So-called ‘omega-3’ fats found in oily fish (like salmon, trout, mackerel and herring) have a reputation for being healthy, including an ability to ward off cardiovascular diseases such as heart disease and stroke. I was interested to read a recent study which points out that while earlier studies found that supplementing individuals with omega-3 fats had broadly beneficial effects on cardiovascular disease outcomes, more recent studies have not [1].
The authors of this study then set about examining the possible reasons for this disparity. One explanation they offer up concerns the fact that omega-3 fats are most likely to be beneficial to those who have a relative deficiency in these nutrients. In recent years there have been several reports of the beneficial effects of omega-3 fats, leading increasing numbers of people to emphasise these nutrients in their diet or as supplements.
As a result, the authors suggests, individuals used in studies are less likely to be deficient in omega-3 fats, and are less likely to benefit from additional supplementation as a result.
The authors also offer another potential explanation for the more recent negative findings. This concerns a possible interaction between omega-3 fats and cholesterol-lowering statin drugs.
The authors cite studies in which omega-3 supplements were given to individuals who may also have been taking a statin. In one of these studies [2], in those taking statins, rates of complications of cardiovascular disease were 13 per cent in individuals taking omega-3 supplements compared with 15 per cent in those not taking these supplements [3].
However, in those not taking statins, the respective complications rates were 9 per cent 18 per cent. The difference in these results was not statistically significant, though this might have had something to do with factors such as small study size. Overall, the suggestion is that statins have the ability to nullify the beneficial effects of omega-3. This idea is actually put forward by the authors of the study themselves [3].
The authors of the review also go on to suggest mechanisms through which statins and omega-3 fats and statins may interact. For example, they point out that statins promote the metabolism of so-called ‘omega-6’ fats (such as arachidonic acid) which actually antagonise the effects of omega-3 fats. For example, omega-6 fats tend to be inflammatory in nature and therefore counteract the known anti-inflammatory effects of omega-3 fats (inflammation has emerged as a potent underlying driving force behind cardiovascular disease).
All drugs have potential upsides and downsides. This latest review draws our attention to yet another potential downside of statins, namely their ability to disrupt the anti-inflammatory properties of heart-healthy omega-3 fats. On the plus side, though, is the fact that statins are inherently anti-inflammatory. In fact, some believe that whatever benefits statins have has a lot to do with this property, and little to do with the impact they have on cholesterol.
When it comes to their effects on inflammation, it seems statins give with one hand but take with the other. This may help explain why, overall, they do about as much harm as good.
References:
1. de Lorgeril M, et al. Recent findings on the health effects of omega-3 fatty acids and statins, and their interactions: do statins inhibit omega-3? BMC Medicine 2013, 11:5 doi:10.1186/1741-7015-11-5
2. Kromhout D, et al. Alpha Omega Trial Group: n-3 fatty acids and cardiovascular events after myocardial infarction. N Engl J Med 2010;363:2015-2026.
3. Eussen SR, et al. Effects of n-3 fatty acids on major cardiovascular events in statin users and nonusers with a history of myocardial infarction. Eur Heart J 2012;33:1582-1588
