Metabolic markers in Ossabaw pigs fed high fat diets enriched in regular or low α-linolenic acid soy oil.

Background: Soy oil is a major vegetable oil consumed in the US. A recently developed soybean variety produces oil with a lower concentration of α-linolenic acid, hence a higher (n-6)/(n-3) ratio, than regular soy oil. The study was conducted to determine the metabolic impact of the low α-linolenic acid containing soy oil.

Methods: Ossabaw pigs were fed diets supplemented with either 13% regular soybean oil (SBO), or 13% of the low α-linolenic soybean oil (LLO) or a control diet (CON) without extra oil supplementation, for 8 weeks.

Results: Serum and adipose tissue α-linolenic acid concentration was higher in pigs fed the SBO diet than those on the CON and LLO diets. In the serum, the concentration of saturated fatty acids (SFA) was lower in the LLO group than in CON and SBO groups polyunsaturated fatty acid (PUFA) concentration was higher in the LLO group compared to CON and SBO groups. Glucose, insulin, triglycerides and LDL-cholesterol were higher in pigs fed the SBO diet than those fed the CON and LLO diets. HDL-cholesterol was lower in pigs on the SBO diet than those on the CON and LLO diets. Pigs fed SBO and LLO diets had lower CRP concentration than those on the CON diet. Adipose tissue expression of Interleukin 6 (IL-6) was higher in the SBO and LLO diets than the CON. Expression of ECM genes, COLVIA and fibronectin, was significantly reduced in the SBO diet relative to the CON and LLO diets whereas expression of inflammation-related genes, cluster of differentiation 68 (CD68) and monocyte chemoattractant protein 1 (MCP-1), was not different across treatments.

Conclusions: Results suggest that lowering the content of α-linolenic acid in the context of a high fat diet could lead to mitigation of development of hyperinsulinemia and dyslipidemia without significant effects on adipose tissue inflammation.