Obesogenic diets enriched in oleic acid vs saturated fatty acids differentially modify polyunsaturated fatty acid composition in liver and visceral adipose

Abstract

Emerging evidence indicates that the fatty acid composition of obesogenic diets impacts physiologic outcomes. Much attention is focused on the biologic effects of consuming monounsaturated fatty acids (MUFA) vs saturated fatty acids (SFA). We investigated the extent to which an obesogenic diet high in MUFA vs SFA modified lipid composition in liver and visceral adipose tissue with a focus upon polyunsaturated fatty acids (PUFA).Adult male mice were fed (8 wks) (1) a control 16% fat energy (en) diet with 6% en MUFA as oleic acid (18:1n‐9) and 4 % en SFA, (2) a 50% fat en high MUFA diet with 33% en MUFA and 10% en SFA, or (3) 50% a high SFA diet with 9% en MUFA and 33% en SFA. Intake of linoleic acid (LA; 18:2n‐6) and alpha‐linolenic acid (ALA;18:3n‐3) were kept constant at 3% en and 2% en, respectively. By the end of the study, mice on the high MUFA diet were heavier with a higher total fat content and liver mass than the control mice.Total hepatic fatty acid content was elevated (78%) in the high MUFA group only, mostly as a result of oleic acid (18:1n‐9) in the neutral lipid fraction. ALA content was lower (30%) in the high MUFA group than the low fat and high‐SFA‐fed mice. However, both high fat diets elevated hepatic content of arachidonic acid (ARA; 20:4n‐6) by 10% and docosahexaenoic acid (DHA; 22:6n‐3) by 48% (MUFA group) and 22% (SFA group).Epididymal adipose tissue mass was 45% higher in both high fat groups than the control group. When evaluated as amount/gram tissue, the content of LA, ALA, ARA, and DHA was reduced by both high fat diets. However, the high MUFA diet caused a greater reduction in ALA and LA than the SFA diet. Normalizing PUFA content to the entire adipose depot mass removed the reductions in ARA and DHA in both groups. While normalization yielded similar levels of ALA and LA in the SFA group compared to the controls, ALA and LA contents were still lower in the entire epididymal adipose pool in the MUFA group.These data indicate that dietary MUFA and SFA in high‐fat diets impact hepatic and adipose PUFA metabolism. These data indicate that these obesogenic diets, at least in the short term, increase long chain PUFA content in liver. Moreover, these data show that MUFA has selective effects upon PUFA distribution in adipose tissue.Support or Funding InformationUSDA/ARS funding