Can This Nut Make New Neurons?

Added: 2026-05-05

[00:00:00]What if a single nut could wake up your brain? I know it sounds, well, nutty.

[00:00:06]But as a neuroscientist, let me tell you there is so much more inside this nut than [music] protein and fat. There is a special element. It can appear as a red powder, black solid, or even a gray metallic-looking form. It's number 34 on the periodic table. Do you know what it is?

[00:00:23]Selenium. Selenium is central to our biology. It's the nucleus of a whole class of essential proteins known as seleno proteins that can serve as antioxidants and even wake up stem cells from hibernation in the brain. And today, we're [music] not just cracking nuts, we're cracking into the cranium to see what selenium can do in the brain.

[00:00:43]We'll tie together a beautiful biological choreography of diet, exercise, and brain health. And by the end of this video, I promise you'll never see this nut the same again.

[00:00:55]Let's go. Activate sleeping stem cells in the brain's memory center. One underappreciated mechanism I never hear anybody talk about is nothing beats the Brazil nut. Led to a 55% net increase in overall neurogenesis.

[00:01:10]It's pretty amazing. Stem cells don't just disappear with age. It sounds like a tricky problem, right?

[00:01:16]First, here's a quick road map to this video. We're going to start by covering fascinating data on how exercise and selenium enhance neurogenesis, the birth of new neurons in the brain. Then, in chapter two, we're going to dive to human randomized control trial data on Brazil nut supplementation and cognitive function. And finally, in chapter three, we're going to round all this out with a high-yield rapid-fire breakdown of supplements that support brain health, including those I use in my own supplement stack. And as always, if you want deeper insights, full references, and bonus nuance, including a whole page devoted to Alzheimer's prevention, head over to statecuriousmetabolism.com.

[00:01:55]But with that, let's get right into chapter one. Exercise and selenium together enhance neurogenesis. Here's something that I bet you don't know about exercise. Exercise sends signals to the brain that can help with learning and memory. Okay, maybe you did know that, but we'll get to things you don't know. In part, exercise activates sleeping stem cells in the brain's memory center, the hippocampal This is a region not only crucial for memory, but also vulnerable in dementia, particularly Alzheimer's disease. Now, while there are many mechanisms by which exercise can improve brain function, one underappreciated mechanism I never hear anybody talk about is selenium. As I introduced, selenium is critical for building a whole class of antioxidant proteins known as seleno proteins. There are literally dozens, and they perform critical functions, particularly in the brain.

[00:02:43]And fascinatingly, one thing exercise does is it increases levels of a critical selenium transporter called selenoprotein P1 or SEPP1 that gets selenium into the brain, where it's needed to generate antioxidant enzymes with neuroprotective properties. Well, let me not just take you with the vagaries. Let's get into the first of our studies. A fascinating study published in Cell Metabolism informed selenium mediates exercise-induced adult neurogenesis and reverses learning deficits induced by hippocampal injury and aging. I know it's a mouthful, but if you actually read the title, it tells you exactly what the study is about. Now, to get into it, in one experiment, researchers had mice run for 4 days on a running wheel and compared them to sedentary control mice, lazy couch potato mice.

[00:03:30]The researchers then performed a broad screen to see what proteins were increased by exercise. And one protein shot up like Hermione's hand in class.

[00:03:39]It was the selenium transporter, the SEPP1, which you can see here in purple.

[00:03:44]This already provides a clear biological basis for how exercise can get selenium into the brain.

[00:03:49]Therefore, we next want to ask or find out what would happen if we treated the brain with selenium, specifically targeting neurons in these key memory centers, like neurons in the hippocampus.

[00:04:03]But here's a problem. How do you track the growth of new neurons in a living brain? It sounds like a tricky problem, right? Here's what they did. They infused selenium into the brain and tracked newly generated neurons using a dual stain, two stains, CLDU and NeuN.

