LECCE, Italy—Krill oil inhibited liver fat production and reduced levels of triglycerides and cholesterol more than fish oil in a recent Italian study (J Anim Physiol Anim Nutr. 2011 Feb 25. DOI: 10.1111/j.1439-0396.2011.01135.x). Rats fed a diet enriched with krill oil experienced more pronounced inhibition of hepatic lipogenesis than rats fed fish oil, at least at short feeding times, and the researchers said the krill oil-fed rats had lower levels of hepatic triglycerides and cholesterol comparison to fish oil-fed rats.
The animals were treated for 6 weeks with diets containing 2.5-percent krill oil or 2.5-percent fish oil, or a control diet without supplementation of omega-3 fatty acids. The activity of three key enzymes in the liver involved in the metabolism of fat was investigated together with blood and liver levels. The study revealed beneficial effects of both omega-3 supplements. The inhibition of the three enzymes was significant with krill oil and fish oil, but the response to krill oil treatment was more pronounced, especially at shorter feeding periods (two to three weeks). The study also revealed fat-lowering effects from the omega-3 supplements and confirmed previous findings that krill oil is effective in reducing liver triglyceride and cholesterol levels. Krill oil reduced liver triglycerides by 20 percent, compared to 10 percent in the fish oil group, whereas the cholesterol levels decreased by 33 percent (krill oil) and 21 percent (fish oil).
The enzymes investigated included mitochondrial tricarboxylate, cytosolic acetyl-CoA carboxylase and other lipogenic enzymes. The researchers found a time-dependent decrease in the activities of the mitochondrial tricarboxylate carrier and of the lipogenic enzymes was in mice fed krill oil. This was due to a reduced expression of the protein. The mitochondrial tricarboxylate carrier supplies cytosol with the carbon units necessary for hepatic lipogenesis. The activities of cytosolic acetyl-CoA carboxylase and fatty acid synthetase are therefore strictly connected to the function of mitochondrial tricarboxylate carrier.
"These studies confirm the beneficial effects of krill oil on liver lipid levels that we have previously seen in two different animal models of obesity,” said Kjetil Berge, Ph.D., R&D director at Aker BioMarine, Oslo, Norway. “Moreover, the study elucidated the mechanism behind the beneficial effects of omega-3 supplementation, by demonstrating regulation of lipid synthesizing enzymes. This study gives us a foundation to study cellular mitochondrial processes in more detail in future studies."