Eating a diet rich in omega-6 polyunsaturated fats (PUFA) can significantly reduce the risk of developing type 2 diabetes mellitus (T2DM), according to a new study.
Recent studies have suggested that omega-6 fat is harmful to health, possibly due to inflammation leading to an increased risk of chronic diseases. But the new study found those who had the highest blood level of linoleic acid, the major omega-6 fat, were 35% less likely to developT2DM in the future than those who had the least amount.
“This is striking evidence. The people involved in the study were generally healthy and were not given specific guidance on what to eat. Yet those who had the highest levels of blood omega-6 markers had a much lower chance of developing type 2 diabetes,” said senior author Dariush Mozaffarian, of the Friedman School of Nutrition Science and Policy at Tufts University.
The researchers published their results October 11, 2017 in The Lancet Diabetes & Endocrinology.
They analyzed data from 20 prospective cohort studies from ten countries: United States, Iceland, the Netherlands, Germany, Finland, the United Kingdom, Sweden, France, Australia, and Taiwan. Biomarkers were sampled between 1970 and 2010 from phospholipids, total plasma or serum, cholesterol esters, and/or adipose tissue, with measurements performed in more than two lipid compartments in six cohorts.
The study included 39,740 adults with mean patient age range from 49 to 76 years with a body mass index (BMI) of 23.3–28.4 kg/m2 who did not have T2DM at baseline. Over 366,073 person-years of follow-up the researchers identified 4347 cases of incident T2DM.
A multivariable analysis of pooled data showed that higher proportions of linoleic acid biomarkers as percentages of total fatty acid were associated with a lower risk of T2DM overall. The findings were generally similar across different lipid compartments, including phospholipids, plasma, cholesterol esters, and adipose tissue. Arachidonic acid levels were not significantly associated with the risk of developing T2DM.
The associations between linoleic acid and arachidonic acid biomarkers and the risk of T2DM were not significantly modified by any potential confounding factors, including age, BMI, sex, race, aspirin use, omega-3 PUFA levels, or variants of the fatty-acid desaturase (FADS) gene, which is strongly associated with omega-6 PUFA levels.
Omega-6 fat is found in bean and seed oils, such as soybean and sunflower oils, and in nuts. Linoleic acid is not formed in the body and can only be obtained from the diet. US dietary guidelines recommend between 5% to 10% of energy should be derived from polyunsaturated fats. The results suggest that eating foods rich in linoleic acid may lower risk of T2DM, the researchers stated.
In an accompanying editorial, Gabriele Riccardi, MD, department of clinical medicine and surgery, Federico II University, Naples, Italy, stated: "Although this finding cannot immediately be extrapolated to linoleic-acid intake, it seems reasonable to assume that the differences in the linoleic-acid biomarker associated with this outcome would be consistent with linoleic-acid intake corresponding to one serving of nuts or one spoonful of sunflower or corn oil daily.”