Section Four: Diabetes
Diabetes mellitus is a condition in which sugar builds up in the bloodstream. Normally, insulin escorts it into the cells. In diabetes, however, insulin works poorly or not at all, allowing sugar to build up and, eventually, to filter through the kidneys into the urine. People with diabetes are at greatly increased risk for circulatory problems in the heart, eyes, kidneys, and extremities.
Both insulin-dependent and non-insulin dependent forms of diabetes have strong links to diet for both their causes and treatment.
When diabetes occurs in children, it is because the insulin-producing cells in the pancreas are no longer functioning. A commonly cited causal hypothesis combines genetic vulnerabilities, cow’s milk proteins, and viral exposures:
Under certain conditions, cow’s milk proteins pass through the gut into the bloodstream, eliciting the production of antibodies. These antibodies end up attacking not only the milk proteins but also pancreatic beta-cell proteins that happen to be structurally similar to those in cow’s milk. Viral infections cause these beta-cell proteins to be exposed to the antibodies. During viral infections over the next several years, intermittent antibody attacks gradually destroy the beta cells. In late childhood or early adulthood, insulin levels are so low that diabetes becomes manifest.
While this hypothesis remains controversial, the evidence supporting it is strong. In 1992, the New England Journal of Medicine reported that, of 142 children recently diagnosed with diabetes, all had high levels of antibodies to a particular cow’s milk protein.1 A 1996 research study published in The Lancet, again suggested that milk may contribute to diabetes in children.2
In 1994, the American Academy of Pediatrics convened a panel to examine the issue, concluding that exposure to cow’s milk protein may indeed be an important factor in the development of diabetes. Based on the more than 90 studies that had addressed the issue, the Academy reported that avoiding cow’s milk exposure may delay or prevent the disease in susceptible individuals.3
Between 20 percent and 30 percent of children have genes that permit the development of diabetes, although only about 3 in 1,000 develop the disease. These children will require insulin injections regardless of the diet they follow, although proper nutrition can help them minimize their doses and reduce complications. Breast-feeding and strict avoidance of cow’s milk products in infancy may reduce the risk of diabetes. Breast-feeding should be strongly encouraged, and practical problems (e.g., work schedules) that often interfere with it should be addressed early on. When breast-feeding is impossible, soymilk formulas are preferred over cow’s milk products and are available in all hospital nurseries and grocery stores. There is little evidence that soy products contribute to diabetes risk, although some researchers are holding that possibility open based on limited data from animal experiments. Patients should be cautioned to select only infant soy formulas, not adult soymilk products.
In adult-onset (or non-insulin-dependent) diabetes, insulin is present in the blood, but is not working adequately. This form of the disease can improve or even disappear with the right kind of diet and exercise.
Diabetes often accompanies obesity and remits with weight loss. It is also associated with high-fat diets. Although there is a strong genetic component to diabetes, diet and exercise often determine whether the genetic endowment will be expressed or not.
Older diets for treating diabetes were based on the theory that starches should be greatly restricted. Unfortunately, eliminating starches meant removing healthful grains, beans, and vegetables, and leaving the patient with foods that were high in fat or protein. Fat in the diet impairs insulin’s function, and excess protein accelerates kidney damage and causes other problems.
The next generation of “diabetic diets” used a set of exchange lists that rigidly prescribed certain amounts of milk, fruit, vegetables, starch, meat, and fat to be eaten each day in order to keep the diet fairly constant. This made it easier to gauge the amount of medicine needed to regulate blood sugar. Such diets were an improvement over older diets, but did not help most patients get off their medicines or escape serious complications. In spite of their limitations, these diets are still in use at many medical centers.
Carbohydrate counting is an extension of the use of exchange lists in which individuals keep track of the amount of carbohydrate they consume and adjust their insulin dosages accordingly.
