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Polyunsaturated fats may counter cardiometabolic effects of weight gain in healthy adults
Excess energy from polyunsaturated fatty acids reduced atherogenic lipoproteins compared with saturated fatty acids in healthy young adults who experienced short-term modest weight gain, according to research published in the Journal of the American Heart Association.
The hyperproinsulinemia and increased biomarkers of endothelial dysfunction induced by the extra pounds could be partially offset by the lipid-lowering effects seen with the consumption of polyunsaturated fatty acids, researchers in Sweden found.
“Even modest weight gain, caused by a diet relatively high in fat, can impair glucose metabolism and, to some extent, also vascular function in young and lean individuals,” Ulf Risérus, MMed, PhD, of Uppsala University, Sweden, told Endocrine Today. “However, to replace some of the saturated fats in the diet with polyunsaturated fats from vegetable oils can counteract some of the adverse cardiometabolic effects caused by weight gain and caloric access.”
Ulf Risérus
Risérus, along with David Iggman, MD, a PhD student at the university, and colleagues conducted a 7-week, double blind, parallel-group, randomized controlled trial involving 39 healthy, lean adults (mean age, 27 years) to determine whether certain dietary fats could alter cardiometabolic responses to a hypercaloric diet.
Patients consumed muffins with 51% of energy from fat and 44% of energy from refined carbohydrates that added 750 kcal/day to their usual diets. All muffins had identical ingredients, except for the fat; either sunflower oil rich in polyunsaturated fatty acids (PUFA diet) or palm oil rich in saturated fatty acids (SFA diet) was used.
David Iggman
Comparable weight gain was seen in both groups, but decreases were seen with PUFA vs. SFA in total HDL cholesterol (–0.37 vs. 0.07; P=.003), LDL:HDL cholesterol (–0.31 vs. 0.05; P=.007) and apolipoprotein B:ApoA-I (–0.07 vs. 0.01; P=.01) ratios; no significant between-group differences were observed for other cardiometabolic risk markers.
Independent of oil type used, body weight increased (2.2%; P<.001) along with increased plasma proinsulin (21%; P=.007), insulin (17%; P=.003), PCSK9 (9%; P=.008), fibroblast growth factor 21 (31%; P=.04), endothelial markers vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin (9%, 5% and 10%, respectively; P<.01 for all), whereas nonesterified fatty acids decreased (–28%; P=.001).
“We show for the first time that unsaturated fats can improve blood lipid profile despite conditions of energy excess on moderate weight gain,” Risérus said. “It was also surprising to see that even a modest weight gain of 1.4 kg in lean, young individuals clearly increased markers of insulin resistance as well as signs of impaired vascular function.”
Risérus said these early adverse effects resulting from a diet rich in calories from fat could explain some of the well-known associations between obesity and increased diabetes and cardiovascular disease risk in the long term.
“As more than half of the Western populations consume an excessive amount of calories and gain weight over time, these results are clearly relevant and suggest that regular intake of vegetable oils and nuts are of some benefit also in subjects gaining weight,” Risérus said. – by Allegra Tiver
For more information:
Risérus can be reached at the Department of Public Health and Caring Sciences, Clinical Nutrition and Metabolism, Uppsala Science Park, 75185 Uppsala, Faculty of Medicine, Uppsala University, Sweden; email: Ulf.riserus@pubcare.uu.se.
Disclosure: This study was mainly funded by the Swedish Research Council, with support from the Swedish Society of Medicine, Lennanders Foundation and Uppsala-Örebro Regional Research Council. One researcher received support from the Stockholm and Uppsala City Council, Swedish Research Council, the Swedish Heart-Lung and the Diabetes Foundations, the Foundation Leducq, and Cardiovascular Program, Karolinska Institute/Stockholm City Council.
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Iggman D. J Am Heart Assoc. 2014;doi:10.1161/JAHA.114.001095.