Soy Protein and Type 2 Diabetes
People with adult-onset diabetes (also called type 2 or non-insulin-dependent diabetes) and decreased kidney function who consume soy protein on a regular basis may see improvements in their kidney function and cholesterol levels, according to a preliminary study in European Journal of Clinical Nutrition (2003;57:1292–4). Reductions in cholesterol levels may reduce the risk of heart disease, a common complication in people with diabetes.
Adult-onset diabetes has become a worldwide epidemic affecting more than 16 million people in the United States and 135 million people around the world. An estimated 300 million individuals will be affected worldwide by the year 2025. Adult-onset diabetes is associated with several complications, such as heart disease, kidney disease, blindness, and circulation problems. Studies show that the risk of developing adult-onset diabetes is increased by excessive alcohol consumption, smoking, obesity, and sedentary lifestyle. Some physicians believe that dietary factors—particularly the consumption of large amounts of refined grains and sugar—may also play a significant role in the development of diabetes.
In the new preliminary study, 14 adult-onset diabetics with kidney disease were asked to follow a standard diet in which 70% of protein was derived from animal sources and 30% from vegetable sources for seven weeks. Participants then switched to a diet in which 35% of protein was derived from soy, 30% from vegetable sources, and 35% from animal sources for an additional seven weeks. A 24-hour dietary recall questionnaire was completed every two weeks to ensure participants were following the prescribed diets. Blood levels of total cholesterol, LDL cholesterol (“bad” cholesterol), HDL cholesterol (“good” cholesterol), triglycerides, and blood urea nitrogen and creatinine (markers of kidney disease severity) were taken periodically during the study.
Significant decreases in total cholesterol, LDL cholesterol, and triglycerides were observed in those consuming the soy protein diet by 13%, 6%, and 10%, respectively, compared with those consuming the diet that did not contain soy protein. Blood urea nitrogen also decreased while consuming soy protein, suggesting better kidney function. No significant change was seen in HDL cholesterol while participants followed the soy protein diet. These findings suggest that the type of protein consumed may be an important factor in the development of diabetes-related complications.
Other studies have shown that soy protein, in amounts of approximately 25 grams per day, lowers total cholesterol and LDL cholesterol. Soy protein can be found in soy milk, whole soybeans, and tofu. Despite its potential benefits, eating too much soy can promote the development of iron deficiency and may interfere with thyroid function. People who eat soy foods frequently should consult their physician periodically to monitor iron status and thyroid function.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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