medwireNews: People with higher levels of linoleic acid biomarkers have a reduced risk for type 2 diabetes than those with lower levels, whereas its metabolite arachidonic acid is not significantly associated with type 2 diabetes risk, study results suggest.
“Several dietary guidelines recommend increased linoleic acid consumption to improve blood cholesterol levels and reduce cardiovascular risk,” explain Jason Wu (University of New South Wales, Sydney, Australia) and fellow researchers.
“Our analysis provides novel findings that, when combined with in-vitro experimental and shorter-term interventions for metabolic risk factors, suggest that linoleic acid has an additional role for prevention of type 2 diabetes in healthy populations,” they add.
As reported in The Lancet Diabetes & Endocrinology, the team carried out a pooled analysis of individual participant data from 20 observational studies including 39,740 participants who were free from diabetes at baseline, 11% of whom developed type 2 diabetes over 366,073 person–years of follow-up.
After multivariable adjustment, there was a “substantial” inverse association between linoleic acid and type 2 diabetes, with participants in the highest quintile for linoleic acid biomarker levels having a significant 43% lower risk for developing diabetes than those in the lowest quintile.
And this inverse association was “generally similar” when different lipid compartments – including phospholipids, plasma, and cholesterol esters – were analyzed separately, “suggesting a class effect of linoleic acid rather than primacy of any single compartment,” say the researchers.
On the other hand, there was no significant association between overall levels of arachidonic acid biomarkers and the incidence of type 2 diabetes. These findings were consistent when arachidonic acid levels from separate lipid compartments were analyzed, with the exception of plasma. Participants with plasma arachidonic acid levels in the highest quintile had a significant 36% reduced risk for diabetes than those with levels in the lowest quintile.
The author of an accompanying commentary, Gabriele Riccardi (Federico II University, Naples, Italy) describes these findings as “reassuring” given that “[s]ome researchers have proposed that linoleic acid could have harmful metabolic effects if converted to arachidonic acid, which might have proinflammatory activity favouring diabetes development.”
Riccardi cautions that the study findings “cannot immediately be extrapolated to linoleic acid intake,” but believes that the difference in diabetes risk observed with varying linoleic acid levels “would be consistent with linoleic acid intake corresponding to one serving of nuts or one spoonful of sunflower or corn oil daily.”
And he concludes: “The effect of dietary linoleic acid on diabetes incidence should now be tested in a randomised, controlled intervention trial.”
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