A new and much more effective approach began with research studies in the early 1980s that eliminated exchange lists and focused on selecting foods to make postprandial sugar absorption more gradual and improve insulin function. There are three principles to such diets:
- Low-fat foods help insulin work better. Fat promotes insulin resistance. If there is very much fat in the blood or if a patient has excess body fat, insulin’s action deteriorates markedly, in what has been likened to “insulin’s hand slipping on the cells’ greasy doorknob.” Sugar builds up in the blood, and insulin cannot do much about it. Reducing dietary fat is a very powerful step, and one that the exchange lists do not take full advantage of, because they traditionally call for a relatively liberal fat intake, including butter, meat, oils, and other fatty foods.
- Complex carbohydrates release their sugars gradually. The starchy part of beans, vegetables, and grains is complex carbohydrate, natural sugars that are chemically linked together in a chain. During digestion, these sugars gradually come apart and pass into the blood a bit at a time, rather than all at once. The body can then use these natural sugars for energy. On the other hand, table sugar, candy bars, and sodas release sugar that is absorbed into the bloodstream abruptly. The same is true for some fruits.
- Fiber keeps the absorption of sugar slow and steady. Fiber simply means plant roughage. There is also plenty of fiber in beans and vegetables. It is also in the outer coating of grains, which is retained in whole wheat bread and brown rice, but has been eliminated in white bread and white rice. Animal products have no fiber. To these dietary principles should be added a regimen of regular exercise. Exercising muscles effectively remove sugar from the blood.
In studies using a very-low-fat, plant-based diet, along with regular walking, cycling, or other exercise, 90 percent of people with adult-onset diabetes using oral medications were able to stop them in less than a month. Of those who had been taking insulin, 75 percent no longer needed it. The benefits hold up over the long term, and for many patients, the disease simply remits.4,5 This combined program also dramatically reduces the risk of eye, kidney, and nerve complications.6-8
Diabetic neuropathy is a complication of long-standing diabetes in which malfunctioning nerves cause sharp, burning pain, “pins-and-needles,” or numbness, typically in the lower legs and feet. The cause is presumed to be either poor circulation in the tiny blood vessels that nourish the nerves or a toxic effect that occurs when blood sugar is poorly controlled.
In addition, sugar levels that are out of control may make patients more sensitive to pain. Researchers at the Veterans Administration Medical Center in Minneapolis tested pain tolerance in eight healthy young men. They placed an electrical clip on the web of skin between the first and second fingers on each volunteer. As one of the researchers gradually turned up the voltage to the clip, each subject was asked to report when he could feel any pain and when it became unbearable. An intravenous infusion of sugar (glucose), caused pain sensitivity to increase markedly. The subjects were aware of the pain sooner and experienced it more intensely.9
The same technique was used to test people with diabetes who, of course, generally have higher than normal blood sugars. Their pain sensitivity was much higher than that of people without diabetes.9
The pain of neuropathy can be physically and emotionally debilitating. Pharmacologic therapy relies on strict glucose control, along with antidepressants, which reduce diabetic pain, apparently by reducing neurotransmission in pain nerves.10 They do not improve nerve function, however, and often give only partial relief. Vitamin B-6 has been used as well. At doses of 50-150 milligrams per day, it can reduce pain, although it probably does not improve nerve function. Doses of 200 milligrams or higher should be avoided, as they are associated with worsening neuropathy.11
A nutrition/exercise study brought new optimism to this difficult condition. Milton Crane, M.D., of the Weimar Institute in Weimar, California, studied 21 patients who had developed painful neuropathies in their legs and feet after having had adult-onset diabetes for many years. By using a diet that eliminated all animal products and kept vegetable oils to a minimum, along with regular exercise, leg pains disappeared in 17 patients within two weeks, while the four remaining patients had partial relief. Five patients stopped all their diabetes medicines and the remaining patients cut their doses by about half.12
We assume that plant products stop nerve pains by bringing diabetes under better control. However, complex carbohydrates also stimulate the production of two neurotransmitters that are involved in mood and pain control: noradrenaline and serotonin. These are the same chemicals that antidepressants are designed to increase, and, as we have seen, antidepressants can be helpful in treating diabetic nerve pain. Whether or not this helpful adjustment of neural chemistry gets some of the credit for the disappearance of leg pains is unknown.
