The body composition and lipid metabolic effects of long-term ethanol feeding during a high ω6 polyunsaturated fatty acid diet in micropigs

Abstract

Our previous research with miniature pigs has shown that long-term ethanol feeding with a low-fat diet decreases arachidonic acid (20:4ω6) levels in multiple tissues, but we did not find significant liver pathology. In this study, we investigated the effect of ethanol feeding with high dietary linoleic acid (18:2ω6) on tissue fatty acid (FA) profiles and body composition. Five Yucatan micropigs were fed 370 kJ (89 kcal)/kg body weight of a diet containing ethanol and fat as 40% and 34% of energy, respectively; five control pigs were pair-fed corn starch in place of ethanol. Corn oil, 61% 18:2ω6, supplied most of the dietary fat. Liver biopsies were performed at baseline (n = 2 per group) and at three other time points (n = 5 per group). Phospholipid (PL) FA levels were measured by thin-layer and gas chromatography. Body composition was analyzed by underwater weighing of carcasses. Body composition analysis demonstrated a marked reduction of carcass fat in the ethanol group, but no significant reduction of carcass lean weight after 12 months. In liver PLs, the ethanol group showed decreased 20:4ω6 and docosahexaenoic acid (22:6ω3) after 1 month. While the decreased 20:4ω6 remained constant after 1 month, 22:6ω3 showed a progressive decrease up to 12 months, resulting in a continuous decrease of the ω3 ω6 FA ratio. This slowly progressive decrease in the ω3 ω6 ratio in liver PLs with ethanol feeding may have enhanced the inflammatory response in the liver, contributing to liver pathology. Body composition results indicate marked wasting of energy in the ethanol group.