Dietary fatty acids may help prevent diabetes

Sep 27 2007

Omega-3 fatty acids have long been touted for their heart-healthy and brain-boosting benefits. Consider cod liver oil, fortified infant formula and enriched eggs.

Now a study of nearly 1,800 children at risk for type 1 diabetes has found that increased consumption of dietary omega-3 fatty acids appears to reduce the risk of the body attacking its own insulin-producing cells, a precursor to this form of the disease, report researchers at the University of Colorado and the University of Florida.

The findings appear in the Sept. 26 issue of the Journal of the American Medical Association.

In the past few decades, there has been a dramatic rise in the incidence of type 1 diabetes, both in the United States and in Europe — a jump that coincides with changes in food manufacturing that have led to a decline in omega-3 fatty acids in the diet and an increase in the content of omega-6 fatty acids, said Michael Clare-Salzler, M.D., a professor and the Stetson chair in experimental pathology at the University of Florida College of Medicine.

“The foods we are eating now are qualitatively much different than those produced on a 1900s-era farm,” Clare-Salzler said. “When animals are commercially raised today, they are often fed grains rich in omega-6 fatty acids, fatty acids that can promote inflammation. In the old days, animals received a much more balanced intake of omega-3 and omega 6-fatty acids.”

The amount of omega-3 fatty acids found in food today has dropped 28-fold from 100 years ago, Clare-Salzler said. In contrast to the omega-6 variety, omega-3 fatty acids have potent anti-inflammatory effects.

“Animal studies have shown inflammation in the insulin-producing cells of the pancreas is an early event that leads to type 1 diabetes,” said Clare-Salzler, who also directs UF's Center for Immunology and Transplantation. “From these studies in mice, it appears if you thwart inflammation you can prevent the disease from occurring. The human parallel in this study indicates that higher dietary intake of anti-inflammatory omega-3 fatty acids reduces the risk of developing an immune response to the insulin-producing cells.”

Scientists set out to study whether increased intake of omega-3 fatty acids would be associated with prevention of or delay in the emergence of autoantibodies in the blood that signal the immune system's attack on insulin-producing cells. Children enrolled in the Denver-based Diabetes Autoimmunity Study in the Young, or DAISY, were all at increased risk for type 1 diabetes and were evaluated until they were, on average, 6 years old.

Their parents were asked annually to report what they ate, including how often they consumed canned tuna, dark-meat fish such as salmon, other fish, shrimp, lobster and scallops, and also what kind of fat was used in cooking. Blood samples also were taken to test study participants for the presence of autoantibodies, and Nancy J. Szabo, Ph.D., director of the Analytical Toxicology Core Laboratory at UF's College of Veterinary Medicine, evaluated the fatty acid composition of red blood cell membranes isolated from blood samples taken from a subset of 244 children.

“Kids who had higher intakes of omega-3 fatty acids had a significant reduction in the risk of development of autoantibodies,” Clare-Salzler said, adding that the risk of developing the autoantibodies also went down as the concentration of omega-3 fatty acids rose in the red blood cells.

All fatty acids help bolster the structure and function of cell membranes, but omega-3 fatty acids strongly support the production of anti-inflammatory molecules than can quell an immune attack on insulin-producing cells, Clare-Salzler said.

The study's lead author was Jill M. Norris, Ph.D., M.P.H., a professor of preventive medicine and biometrics at the University of Colorado at Denver's School of Medicine. Funding came from the National Institutes of Health and the University of Colorado's Diabetes Endocrine Research Center.

UF and University of Colorado researchers are continuing to explore links between diabetes and diet. Clare-Salzler and Peter Chase from the University of Colorado's Barbara Davis Center for Childhood Diabetes are leading a National Institutes of Health-funded multicenter pilot trial, the Nutritional Intervention to Prevent Type 1 Diabetes, or NIP, to examine whether babies who receive dietary supplementation with the omega-3 fatty acid docosohexaenoic acid, or DHA, show fewer signs of inflammation. An expanded version of the trial will then determine whether DHA protects infants and children from the development of autoantibodies that lead to diabetes in comparison with babies who receive standard formula or diets with a much lower level of the omega-3 fatty acid.

If the trial confirms the hypothesis that dietary supplementation with DHA in infancy blocks early inflammatory events key to diabetes development, then, the authors write in JAMA, “dietary supplementation with omega-3 fatty acids could become a mainstay for early intervention to safely prevent the development of type 1 diabetes.”

“The compounds that are made from the omega-3s are natural, the body's own protective mechanisms for overt inflammation,” said professor Charles Serhan, M.D., director of the Center for Experimental Therapeutics and Reperfusion Injury at Harvard Medical School. “What these results say is that you may now be able to add back through the diet these essential omega-3 fatty acids, and then they will be utilized by the body to generate its own set of protective molecules that help to instruct the immune cells in the local environment not to attack the insulin-producing islets cells in the pancreas … these are very powerful and potentially very important results.”