Type 2 Diabetes: Supplements Overview
5. What is known about the safety and effectiveness of these six dietary supplements as CAM treatments for diabetes? continued...
Omega-3 Fatty Acids
Omega-3 fatty acids (omega-3s, for short) are a group of polyunsaturated fatty acids that come from food sources, such as fish, fish oil, some vegetable oils (primarily canola and soybean), walnuts, wheat germ, and certain dietary supplements. As supplements, omega-3s are marketed as capsules or oils, often as fish oil.
Omega-3s are important in a number of bodily functions, including moving calcium and other substances in and out of cells, the relaxation and contraction of muscles, blood clotting, digestion, fertility, cell division, and growth. Omega-3s have been the subject of much media attention in recent years, because of studies finding they may be useful for such purposes as decreasing the rate of heart disease, reducing inflammation, and lowering triglyceride levels. Some countries and organizations have issued formal recommendations on the intake of omega-3s, through meals, oils, and possibly supplementation. Omega-3s have been of interest for diabetes primarily because having diabetes increases a person's risk for heart disease and stroke.
Summary of the research findings
Randomized clinical trials have found that omega-3 supplementation reduces the incidence of cardiovascular disease and events (such as heart attack and stroke) and slows the progression of atherosclerosis (hardening of the arteries). However, these studies were not done in populations that were at higher risk, such as those with type 2 diabetes.
With regard to studies on omega-3 supplementation for type 2 diabetes, there is somewhat more literature available than for most other CAM therapies for this condition. A 2001 analysis was published by the Cochrane Collaboration, of 18 randomized placebo-controlled trials on fish oil supplementation in type 2 diabetes. The authors found that fish oil lowered triglycerides and raised LDL cholesterol but had no significant effect on fasting blood glucose, HbA1c, total cholesterol, or HDL cholesterol. (The authors did not identify and include studies with cardiovascular outcomes, but noted that this is an area for further research.) Another analysis was published in 2004 by the Agency for Healthcare Research and Quality, of 18 studies on omega-3 fatty acids for a number of measurable outcomes in type 2 diabetes. This study confirmed virtually all the Cochrane authors' findings, except for finding no significant effect on LDL cholesterol.