[00:04:19]Here's how it works. CLDU incorporates into dividing cells, into their DNA as they're dividing, and NeuN labels neurons. So, when you overlap these, you get a signal from the neuron saying, "Hey, I'm a new neuron." And that's how they solved the problem of new neuron tracking. Therefore, they could track the birth and survival of new neurons.

[00:04:39]And they found that selenium treatment massively increased adult neurogenesis, new neurons in the brain. In fact, selenium treatment led to a 55% net increase in overall neurogenesis.

[00:04:51]That's pretty amazing. The next problem to solve, the next question to ask is, well, how exactly does this work? And if I'm being dead honest with you, there's not a single clear cut answer.

[00:05:00]Generally, that's the rule in biology.

[00:05:02]Things don't work super linearly.

[00:05:04]There's not just one thread, it's more of a web. But given seleno proteins' role as antioxidants in the brain, one factor you might want to look at is oxidative stress. You might expect selenium to decrease oxidative stress in the brain. And this is important since oxidative stress tends to lead to the death of neurons. A key pathological feature of neurodegenerative diseases and dementia is oxidative stress. So, at a basic level, it makes sense that increasing selenium would increase seleno proteins and reduce oxidative stress. Are you following?

[00:05:33]This is exactly what was seen. But that's not the whole picture. There are also direct effects of selenium on neuron stem cell programming. So, contrary to popular belief, stem cells don't just disappear with age. Rather, they mostly go quiet in the brain. Enter kind of a sleepy mode, a quiescence. And they can be very difficult to wake up.

[00:05:56]But seleno proteins appear to do just that. They wake neuronal stem cells up out of their hibernation, leading to the generation of these new healthy neurons.

[00:06:06]So, now we see the graphic I showed you earlier, but with more details fleshed out. Here's a fuller picture. Exercise increases the selenium transporter in the brain. The selenium transporter SEPP1 transports selenium into the brain. The brain then turns selenium into the seleno proteins. The seleno proteins reduce reactive oxygen species, oxidative stress, and wake up neuronal stem cells, leading to neurogenesis.

[00:06:32]But biomarkers and mechanisms are one thing. What about actual learning and memory? Well, here's the problem. As animals age, be you a mouse animal or a human animal, in this case we're the same, there tends to be a decrease in selenium levels and increase in oxidative stress.

[00:06:50]Furthermore, in people, it has been observed that blood levels of selenium correlate inversely with the probability of cognitive decline. So, if you're following, if we assume some element of causality, we see a cascade emerge. Age leads to selenium dropping, leads to increased oxidative stress, and decreased neurogenesis. This increases risk of cognitive decline.

[00:07:13]Now, if selenium were truly causal in cognitive decline, you might expect supplementing with dietary selenium would improve learning and memory in older animals, be you a mouse or a human. So, therefore, we, now we part of the research team on a quest, set out to do our next experiment. Let's give dietary supplementation at low concentrations, just 10 parts per million, to old mice. What happened?

[00:07:37]Selenium-supplemented old mice had significantly more neurogenesis, proliferating new neurons, in the memory region of the brain. Here, you can see the blue stain. The blue stain also reveals proliferation of new cells in living old mice. Clearly, as marked by the increase in the blue stain, there's more neurogenesis in the brains of these selenium-supplemented mice. What's more, selenium supplementation improved performance on learning and memory tasks as well. For example, in one task known as the active place avoidance task, it's a little bit of a mean task, but it is a good task, mice are placed on a rotating platform and tested for their ability to learn to avoid a stationary shock zone, shown here in gray, using visual cues placed around the platform as references. And what they found was that selenium-supplemented mice were significantly better than control mice at avoiding getting a shock.

[00:08:28]So, piecing this all together, let's go over what we've learned so far on a high level.

[00:08:33]Lower selenium levels are associated with cognitive impairment in animals and in humans. Exercise improves learning and memory across species.