Although everyone who has diabetes should be prescribed a combination of a therapeutic diet and regular exercise, a study conducted by Andrew Nicholson, M.D., of the Physicians Committee for Responsible Medicine, isolated the effect of diet alone for research purposes, in order to assess what kind of diet is best.
Like Dr. Crane, Dr. Nicholson’s study used a vegan diet without added vegetable oils, but did not recommend any exercise program at all. The results were tabulated three months later. The patients’ blood sugars dropped 54 points on a vegan diet, compared to less than half this amount on a more traditional low-fat diet. Although subjects were not limiting calories, the average weight loss over the three-month study was 16 pounds, compared to only 8 pounds on the more usual diet. Kidney abnormalities also improved dramatically.13
In summary, older diets for people with diabetes were not very powerful. Low-fat, unrefined vegetarian diets often bring dramatic results. Adding exercise to the regimen will bring further benefits, because working muscles pull sugar out of the blood, even with very little insulin present.
It is clear which foods help insulin to work better. Vegetables and beans are generally between 4 percent and 10 percent fat, and all are high in complex carbohydrates and natural fiber. Whole grains, such as brown rice and whole grain bread, are also very low in fat and have plenty of complex carbohydrates and fiber, so long as they are not refined into fiber-depleted white rice, white bread, etc.
Fruits are very low in fat and high in fiber, although their sugars are absorbed more quickly than those in starchy plants.
Animal products provide no benefits for people with diabetes. All meats—even chicken breast without the skin—contain a significant amount of fat, and no animal products have any complex carbohydrate or fiber. They not only erode glycemic control; they also encourage the atherosclerosis and vascular damage that are the greatest risks people with diabetes face.
An optimal diet eliminates animal products completely and also keeps vegetable oils to a bare minimum. By prescribing diets using generous amounts of vegetables, grains, and bean dishes, while avoiding animal products and added oils, researchers have found that they do not need exchange lists to keep blood sugar under control, and there is no need to limit portion size.
- Encourage your patients to follow a low-fat vegan (pure vegetarian) diet, avoiding all animal products and added oils. If this kind of diet is new for them, encourage them to try it very strictly for three weeks, and always refer them to a dietitian for assistance. A three-week period gives them plenty of time to experiment with different foods, without the daunting feeling of a long-term commitment. At three weeks, the benefits are usually so obvious that patients are strongly motivated to continue.
- Encourage patients to focus on foods that are rich in complex carbohydrates and fiber: beans, vegetables, and whole grains, rather than those whose fiber has been removed (e.g., white bread, pasta, and white rice).
- To insure complete nutrition, it is important to have a source of vitamin B12, which could include any common multivitamin, fortified soymilk or cereals, or a vitamin B12 supplement of 5 micrograms or more per day.
- Regular exercise should be encouraged, within the limits patients can tolerate. A half-hour walk every day or one hour three times per week is a good regimen for most people, and they can do more as their exercise capacity increases.
- Monitor patients’ glucose levels frequently during the period of diet change or increasing exercise. They have a powerful hypoglycemic effect that usually necessitates a prompt reduction in medications.
For patients with continuing symptoms of neuropathy despite an optimal diet/exercise regimen, vitamin B-6, 50-150 milligrams per day, can be used as a nutritional adjunct. Avoid higher doses.
- How could cow’s milk protein influence the risk for development of diabetes?
- What may be some practical solutions to this problem?
- What are desirable feeding practices for infants that you would like to consider?
- What kinds of diets would be most effective in helping your patients achieve glycemic control?
- What dietary recommendations should you provide to your patients?
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13. Nicholson AS, Sklar M, Gore S, Sullivan R, Browning S. The very-low-fat, high-fiber diet in treatment of NIDDM: a randomized, controlled, intervention study. 1997, In press.