Krill Oil vs. Fish Oil: Animal Study Looks at Weight and Lipid Genes

This study used rats fed a high-fat diet to compare krill oil and fish oil supplementation and see how each affected weight gain, blood sugar, hormones, and fat-related gene activity in the liver. Rats were split into four groups: a normal diet, a high-fat diet alone, or a high-fat diet plus either fish oil or krill oil for eight weeks.

All the high-fat diet groups gained significantly more weight than the normal-diet group, but there was no meaningful difference in weight gain between the fish oil and krill oil groups. Both omega-3 sources changed blood lipid levels somewhat, but neither meaningfully improved blood sugar regulation or the hunger-related hormones ghrelin and leptin compared to the untreated high-fat diet group.

At the genetic level, the two oils behaved differently. The krill oil group showed slightly higher liver activity of enzymes that process omega-3 fats and slightly lower total liver fat, though these differences were not statistically significant. Genes involved in fat metabolism (FADS1 and FADS2) were activated differently depending on which oil the rats received, suggesting the two sources may work through somewhat different biological pathways.