But there\u2019s a catch: The vast majority of clinical trials<\/a> have found that taking omega-3 supplements<\/a> offers virtually no benefit<\/a> for cognition or dementia symptoms<\/a>.<\/p>\n \u201cIt kind of intuitively makes sense\u201d that neurons need fatty acids for their health, so you should take a fatty acid supplement, said Dr. Kristine Yaffe, a professor of psychiatry, neurology and epidemiology at the University of California, San Francisco. \u201cThe problem is that most of the evidence, particularly the trial evidence, just doesn\u2019t support it at all,\u201d she said.<\/p>\n A study published last month<\/a> offers a prime example. The scientists who ran the clinical trial tried to cover all their bases: The participants were older adults who didn\u2019t eat a lot of fish (which is rich in omega-3s), suggesting they might benefit the most from a supplement. Roughly half of the participants had an increased genetic risk<\/a> for Alzheimer\u2019s, which is another group that experts think might need more omega-3s. The researchers even did lumbar punctures on some of the participants to confirm that the supplement caused omega-3 levels in the brain to go up.<\/p>\n But compared with a placebo, the supplement didn\u2019t result in any benefit when it came to people\u2019s cognition or brain structure.<\/p>\n So what\u2019s behind the disconnect? Scientists have a few hypotheses, and most are connected to diet and lifestyle.<\/p>\n Hypothesis 1: Most people already get enough omega-3s.<\/p>\n There are three main types of omega-3s that are important for health: EPA and DHA, which are primarily found in fish, and ALA, which is in nuts and seeds. The liver can convert small amounts of ALA into EPA and DHA.<\/p>\n DHA is the most vital for cognition, and there\u2019s a large reserve of it in our brains. According to Richard Bazinet, a professor of nutritional sciences at the University of Toronto, the amount of DHA our brains use every day is just a tiny fraction of that reserve.<\/p>\n Even if people don\u2019t eat a lot of fish, Dr. Bazinet thinks they still probably get enough omega-3s through their diet, particularly from ALA, to replace the small amount of DHA the brain uses.<\/p>\n \u201cWe all eat a ton of\u201d ALA, Dr. Bazinet said. And if people\u2019s DHA intake is low, the liver can convert the ALA to DHA and send it to the brain.<\/p>\n In Dr. Bazinet\u2019s mind, since virtually everyone gets enough omega-3s from their diet, the brain benefits that scientists see in people who have high blood levels of DHA are probably caused by something besides omega-3s \u2014 most likely from other healthy habits that tend to come with eating a diet rich in fish.<\/p>\n For example, when someone has fish for dinner, they typically pair it with vegetables<\/a>, not junk food. \u201cIf you\u2019re going to have a nice tuna steak, you might have a little bit of salad,\u201d Dr. Bazinet said. And \u201cwhen you\u2019re eating that meal, you\u2019re not eating something else\u201d that\u2019s less healthy for your brain<\/a>, he added.<\/p>\n Hypothesis 2: It\u2019s how you metabolize omega-3s that really matters.<\/p>\n Dr. Hussein Yassine, a professor of neurology at the University of Southern California\u2019s Keck School of Medicine, thinks it is how the brain uses omega-3s that matters most.<\/p>\n In the brain, there is a molecule that breaks down and gets rid of omega-3s. Everyone has this molecule, but Dr. Yassine has found that it is more active<\/a> in people with a genetic risk for Alzheimer\u2019s. It\u2019s possible that their brains metabolize omega-3s more quickly, depleting the levels.<\/p>\n To improve brain health, Dr. Yassine, who also led the recent omega-3 supplement trial, thinks some people<\/a> need not only to increase their omega-3 intake, but also to decrease the activity of that other molecule. Research is preliminary, but there\u2019s some evidence that this molecule is affected by the gut microbiome<\/a> and is less active in people who have a diet rich in plants, fiber and fermented foods. In other words, to benefit the brain, you need the nutrients from the tuna, as well as those from the salad or other healthy side dishes.<\/p>\n If someone has a poor diet \u201cand you just give them a supplement where the only thing you change is the level of omega-3s in their blood and in their brain, our study would suggest that it\u2019s not going to work,\u201d Dr. Yassine said.<\/p>\n Hypothesis 3: To see benefits, you need to consume large amounts of omega-3s for decades.<\/p>\n Not everyone is giving up on omega-3 supplements. Gene Bowman, an assistant professor of neurology at Harvard Medical School, thinks one reason that clinical trials tend to fail is because they only test supplements for a few years, and that may not be enough time to detect changes in the brain. When people have high blood levels of omega-3s, it\u2019s typically because they\u2019ve eaten foods rich in omega-3s \u2014 by some estimates three weekly servings of fish \u2014 for decades.<\/p>\n \u201cI think the reason for the disconnect or inconsistency, one explanation could be strictly methodological,\u201d Dr. Bowman said.<\/p>\n \u201cSo we either start much earlier and do much longer trials,\u201d he added, \u201cor we come up with a more powerful treatment that has a larger magnitude of effect.\u201d For instance, omega-3s may work best when combined with other nutrients (the fish-plus-salad theory), particularly in people who have nutritional deficiencies.<\/p>\n Regardless of the reason for why omega-3 supplements seem to fall short, the current research suggests it\u2019s a balanced diet, rather than a pill, that can help keep your brain healthy. That is also likely true for heart health<\/a>, another reason many people take an omega-3 supplement.<\/p>\n \u201cThe best evidence, as limited as it might be, is that eating foods with omega-3s seems to be a good thing and correlates with better brain outcomes,\u201d Dr. Bazinet said. \u201cBut taking the shortcut with the supplements\u201d doesn\u2019t seem to show the same benefit.<\/p>\n
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