The Selenium Health Benefit

The Selenium Health Benefit

Producer Potts  0:10  

There has been so much fear around eating seafood due to Mercury. I did hear you recently talk about some new studies around the Selenium health benefit. Can you explain what that is and share why this is a fear we can finally all let go? 

Dr. Sarah  0:39  

I would love to, this is one of those myths that just keeps, keeps going. And really we need to, we need to just move on. We need to understand that science has given us answers and and we can, we can eat our seafood in peace, at least mostly so it helps to explain, first, what Mercury does in our bodies and why it is like a legitimate, harmful element to be exposed to. So the form of mercury that we worry about is called methylmercury. So that is an organic form of mercury. It’s produced by bacteria when they encounter elemental mercury, or like non organic mercury, in their environment, and then methylmercury, like bioaccumulates up the ecosystem I got the food chain in, especially aquatic ecosystems. That’s why we see methylmercury accumulation, especially in large predators like swordfish and pilot whales and mako sharks. So methylmercury the way that it harms us if we’re exposed to it is that it binds irreversibly to selenium. Now we have 25 to 30 different enzymes in our body that are called seleno Enzymes because they have one or more selenium molecules as part of their molecular structure. So it’s part of how those enzymes actually do their job. And a bunch of these seleno Enzymes hang out. They live in our brains, and what they do in our brains is protect our brains from oxidative damage. So they’re really, really important. We’re like, exposed to oxidants, so like molecules that have an oxygen in them, that are highly reactive and can do things like damage proteins and damage DNA. We are exposed to these at all times, and we have a bunch of different antioxidant defenses in our bodies. And seleno Enzymes are particularly important antioxidant enzymes in our brains. So the way, like mercury poisoning affects us is by we get exposed to the mercury, it binds to the Selenium in our seleno enzymes, and then those seleno Enzymes can’t do their job of protecting the brain from oxidative damage, so that damage builds up over time, and that leads to all of the neurological symptoms that are seen with mercury poisoning. And that’s where the term mad as a hatter comes from. So in ye oldy days, hatters used mercury in felt making. So they were exposed to inorganic mercury. So the kind of mercury that has a harder time getting into our bodies and a harder time binding with our Selena proteins. But they were exposed to tons and tons and tons of it. Like, there’s nobody nowadays who’s exposed to, like, that high level of mercury. It was back when it was, like a really cool, you know, like shiny liquid in a bottle that would have these really weird beating-like properties like my uncles used to just play with mercury in the basement, because it was, again, the old days. Oh, goodness. So that explains what? No, I’m not gonna say that. So, so, yeah, so, like, before we really understood the problems with mercury poisoning, Mercury was something that wasn’t like it was, it was just it was around and it was used in felt making. So felt hats. Hatters eventually would get a little bit a little bit mad, right? A little bit like they would have like clinical insanity as a result of mercury poisoning building up over years and decades, right? So, because they were being exposed to a lot of mercury, but the inorganic form, and there’s definitely been cases of mercury poisoning, lots of different case studies showing that that can happen much more quickly with methylmercury. But here’s where the Selenium health benefit value comes in. So it just so happens that, other than Brazil nuts, seafood, are the highest sources of selenium in our diets. So most fish and shellfish have 50 ish percent of the daily value of Selenium or more, up to close to 100% of the daily value selenium. So they’re great, great sources of selenium. So the methyl mercury that fish is exposed to. So mostly the fish will bind to their selenium right? It will interfere with their selenoproteins and seleno enzymes. So the good news for the fishes, though they have so much selenium that the amount of mercury that they’re typically exposed to is not enough to have them have neurological symptoms. And actually, I don’t know if methylmercury poisoning has the same symptomology in fish as it does in mammals, so actually not even sure if it would look the same. But the cool thing is that their selenium helps to protect them, and more importantly, it protects us. So for the vast majority of seafood, that fish or shellfish has way more selenium than the mercury it’s exposed to. So that mercury is mostly all already bound to selenium. So if it’s already bound, it can’t interfere with our seleno enzymes. It’s already irreversible. So it’s it’s already that chemical reaction has already happened, and the additional selenium that we’re getting from that seafood can help protect us from any mercury that might be in that fish that hasn’t actually found a Selenium molecule to bind to yet, as well as mercury exposure from other sources, right? Because it is an environmental pollutant. So there is mercury around, right? There’s some mercury in city air pollution, for example, there’s mercury in compact fluorescent bulbs. So if you break one of the compact fluorescent light bulbs, that would expose you to a little bit of mercury. So having that additional selenium is a really great thing to have in our systems. So almost all seafood have more selenium than mercury exposure, the exceptions being those, like top predators from polluted waters that I mentioned at the top of this video, swordfish. Actually, the data is mixed. So swordfish, in some studies, have higher selenium than Mercury. Some studies equal amounts, and some studies more mercury than selenium. So it seems to really depend on exactly where this word fish is fished from, and then, like Shark, whale, like really, like the really large top predator fish. So those are the ones to limit, so no more than one or two servings per week, and probably avoid for pregnant people, right? So unfortunately, fetuses are much more sensitive to Mercury, so those would be the types of fish to avoid during pregnancy, all others, like everything else common that you’re gonna get in the grocery store. Tuna has, like, 20 times more selenium than Mercury. Like it is not , even if it’s a higher Mercury fish, it’s got so much selenium that we don’t need to worry about that mercury. Salmon is a lower Mercury fish and also has way more selenium. So like, the common types of fish we’re going to get are generally all high selenium health benefit value, which is a measurement of the ratio of Selenium to mercury in that fish. And what’s really cool is, you know, when I first started talking about the Selenium health benefit value, I think in 2013 there were really only a couple of studies measuring the Selenium and mercury in fish. It is now part of biomonitoring studies done in the United States and in Canada. So it’s actually being routinely measured now. So there’s also a whole pile of different studies, because there’s just so much data, and the more data we have, the more sure we can be that eating a diet abundant in seafood is perfectly safe from a Mercury perspective.

Producer Potts  8:47  

That is so much information and it’s really good to know. So basically, a lot of these myths that we’ve heard about Mercury over the years are now we can just put it to the side, because now there’s all these new studies that have come out and really shown it’s not something we have to worry about. And again, that’s why it’s good to keep up on the science, be up to date with studies, and not be stuck in one way of thinking and being open to new information. Because if you’re someone that avoided canned tuna for so long, me because you thought it wasn’t good for you, and now you have that back as an affordable, accessible food. Yes, that’s a win. So I think that’s awesome. Where can we learn more about these common myths and the real truth about them? 

Dr. Sarah  9:37  

I have a whole chapter in my book, Nutribullet, dedicated to busting fear mongering myths about foods, all with the goal of making us feel comfortable in actual safety. What the science shows is safe or more affordable to be considered a lower quality option, but I even do like it. Nutrient breakdown to show that from a nutrition perspective, most of the time, they’re no different than the more expensive options. So chapter 10 is entirely about making us feel comfortable choosing affordable, nutrient dense foods.