In this video, the presenter shares his personal habit of eating fish daily and examines two recent nutrition studies to assess the benefits and risks of frequent fish consumption. The first study, a cross‑sectional analysis of 3,123 older adults from NHANES 2011‑2014, found a dose‑response relationship between higher fish intake and better cognitive performance across memory and executive function domains, even after adjusting for lead, cadmium, methylmercury, and selenium exposure. The authors highlighted the importance of the selenium‑to‑mercury ratio, noting that many fish (e.g., yellowfin tuna, mahi‑mahi) have high ratios that may mitigate mercury toxicity. Practical advice includes avoiding high‑mercury species (shark, swordfish), especially for pregnant individuals, and using broken‑cell‑wall chlorella or cilantro as potential chelators. The second study, a meta‑analysis of >160,000 UK Biobank participants, linked higher circulating DHA (and a higher omega‑3 index) to a 17% lower risk of all‑cause mortality, 21% lower cardiovascular mortality, and 17% lower cancer mortality over a median 14‑year follow‑up. The paper offered biological plausibility via telomere preservation and protection against sarcopenia. The presenter discusses nuances such as self‑reported dietary data, healthy‑user bias, the role of DHA transporters (MSFD2A) and lysodHA forms (e.g., krill oil), and the limitations of using the omega‑3 index as a brain‑specific biomarker. He also provides vegetarian alternatives (algae oil for DHA, Brazil nuts for selenium) and shares a personal macadamia‑Brazil‑nut butter recipe, noting an affiliate relationship with a macadamia brand. Throughout, he balances enthusiasm for daily fish with cautionary guidance, aiming to equip viewers with evidence‑based tips to decide their own optimal fish intake.
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I eat fish daily, like every single day. From the convenience of having tinned sardines in the hospital as a snack, which is way better than hospital Domino's pizza, to the amazing flavor of fatty New Zealand ora salmon with crispy skin on a cast iron, to a snack of smoked salmon with buffalo mozzarella and a drizzle of olive oil, like, chef's kiss. I really love fish. But eating fish daily potentially has some risks. Exposure to certain organic pollutants and high levels of heavy metals like methylmercury. So in this video, what I'm gonna do is break down some new research about the concerns with respect heavy metals in fish and the relationship between fish and all-cause mortality, cancer-related mortality, cardiovascular-related mortality. And by the end of this video, you're going to understand some nuances that I bet other people don't and walk away with some useful tips. And then you can decide whether or not you want to eat fish every single day like me, or you want to moderate your intake. But no matter what, I promise you're going to learn something. Welcome to my channel, stay curious. The first paper paper we're going to look at is a brand new paper published in a premier nutrition journal, the American Journal of Clinical Nutrition. It's entitled Fish Consumption and Omega-3 Polyunsaturated Fatty Acids from Diet Are Positively Associated with Cognitive Function in Older Adults, Even in the Presence of Exposure to Lead, Cadmium, Selenium, and Methylmercury: A Cross-Sectional Study Using NHANES 2011-2014 Data. This was an assessment of 3,123 adults over age 60. They assessed fish intake using a survey of intake over the last month, and then measured levels of lead, cadmium, methylmercury, and selenium, and assessed 3 domains of cognition: immediate recall, delayed recall, and executive function. And I'll get to the punchline straight away, which was that across the population, higher fish intake associated with better cognitive scores across all domains. So you see that very clearly here on the x-axis is fish intake. As you go to the right, you have more fish intake and higher scores are better. So you see across all 3 rows, all all 3 cognitive domains. First, focusing on the left column, the black line, there is an increase in cognitive function with increased fish intake. That's the left column. Now the middle column is breaking it up, stratifying by age. So the green line is the younger older adults, and then the middle line is a little bit older, and then the purple line is even older. So there's still an age effect. And then the far right is stratified by sex, where the green line is females and the purple line is males, because yeah, we're lower, we're stupider. But bottom line, independent of age and sex, there was a dose-response relationship. More fish intake associated with higher cognitive scores. But there's an added layer here, which you may have picked up on from the title, which is they wanted to assess, you know, what is the balance of factors? Because more fish, you get more omega-3s, which are good for the brain, but you also may get exposed to heavy metals, and that could be bad. So what was original about this study was they kind of looked at those balance of factors and found actually, even accounting for exposures to lead and cadmium, methylmercury, fish intake associated with higher cognitive scores. The fish intake balanced out exposures to heavy metals, and there was an added layer here whereby selenium, a micronutrient selenium, had an added positive effect that maybe synergized with the omega-3. They reference some other studies looking at the selenium to mercury ratio in various fish and show things like yellowfin tuna have a super high selenium to mercury ratio of 14.1, and mahi-mahi also very high selenium to mercury ratio at 13.1, as compared to something like a mako shark at 0.5, much lower. So again, another consideration, something I didn't think about— selenium to mercury ratio, not just absolute levels of mercury, which I thought was pretty cool. Now, all that aside, I do want to emphasize one should not be eating very high mercury fish so often. Definitely don't eat swordfish or shark every day, especially for people with certain medical conditions and pregnancy. You don't want to have high mercury fish during pregnancy. I still want to throw that caveat out there. And one other additional tip, trick, practical tool, some people swear by broken cell wall chlorella or even cilantro as a chelating agent that may be able to bind up. I've actually played with this myself and was able to reduce mercury levels by including a homemade broken cell wall chlorella cilantro mayo. I like making my own homemade mayo, and I added some broken cell wall chlorella and cilantro to it and was eating with all my fish, and my mercury levels dropped from 11 to 