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Polyunsaturated fatty acids confer no benefit for diabetes protection
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Risk for developing type 2 diabetes is not modified by consuming more omega-3, omega-6 and/or total polyunsaturated fatty acids, according to findings published in BMJ.
“The World Health Organization asked us to carry out a set of studies — systematic reviews of randomized controlled trials — assessing health effects of omega-3 and omega-6, which are polyunsaturated fats,” Lee Hooper, PhD, RD, a reader in research synthesis, nutrition and hydration at the Norwich Medical School of the University of East Anglia in Norwich, U.K., told Endocrine Today. “This is because the WHO are planning to update their dietary guidance on fats in the near future.”
Hooper and colleagues conducted a systematic review of 83 randomized controlled trials. The primary variables were several doses of omega-3, omega-6 and total polyunsaturated fatty acids. All trials lasted 24 weeks or longer and recorded changes in glucose, insulin, HbA1c, insulin resistance and the presence of diabetes.
The risk for developing type 2 diabetes was not influenced by long-chain omega-3 consumption, with the RR falling firmly in the range of results that indicated “little or no effect,” according to the researchers. Measures of HbA1c, insulin resistance, fasting serum insulin and fasting glucose did not change to a statistically significant degree with more long-chain omega-3 either, although the researchers noted that consuming at least 4.4 g per day resulted in signs of elevating diabetes risk, HbA1c, insulin resistance and glucose levels.
“Honestly, I was hugely relieved not to see any harm,” Hooper said. “There have been worries about negative effects of long chain omega-3 on diabetic risk and control. [People with diabetes] are more likely to have raised triglycerides and so be prescribed long-chain omega-3 fats to reduce them, so the effects on diabetes risk and control are important.”
HbA1c, insulin resistance and fasting glucose levels did not change significantly with more alpha-linolenic acid consumption, according to the researchers, who added that it was “uncertain” whether the acid would influence diabetes development even if fasting insulin appeared to rise in those who consumed more.
Results were either “unclear” or supported “little or no effect” on diabetes development, insulin resistance, HbA1c and fasting glucose when examining studies that substituted omega-3 for omega-6 with similar ambiguity found in studies purely examining omega-6 on its own and total polyunsaturated fatty acids.
“This is definitive — taking fish oil supplements does not protect against diabetes, but neither is it harmful except possibly at high doses.” Hooper said. – by Phil Neuffer
For more information:
Lee Hooper, PhD, RD, can be reached at L.Hooper@uea.ac.uk.
Disclosures: This research received financial support from the University of East Anglia and WHO.
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