PSI-4 - Beef Fat Enriched with Vaccenic Acid and cis9,trans11-conjugated Linoleic Acid Promotes Hepatic Steatosis and Glucose Intolerance in High-fat-fed C57BL/6 Mice

Abstract: Vaccenic acid (VA, trans11-18:1) and cis-9, trans11-conjugated linoleic acid (also known as rumenic acid; RA) have received widespread attention as “beneficial” trans fatty acids (TFA) due to their putative health benefits including anti-diabetic properties. Feeding oilseeds (e.g. sunflower seeds or flaxseeds) to cattle given forage-based diets have been shown to enrich their meat and milk fat with VA and RA. However, there is shortage of studies evaluating the health effects of the resulting enriched fat. The objective of the present experiment was to determine the effects of beef fat enriched with VA and RA on parameters related to glucose and insulin tolerance in in high-fat-fed C57BL/6 Mice. Thirty-six 8-week-old male c57/6J mice (25±1.4 g body weight) were randomly assigned for 18 weeks to either a control low fat diet (CLF; 10% total calories from fat), a control high fat diet based on lard (CHF; 45% total calories from fat), or a VA&RA-enriched high fat diet based on flaxseed-fed beef fat (EHF, 45% total calories from fat). Compared with CLF, feeding either CHF or EHF resulted in negative metabolic outcomes associated with high fat diets including adiposity, impaired insulin and glucose tolerances, and hepatic steatosis. However, the EHF diet induced a higher (P < 0.05) liver weight and liver triglyceride content compared with the CHF diet. In addition, the area under the curve for glucose tolerance test (GTT) in EHF mice was higher (P < 0.05) than in CHF group. Collectively, the findings from this study, suggest that feeding beef fat enriched with VA and RA (i.e. EHF) worsens glucose tolerance and liver steatosis in high-fat-fed mice. Additional studies are needed to determine if the adverse effects of EHF on glucose tolerance and liver fat accumulation are related to VA and RA or due to other TFA present in EHF.