Some big news on the fish-oil front came out this week. News sources cite a British Medical Journal article about the effects of fish oil supplements on heart health; here’s the researchers’ conclusion:
Regular use of fish oil supplements might be a risk factor for atrial fibrillation and stroke among the general population but could be beneficial for progression of cardiovascular disease from atrial fibrillation to major adverse cardiovascular events, and from atrial fibrillation to death.
They’re saying that fish oil supplements may be good for those with existing heart disease, but bad for those without heart disease. Do they know why? No. They added a “further studies are needed” clause at the end.
An important thing to know here is that this study examined a large health database (the UK Biobank study) of 415K persons that collects individual health information over time. The researchers could identify some patterns, but not causal links, using this type of investigation.
But what could explain this strange pattern? Two things: 1) the difficulty of finding meaningful correlations amidst a lot of noise in big data sets; and 2) the extreme difficulty of separating out the contributions of a single nutritional element to one’s overall health over time.
I’m particularly interested in 2). I’m posted time and time and time again about a similar controversy over eggs.
As if this weren’t enough to swallow, another strange fish-oil result also came out this week. In a meta-analysis of 28 studies, some other fish-oil researchers found evidence to suggest that omega-3 supplements modestly reduce aggression in children and adults. They found this effect across various types of aggression.
Huh, you may be thinking. Me, too. My response to all of this is that nutritional research is really hard to do, for the obvious reason that science just doesn’t have the methods to precisely track the effects a single element (like a fish oil supplement) has in the context of whole diets over time and in various environments, combined with other health-related behaviors. They’re trying, noticing trends, and pursuing lines of investigation.
But time and time and time again, what we see at the end of these sorts of articles (both popular and academic) is something like “it’s better to get these nutritional elements in food rather than supplement form”. Why? Because nutritional supplements are largely unregulated (at least in the US), so you really don’t know what you’re getting. That’s enough to give me pause.
Fun fact: Nutritional supplements are a big business worldwide: the industry was valued at $177.5 Billion in 2023, and is growing. According to one study, around 7% of adults in the US take fish oil, the most common omega-3 fatty acid supplement.
Another fun fact: you can get omega-3 fatty acids from non-meat sources: flaxseed, flaxseed oil, walnuts, canola oil and chia seeds provide more concentrated forms of omega-3s.
I’m not in a position to give out medical advice, nor would I if I were. But for what it’s worth, the nutritional supplements business definitely seems fishy to me.
