Krill oil: bad for heart health?

Posted on Sun, 5 Jul 15

Krill oil is often sold as a superior alternative to fish oil but studies supporting it are lacking and a new report suggests it may have adverse effects.

Marketing claims around krill oil include superior absorption and better health effects than fish oil, but, in contrast to fish oil, there is very little research on krill oil and the studies that do exist suggest it is in reality not as well absorbed (1) and may not benefit heart health at all (2,3).

One of the problems with krill oil is that because it has not been well studied, not only do we not know how effective it is; it is also hard to know just how safe it is.

Recently a group of researchers set out to study the effects of krill oil on cardiovascular health and although they expected benefits, it made things worse (4).

After 8-weeks of taking 5 g daily of Krill oil the study participants, a group of overweight men, had a significant worsening of insulin sensitivity. In addition, further analysis suggested that krill oil worsened cardiovascular risk makers (increased LDL-cholesterol and apolipoprotein B concentrations as well as carotid artery intimamedia thickness), although these effects were modest and require further confirmation.

It is unclear why krill oil was found to make insulin sensitivity worse, but the investigators propose that it may be due to proteins present in krill oil, but not fish oil, as the effect was greater after controlling for omega-3 levels. 

“We speculate that the adverse effects are more likely to be due to the krill-oil component and caution against the use of krill oil in individuals at increased risk of type 2 diabetes or cardiovascular disease,” concluded the study investigators. 

References:

1. Salem N Jr, Kuratko CN. A reexamination of krill oil bioavailability studies.  Lipids Health Dis. 2014 Aug 26;13:137.
2. Laidlaw M, Cockerline CA, Rowe WJ. A randomized clinical trial to determine the efficacy of manufacturers' recommended doses of omega-3 fatty acids from different sources in facilitating cardiovascular disease risk reduction. Lipids Health Dis. 2014 Jun 21;13:99.
3. Backes JM, Howard PA. Krill oil for cardiovascular risk prevention: is it for real? Hosp Pharm. 2014 Nov;49(10):907-12
4. Albert BB, Derraik JG, Brennan CM, Biggs JB, Garg ML, Cameron-Smith D, Hofman  PL, Cutfield WS. Supplementation with a blend of krill and salmon oil is associated with increased metabolic risk in overweight men. Am J Clin Nutr. 2015  Jul;102(1):49-57.