Eating traditionally harvested fish may prevent type 2 diabetes in First Nations communities

In Canada, the rates of type 2 diabetes in First Nations communities are up to five times higher than for other Canadians. Type 2 diabetes is a life-long disease characterized by high blood sugar and insulin resistance, increasing risk of disabling health complications including cardiovascular and kidney disease. Genetics and lifestyle factors such as being overweight and obese, low physical activity, smoking, and unhealthy diet are the most common causes of type 2 diabetes.

Researchers suggest that high consumption of fish may reduce the risk of developing type 2 diabetes. Potential benefits of eating fish are linked to “good” fats such as omega-3 fatty acids which may lower the levels of “bad” cholesterol and lipids, and improve insulin sensitivity.

In First Nations communities, fish is traditionally harvested from the local natural environment. This traditional food provides First Nations with energy and essential nutrients including omega-3 fatty acids. However, locally harvested fish may also contain chemical contaminants such as PCBs (polychlorinated biphenyls). These types of contaminants are highly resistant to breakdown in the environment and build up in living organisms, including humans. They also have several detrimental health effects and can cause type 2 diabetes.

Our study aimed to understand the relationship between fish consumption and type 2 diabetes. We interviewed 706 First Nations adults living in 8 communities in Manitoba, Canada. The participants were asked to report their fish consumption habits and diagnosis of type 2 diabetes. Levels of contaminants were then measured in fish species consumed by First Nations communities and levels of omega-3 fatty acids in fishes were determined using the Canadian File of Nutrients database.

The data revealed that people who consumed at least one portion (150 g)of fish per week (equal to two servings of fish per week as recommended by Canada’s Food Guide) were 60% less likely to be diagnosed with type 2 diabetes compared to those who did not consume fish. Likewise, consumption of omega-3 fatty acids from fish was associated with 50% lower risk of type 2 diabetes reported. Fish species commonly consumed in Manitoba First Nations were walleye, northern pike, lake whitefish, and lake trout. We found that levels of contaminants in these species of fish were very low, and exposure to these contaminants through diet was not associated with reported type 2 diabetes.

Although our study did not determine a causal effect between fish consumption and type 2 diabetes, our results provide evidences that eating traditionally harvested fish and consuming omega-3 fatty acids has a beneficial health effect in First Nations communities in Manitoba.

Read the full paper — Fish consumption is inversely associated with type 2 diabetes in Manitoba First Nations communities by Lesya Marushka, Malek Batal, Donald Sharp, Harold Schwartz, Amy Ing, Karen Fediuk, Andrew Black, Constantine Tikhonov and Hing Man Chan on the FACETS website.