Dietary Flax Oil Enriches Adipose Tissue Phospholipids in Long Chain n‐3 PUFA and Reduces Adiposity

Abstract

Consumption of diets enriched in long‐chain omega‐3 polyunsaturated fatty acids (LC n‐3 PUFA) has been associated with reduced adiposity and metabolic benefits in humans and animals, including poultry. Avians express unique elongase enzymes that, relative to humans, enhance their capacity to produce eicosapentaenoic acid (EPA, 20:5, n‐3) and docosahexaenoic acid (DHA, 22:6, n‐3) from alpha‐linolenic acid (ALA; 18:3, n‐3). We tested the hypothesis that enriching adipose tissue in ALA would reduce adiposity in broiler chickens by activating lipid‐responsive nuclear receptors and upregulating expression of genes involved in fatty acid oxidation, comparable to what we have previously found for fasting (Ji et al., 2012). Cobb 500 broiler chicks were fed isocaloric diets containing either 8% flaxseed oil (flax) or 8% lard from hatch to 21 days of age (DS1), or from 21‐42 days of age (DS2). Adipose neutral lipid fatty acid profiles reflected the dietary fat composition. Both EPA and DHA were undetectable in adipose phospholipids (PL) from the lard group but were present in birds consuming flax, while arachidonic acid was increased in PL of the lard group. In both DS1 and DS2, flax diets significantly (p<0.05) reduced adiposity and abdominal adipose weight, with no effect on body weight. Plasma non‐esterified fatty acid (NEFA) levels were significantly lower in flax vs. lard birds in both studies (p=0.0062, DS1 and p=0.014, DS2). Despite the significant reduction in adiposity, we did not find evidence for upregulation of genes involved in fatty acid oxidation based on QPCR of abdominal adipose tissue. In conclusion, these studies demonstrate that dietary enrichment in ALA reduces adiposity, but the mechanisms remain to be determined.