Omega-6 polyunsaturated fatty acids and risk of type 2 diabetes

What is it about?

We analyzed the serum fatty acid concentrations of 2,189 middle-aged and older men living in Kuopio and its surrounding areas in Eastern Finland in 1984-1989. During a follow-up of 19 years, 417 men were diagnosed with type 2 diabetes. We found that high serum omega-6 polyunsaturated fatty acid concentrations were associated with a 46% lower risk of developing type 2 diabetes during the follow-up. When analysing the independent associations of different omega-6 polyunsaturated fatty acids, a similarly significant association was found between high serum linoleic and arachidonic acid concentrations and a lower risk of type 2 diabetes. However, high serum gamma-linolenic and dihomo-γ-linolenic acid concentrations were linked to a higher risk. We also found that higher serum concentration of zinc, which is an important cofactor in the metabolism of omega-6 and omega-3 polyunsaturated fatty acids, had an impact on the concentrations of omega-6 polyunsaturated fatty acids in the serum and modified the associations of gamma-linolenic acid and arachidonic acid with the risk.

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Why is it important?

It has been speculated that a high intake of omega-6 polyunsaturated fatty acids may increase the risk of several chronic diseases, as these fatty acids have been suggested to promote low-grade inflammation, among other things. However, studies conducted on humans have not established a link between even a high intake of omega-6 fatty acids and inflammation. Furthermore, omega-6 fatty acids have beneficial effects on, for example, glucose metabolism. Earlier research has systematically linked especially linoleic acid, which is the most common omega-6 fatty acid, to a reduced risk of cardiovascular diseases and type 2 diabetes. However, scientific evidence relating to the health effects of other omega-6 polyunsaturated fatty acids is not as inconclusive, so the results from this study shed some light on this issue. The serum linoleic acid concentration is determined by the person’s diet, and the main sources of linoleic acid are vegetable oils, nuts and seeds. Arachidonic acid is present in meat and eggs; however, the human body can also make arachidonic acid from linoleic acid. Gamma-linolenic acid and dihomo-gamma-linolenic acid are mainly formed in the human body from linoleic acid. Their concentrations in serum are very low in comparison to, for example, linoleic acid. It is not very well known why these two minor fatty acids are associated with a higher risk of type 2 diabetes.

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