Diet Rich In Omega 3 Fatty Acids Could Thwart Diabetes Onset

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.

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 Dr. Michael Clare-Salzler, 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, 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, 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.

If further research 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 Dr. Charles Serhan, 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.”

About type 1 diabetes

"Type 1 diabetes mellitus is an autoimmune disease that is characterized by the destruction of insulin-producing beta cells in the pancreatic islets. Although it is not yet known what initiates the autoimmune process, it is likely that both genetic background and environmental factors contribute to the disease process," the authors write. Certain dietary factors have been associated with the onset of type 1 diabetes as well as the autoimmune process that leads to the disease.

Further study details

Jill M. Norris, M.P.H., Ph.D., of the University of Colorado at Denver and Health Sciences Center, Denver, and colleagues examined whether consumption of omega-3 and omega-6 fatty acids are associated with the development of pancreatic islet autoimmunity (IA; development of antibodies against the cells in pancreas that produce insulin) in children.

The study, conducted between 1994 and 2006, included 1,770 children at increased risk for type 1 diabetes, defined as either possession of a high diabetes risk HLA (human leukocyte antigen) genotype or having a sibling or parent with type 1 diabetes. The average age at follow-up was 6.2 years. Islet autoimmunity was assessed in association with reported dietary intake of polyunsaturated fatty acids starting at age 1 year. Fish is the primary source of marine polyunsaturated fatty acids. Childhood diet was measured using a food frequency questionnaire (FFQ).

A case-cohort study (n = 244) was also conducted in which risk of IA by polyunsaturated fatty acid content of erythrocyte membranes (outer portion of the red blood cell) was examined.

Fifty-eight children became positive for IA during follow-up. Adjusting for HLA genotype, family history of type 1 diabetes, caloric intake, and total omega-6 fatty acid intake, total omega-3 fatty acid intake was inversely associated with IA risk (a 55 percent reduced risk). The association was strengthened when the definition of the outcome was limited to those positive for two or more autoantibodies. In the case-cohort study, omega-3 fatty acid content of erythrocyte membranes was associated with a 37 percent decreased risk of IA.

"Our study suggests that higher consumption of total omega-3 fatty acids, which was reported on the FFQ, is associated with a lower risk of IA in children at increased genetic risk of type 1 diabetes," the researchers write.

Reference: JAMA. 2007;298(12):1420-1428.

Funding came from the National Institutes of Health and the University of Colorado’s Diabetes Endocrine Research Center.