Diabetes and Diet
Most people think of a diabetic diet as one with no added sugar (which is no longer true, by the way). But it's not that simple. True, a major study found that people who develop diabetes tend to consume foods with a slightly higher glycemic index than people who don't develop diabetes. The glycemic index is a measure of how much your blood sugar is affected by eating a given food. It turns out that many starchy foods do raise your blood sugar more than other foods. For example, bread, including whole wheat bread, raises your blood sugar as much as white sugar does, and potatoes raise your sugar even more than that.
On the other hand, one recent study showed that women who consume higher amounts of whole grains have a lower risk of developing diabetes as other women. So glycemic index isn't everything. It may just be that the slightly higher glycemic index diet of those developing diabetes simply reflects what we might call a junk food diet -- the standard American diet, high in sugary snacks and fats but low in the complex carbohydrates found in plant foods.
Many studies confirm that a meat-based diet, low in fiber and high in refined foods, is the cause of the epidemic of obesity and diabetes we are now seeing. Seventh Day Adventists, about half of whom are vegetarian, have only half the death rate from diabetes as the rest of the population. The protective effect of a vegetarian diet has been attributed to its high fiber content, and some feel that magnesium, the best sources of which are dark, leafy green vegetables, legumes, whole grains, and nuts, may also play a role.
So what exactly is diabetes? We generally recognize two forms of the disease. Type I diabetes generally requires insulin treatment and was formerly known as juvenile diabetes. It seems to be an autoimmune type of disease, in which the body's immune system destroys the insulin-producing cells of the pancreas. There's some evidence that drinking cow's milk in childhood is a risk factor, but this remains controversial.
Type II diabetes is usually thought of as the adult form of the disease. The pancreas still produces insulin but the body is resistant to its effects. About 80% of type II diabetics are obese. Some think of type II diabetes as the milder form, but type II diabetics develop the same complications as type I diabetics. The good news is that when type II diabetics change their lifestyle -- adopting a high fiber plant-based diet and losing the excess weight -- the diabetes can often be reversed and the need for medication eliminated. Low carbohydrate, high protein diets do not reverse diabetes; they cause it. And they only promote weight loss when they contain a reduced number of calories, just as with any diet.
And this news just in: a study reported in the October 2001 issue of the British Journal of Nutrition found that among non-obese meat-eaters and vegetarians, the vegetarians were more sensitive (less resistant) to the effects of insulin on their blood sugars and therefore less likely to develop type II diabetes!
Evidence for the ideal diet for diabetics also comes from studies of diabetic complications, which usually center on the blood vessels. Heart attacks, strokes, and kidney and eye problems all have to do with the weakening effect of diabetes on blood vessels. In particular, when the kidneys start to go in a diabetic, so do the eyes. The kidneys begin to fail and the eyes develop retinopathy, a condition involving the blood vessels of the retina. Excess protein in the diet leads to earlier kidney failure, and current recommendations for diabetics specify that they consume no more than the recommended dietary allowance for protein, 63 mg a day for men and 50 mg a day for women. The faddish low-carbohydrate high-protein diets now being promoted contain up to double these amounts.
Protein also has a deleterious effect on retinopathy, the cause of poor vision in many people with long-standing diabetes. One study showed that diets that are high in carbohydrate and fiber and relatively low in protein help prevent diabetic retinopathy, whereas diets that are low in carbohydrate and high in protein tend to promote it. It's clear, then, that a vegetarian diet, high in complex carbohydrate and fiber, can not only prevent many people from becoming diabetic but can also prevent complications in those who have the disease.
Meat-based diets harm diabetics in other ways as well. Along with the protein comes a "healthy" dose of cholesterol and saturated fat (what an oxymoron!). One does not need an M.D. degree to know that cholesterol and saturated fat are bad for blood vessels and lead to heart attacks and strokes. But cholesterol is also an important part of the fat-rich leakages in the retina of the eye that can obscure vision. Laser treatments are the usual way of sealing the leaking blood vessels and preserving vision. But at least half a dozen studies over the past fifty years have shown that lowering blood cholesterol levels will often make these leakages clear up, averting the need for laser burns! Unfortunately, diabetics rarely hear about this option.
To summarize, most cases of adult-onset diabetes could be prevented by lifestyle change -- adoption of a vegetarian diet, rich in fiber and complex carbohydrates and relatively low in protein and fat. In people with either type I or type II diabetes, a diet such as this, formulated in consultation with their doctors, could markedly reduce the incidence of serious complications. Corned beef and cabbage? The key is to hold the corned beef and eat the cabbage!