov/)
A source of information for research advances and clinical trials currently underway. For those who have relatives with diabetes and may be at risk and are interested in participating in a trial on prevention, call (800-Halt-DM-1).

Juvenile Diabetes Foundation, International, 120 Wall Street, 19th floor, New York, NY 10005. Call (212-785-9500) or call (800-JDF-CURE)
or on the Internet (http://www.jdfcure.com/)

National Eye Health Education Program, National Eye Institute, 2020 Vision Place, Bethesda MD 20892. Call 301-496-5248) or (800-869-2020)
or on the Internet (http://www.nei.nih.gov/ )

American Dietetic Association, 216 West Jackson Boulevard, Suite 800, Chicago IL 60606-6995. Call (312-899-0040) or on the Internet (http://www.eatright.org/)
This organization provides names of local dietitians and programs through their Dietitian Referral Hotline: Call (800-366-1655) from 9AM to 4PM.
For customized answers to food and nutrition questions:
Call (900-225-5267) charge is $1.95 for the first minute and $.95 for each additional minute.

US Food and Drug Administration, 5600 Fishers Lane, Rockville, MD 20857-0001. Call (888-INFO-FDA) or on the Internet (http://www.fda.gov/)

Well-reviewed software for managing diet and glucose control
(http://www.healthviewdiabetes.com/)

On the Internet:

Informational site for professionals
(http://www.diabetesincontrol.com/)

Children with Diabetes dietary page
(http://www.childrenwithdiabetes.com/d_08_000.htm)

Iowa State University Extension, Food and Nutrition Publications (http://www.extension.iastate.edu/pubs/fo1.htm)

International Food Information Council
(http://ificinfo.health.org/)

Nutrition Analysis Tool
(http://spectre.ag.uiuc.edu/~food-lab/nat/)

Diabetic Gourmet Magazine
(http://gourmetconnection.com/diabetic/)

For more information on soy, call the Soy Hotline (1-800-TALKSOY)
or visit the Soy Website (http://www.soyfoods.com)

For a Glycemic index of a number of foods, including commercial cereals
(http://www.mendosa.com/gilists.htm)

Good lists of fiber-rich foods
(http://www.slrhc.org/healthinfo/dietaryfiber/)

ABOUT WELL-CONNECTED

Well-Connected reports are written and updated by experienced medical writers and reviewed and edited by the in-house editors and a board of physicians, who have faculty positions at Harvard Medical School and Massachusetts General Hospital. Neither Harvard Medical School or Massachusetts General Hospital, as Institutions, review or endorse this content. The reports are distinguished from other information sources available to patients and health care consumers by their quality, detail of information, and currency. These reports are not intended as a substitute for medical professional help or advice but are to be used only as an aid in understanding current medical knowledge. A physician should always be consulted for any health problem or medical condition. The reports may not be copied without the express permission of the publisher.

Board of Editors

Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

Stephen A. Cannistra, MD, Oncology, Associate Professor of Medicine, Harvard Medical School; Director, Gynecologic Medical Oncology, Beth Israel Deaconess Medical Center

Masha J. Etkin, MD, PhD, Gynecology, Harvard Medical School; Physician, Massachusetts General Hospital

John E. Godine, MD, PhD, Metabolism, Harvard Medical School; Associate Physician, Massachusetts General Hospital

Edwin Huang, MD, Gynecology, Harvard Medical School; Physician, Massachusetts General Hospital

Daniel Heller, MD, Pediatrics, Harvard Medical School; Associate Pediatrician, Massachusetts General Hospital; Active Staff, Children's Hospital

Paul C. Shellito, MD, Surgery, Harvard Medical School; Associate Visiting Surgeon, Massachusetts General Hospital

Theodore A. Stern, MD, Psychiatry, Harvard Medical School; Psychiatrist and Chief, Psychiatric Consultation Service, Massachusetts General Hospital

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Cynthia Chevins, Publisher

Bruce Carlson, Business Development Manager

Carol Peckham, Editorial Director

Lea Kling, Update Editor

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