The anti-obesity effects of dietary trans-trans conjugated linoleic acid-rich soy oil in obese Zucker rats

Conjugated linoleic acid (CLA) is a collection of octadecadienoic fatty acids that have been shown to possess numerous health benefits. The objective of this study was to determine the effect of trans-trans CLA-rich soy oil fed as a dietary supplement on the body composition, cardiovascular and diabetes risk factors of female obese fa/fa Zucker rats. The CLA-rich soy oil used in the current study was produced by the photoisomerization of soy oil and consists of about 20% CLA, 75% of which are trans-trans isomers. This method could be used to easily increase the CLA content of all soybean oil used as a food ingredient. Rats in the treatment group were fed a diet containing 0.5% w/w trans-trans CLA isomers for a period of 100 days. The diet supplemented with trans-trans CLA-rich soy oil lowered the serum cholesterol and low density lipoprotein-cholesterol levels by 41% and 50%, respectively. Trans-trans CLA supplementation also lowered the liver lipid content significantly (P < 0.05) with a concomitant decrease in the liver weight in the obese rats. In addition, blood glucose values were improved as measured by glycated hemoglobin and an intermediary effect was observed in reducing fasting insulin levels in comparison to the control. In conclusion, trans-trans CLA-rich soy oil improves liver and serum lipid profiles, glycemia, and may reduce insulin resistance.