A recent study has linked fish oil supplements to an increase in a beneficial hormone that boosts sugar metabolism (a key factor in diabetes prevention).
Though fish oil has been shown to increase this hormone, further studies are needed to establish that fish oil has a direct effect on blood sugar and diabetes.
"Ask your primary care pharmacist about supplements."
This study was conducted by Jason Wu, PhD, from the Harvard School of Public Health, along with collaborators from other institutions in the United States and Australia.
Omega-3 fatty acids, a main ingredient in fish oil capsules, have been shown to have positive effects on the body's ability to process glucose (sugar) and in preventing atherosclerosis or hardening of arteries.
Some studies have demonstrated a lower risk of type 2 diabetes with higher levels of a hormone called adiponectin.
A recent study has linked this hormone to fish oil consumption, suggesting that fish oil likely leads to an increase in adiponectin which in turn has beneficial effects.
The objective of this study was to find out if omega-3 fatty acids (n-3-PUFAs) affect levels of adiponectin.
The researchers studied results from 14 randomized clinical trials that included both a study group (682 subjects) treated with fish oil and a control group (641 subjects) treated with a placebo, which is basically an inert medication with no effects. In this case, the placebos were mainly olive and sunflower oils. Adiponectin levels in the blood were measured for both groups.
In the group taking fish oil, adiponectin was increased by 0.37 μg/mL which, on statistical analysis, was found to be a significant rise. For the two trials that investigated fish in the diet instead of fish oil supplementation, the effect on adiponectin levels was not significant.
The adiponectin increases were not similar across studies, suggesting that the effects of fish oil may vary in different populations. But the researchers acknowledged that these differences were not significant enough to base decisions on.
Overall, the researchers concluded that fish oil supplementation caused modest increases in adiponectin in the blood stream.
“Although higher levels of adiponectin in the bloodstream have been linked to lower risk of diabetes and coronary heart disease, whether fish oil influences glucose metabolism and development of type 2 diabetes remains unclear,” said Dr. Wu.
“However, results from our study suggest that higher intake of fish oil may moderately increase blood level of adiponectin, and these results support potential benefits of fish oil consumption on glucose control and fat cell metabolism.”
Since this was a study conducted by collecting data from other studies, the researchers noted evidence of publication bias and differences in quality between various studies.
Actual randomized studies need to be conducted to further strengthen the link between fish oil and adiponectin.
The researchers also suggested the need for studies examining the effects of fish oil on aspects such as inflammation, fatty acid levels and insulin resistance, a condition where the body does not respond to insulin.
According to nutrition and preventive Medicine expert, Deborah Gordon, MD, “Though the level of statistical significance and study size are not confidence inspiring, we know from other work that adiponectin levels are inversely associated with the tendency to get type 2 diabetes."
"In my practice, I encourage patients with any complaint, and certainly those fending off type 2 diabetes, to supplement with fermented cod liver oil, a stable source of the highly fragile omega 3 fatty acids in fish oil, combined with the often deficient fat-soluble vitamins, D, A, and K - all of which are useful to patients concerned about metabolic syndrome,” says Dr. Gordon who was not involved in the study.
The results of this study were published in May in The Journal of Clinical Endocrinology and Metabolism.
The study was supported by the National Heart, Lung and Blood Institute, the Canadian Institutes of Health Research and Australian National Heart Foundation Overseas.
Dariush Mozaffarian, one of the co-authors reported receiving travel reimbursements, consulting fees and research grants from various organizations and companies in the food and healthcare industries.
The other two authors did not disclose any conflicts of interest.