Fish Pollutants Linked to Diabetes

Omega-3 fatty acids have been linked to a wide-range of health benefits, including cardiovascular disease (CVD), good development of a baby during pregnancy, joint health, behaviour and mood, and certain cancers.

However, the risk of pollutants from oily fish, such a methyl mercury, dioxins, and polychlorinated biphenols (PCBs) have led to some claims to reduce fresh fish intake, especially for pregnant women who may damage the development of their babies.

Such advice has seen the number of omega-3 enriched or fortified products on the market increase. Most extracted fish oils are molecularly distilled and steam deodorized to remove contaminants.

The researchers behind the new study, from Kyungpook National University and the University of Minnesota, report that the action of POPs may be critical during the early stages of diabetes development. The pesticides are reported to be stored in fatty tissue, which might suggest why overweight and obese people are more susceptible to diabetes, said the researchers.

The study, led by Professor Duk-Hee Lee observed a link between POP levels and diabetes, with obese people with low blood levels of POPs had lower incidence of diabetes.

Such an observation does not prove a causal link, however, meaning that increased POP blood levels do not necessary cause insulin resistance. Indeed, the researchers note that insulin resistance may reduce the body's ability to expel POPs, leading to the build up.

Commenting independently on the research, Matt Hunt, head of science information at British charity Diabetes UK, said: "Insulin resistance is often observed as an early warning sign for developing diabetes and therefore possible contributors to this state are always of interest.

"However, this particular research paper appears extremely complex and speculative and it is not clear how substances such as organochlorines are contributing to the development of insulin resistance.

"Neither would it explain the global rises in obesity and Type 2 diabetes. At the moment we would not conclude that the rise of obesity can be attributed to pesticide use and should still be put down to increasingly unhealthy diets and lack of exercise." 

Source: Diabetes In Control: Diabetes Care, April 2007: "Extended analyses of the association between serum concentrations of Persistent Organic Pollutants and Diabetes" Authors: D.-H. Lee, I.-K. Lee, M. Steffes, and D.R Jacobs, Jr.