7, which is actually a pretty substantial drop, although my mercury levels weren't that high to begin with. So anyway, I thought this was a really interesting study. The takeaway is more fish intake tends to be better, at least up to, in this study, 6 servings per month, which isn't all that high, to be honest. But nevertheless, more fish intake tends to be better, and we can consider the selenium to mercury ratio as well, which I think is a pretty interesting perspective. Now, moving Moving on to study 2. So the second paper we're going to look at is another new 2024 paper entitled Circulating Docosahexaenoic— try saying that 5 times fast— docosahexaenoic, docosahexaenoic, docosahexaenoic, docosahexaenoic, docosahexaenoic. No wonder they just say DHA. Circulating Docosahexaenoic Acid and Risk of All-Cause and Cause-Specific Mortality. Now, what they did in this study is they wanted to assess associations between DHA levels and long-term all-cause mortality and cardiovascular and cancer-related mortality. So what they did is they analyzed UK Biobank and FORCE meta-analysis data including 1,000— not 1,000, 160,000, over 160,000 subjects with a median follow-up period of 14 years. And after a multivariable adjustment, they found a 17% lower risk of all-cause mortality, death from any cause, 21% lower risk from cardiovascular disease-related mortality, and 17% lower risk for cancer-related mortality. So a really big effect size. In addition to the large effect sizes, they provide biological plausibility for why this may be the case. Here are two examples. They point out blood EPA and DHA levels strongly predict the rate of telomere shortening. Telomeres are the caps on the end of your chromosomes that shorten as we age, and they're a biomarker of aging. And they also say that these fatty acids, EPA and DHA, have been shown to lengthen telomeres in some human studies. So that's one element of biological plausibility. Also, long-chain omega fatty acids can protect against age-related muscle loss, sarcopenia, and lean mass as we age is, is an important predictor of longevity. So in addition to the large effect sizes, they provide some biological plausibility, which is quite important. Now, another element I want to add is what were the actual levels in participants? They looked at DHA levels, DHA range, and also another associated marker, omega-3 index, which I'm going to focus on because it correlates with DHA levels and more people have actually measured this. So the omega-3 index is the percent of long-chain fatty acids, long-chain omega-3s, Omega fatty acids in cell membranes, in particular measured in red blood cell membranes. So an optimal level is around 12, at least that's what most indices say. Now if you look at the data, they break up participants into quintiles, so groups of 5, where the highest quintile threshold was a level of 8.72, which is still a little bit suboptimal. So one has to wonder, what would the effect on longevity be in people with optimal levels at 12, or people in super optimal levels, something that is like near dolphin level or Nick level? I actually have my levels tested and I'm at 17. 2, so ridiculously high. Will this translate into even greater longevity? I don't know. I'll let you know on my 150th birthday, if you're still around. I think I will be. So those are the studies I wanted to go over. They do come with limitations and caveats. One is that for Study 1, there was self-reported fish intake. However, it was concordant with blood omega levels, so I think it was probably a reliable marker of intake. There's also the element of healthy user bias. Even if you try to adjust for variables associated with dietary quality. People who eat more fish probably are just gonna be overall eating a healthier diet. So that's a confounding variable. That said, I do think the effect size, particularly in study 2, is pretty compelling for me, but there is an element of healthy user bias that I want to claim. Another nuance here is that just because you say eat fish and get DHA into your blood doesn't immediately translate to that going into the brain. It doesn't go through the brain blood-brain barrier via like a passive diffusion. There is a transporter entitled MSFD2A, that can be activated in certain forms of DHA, get transported into the brain more easily, like lysodHA, which is conjugated to a molecule that allows for easier transport. And things like krill oil are very high in lysodHA. So you might get more bang for your buck with certain forms of omega-3 if you supplement them. So if you supplement, maybe use krill oil. There are some studies showing that that might be beneficial. And there are also questions about what is the best biomarker for omega-3 presence in the brain. And it might be something other than, say, an omega-3 index. It may be brain-derived neurotrophic factor levels, BDNF levels. So those are all some caveats. That said, I do still find these two studies very interesting and I wanted to communicate them to you. I hope you found them interesting as well. Now for vegetarians, I just do want to throw out there, you can still get DHA on a vegetarian or vegan diet, including DHA from algae oil, and also get selenium. You can't just get selenium from fish. I mean, so you can just get selenium from fish, but you can also get it from other sources. Probably the richest source is Brazil nuts. A single Brazil nut has, I think, 96 micrograms of selenium, which is like 2 times the RDA recommended level. So like 1 Brazil nut and you got your selenium from the day. Me personally, I really like Brazil nuts. I actually put them on— this is a recipe from my friend Martina Slaryova— I blend 2 cups of macadamia nuts with 10 Brazil nuts, 1/4 teaspoon of vanilla powder, and 1/4 teaspoon of sea salt, and it makes this incredible selenium-supplemented natural macadamia butter that I just absolutely love. And I'll just even put it on fish because because basically I'll eat it on anything. I love macadamia nuts, hence the t-shirt. This is limited edition, you can't buy it. They accidentally printed it when I wasn't actually supposed to have it, so now it's just my shirt. Mine. You can't buy it. But you can buy macadamia nuts if you enjoy them. That's totally your call, but I'll put links to buy those below because, as I've mentioned before, I am a partner of Hass Macadamia. I have been purchasing their product for many years and I absolutely love macadamia nuts, fish aside. If you want to know something about my diet, I eat a lot of fish, macadamia nuts, and olive oil. All that said, I hope you have a wonderful day. I hope you learned something. And as always, I love interacting you in the comments, so please leave a comment.
