Abstract
We examined the effects of fat intake and dietary fish oil on the development of obesity in mice. C57BL/6J mice were assigned to one of five groups. The first group was fed with a high-carbohydrate control diet (10% safflower oil by energy), the second group was fed with a moderate-fat diet (30% safflower oil), and the third group was fed with a high-fat diet (60% safflower oil) for 16 weeks. The other two groups were fed with fish oil instead of safflower oil as a moderate-fat diet (30% fish oil) or a high-fat diet (60% fish oil) for 16 weeks. The mice fed with the 60% by energy safflower oil diet developed marked obesity, hyperinsulinemia and hyperleptinemia, while the mice fed with the 30% safflower oil diet developed slight adiposity in the retroperitoneal adipose tissue compared to the control group. The body fat, blood leptin and insulin levels were lower in the two fish oil groups than in the 60% safflower oil group. No significant differences in blood lipids, body weight and fat were apparent between the 30% and 60% fish oil groups, and both fish oil groups showed lower blood lipid levels than the respective safflower oil groups.
These results indicate that the long-term intake of safflower oil might cause slight obesity in mice, even at a 30% by energy fat intake. Replacing all this dietary fat with fish oil effectively inhibited any body fat increase and improved the blood lipid profile in mice.