[00:08:42]One way it works, one way exercise works, is by increasing the transport of selenium into the brain. Once in the brain, selenium supports antioxidant defenses and enhances neurogenesis, the birth of new neurons. Selenium supplementation, dietary selenium supplementation in older animals, boosts both neurogenesis and cognitive performance, learning and memory. So, taken together, this paints a compelling picture. One we'd like to believe, right? And one that could easily translate into action. If we want to support neurogenesis, learning and memory, we should exercise, of course, and maybe combine that with selenium-rich food. And when it comes to selenium-rich foods, nothing beats the Brazil nut. Not even close, which is why it's been featuring throughout this video. Hopefully, you got that. A single Brazil nut can contain as much as 90 micrograms of selenium, which is well above the recommended daily allowance of 55 micrograms for adults. So, yes, just one singular Brazil nut will give you your entire daily value of selenium.

[00:09:45]Now, here's where the rubber hits the road. It might seem a little optimistic to suggest that eating just a single nut could improve learning and memory, cuz that's the hypothesis what to, right?

[00:09:56]So, therefore, let's ask that question.

[00:09:59]Can a selenium-rich diet, maybe just a Brazil nut, improve learning and memory in humans? And that brings us to chapter two.

[00:10:07]A human randomized controlled trial on Brazil nut supplementation and cognitive function. So, in 2015, researchers in Brazil, ironic, right? Published a randomized controlled trial involving 20 participants with mild cognitive impairment. Average age was 78, and they completed a full 6-month study.

[00:10:27]The intervention was pretty simple. The treatment group consumed one one Brazil nut per day.

[00:10:34]And the results?

[00:10:36]Blood levels of selenium in the treatment group rose dramatically from 56 to 291 micrograms per liter with no change in the control group. This increase in selenium in the blood was accompanied by a rise in antioxidant activity, specifically something called glutathione peroxidase. You don't need to know that. It's a key antioxidant enzyme. So, selenium levels and antioxidant capacity improved with Brazil nut supplementation.

[00:11:02]But what about cognition? Amazingly, participants in the treatment group, remember, a Brazil nut per day, showed statistically significant improvements in two cognitive measures, a verbal fluency test and a test of something known as constructional praxis, which is a measure of visual-spatial and executive function. So, here we have a randomized controlled trial, human data suggesting that increasing dietary selenium can improve cognitive function in just 6 months.

[00:11:31]How cool is that? And that brings us to chapter three, high-yield rapid-fire breakdown of brain health supplements, those that I use. This is sort of a pivot. I just want to give you a broader, flushed-out idea of how to support your brain today with high-yield tips. So, first, fatty fish. This contains selenium and omega-3s. So, staying on the selenium theme for a moment, it's worth noting that in addition to Brazil nuts, fish, like sardines and halibut, are amazing sources of selenium. Just 3 oz of halibut can deliver up to 90 micrograms of selenium, like a Brazil nut. And as an added benefit to fish, fish contains selenium that is often bound to amino acids, like selenomethionine. Methionine is an amino acid, and this makes it more bioavailable to your body, so you can absorb it and use it more efficiently.

[00:12:20]The research on fish is pretty clear.

[00:12:22]More fish intake, especially fatty fish, is associated with better memory and cognitive performance as we age. This is likely due to a combination of neuroprotective forms of selenium in the fish and the presence of the long-chain omega-3 fatty acid DHA, which is the most important nutrient for the brain.

[00:12:39]I suggest, personally, eating fatty fish at least twice per week for your average person. Focusing on options like sardines and Alaskan sockeye salmon, both of which are low in mercury and incredibly nutrient-dense.

[00:12:51]Now, for most people, regularly eating fatty fish will be enough. But if you do want to go above and beyond, especially if you have genetic risk factors like I do, I have two copies of the APOE4 risk gene for Alzheimer's, it may be worth considering targeted supplementation.

[00:13:06]That's why I personally take a special form of DHA called lysophosphatidylcholine DHA. If you've been following me for a while, you've definitely heard me talk about this, but this is a form that has privileged access to the brain and is more efficient at raising brain DHA levels than conventional fish oil. I reviewed the data on lysophosphatidylcholine DHA a lot before, so I won't go into it. You can see this previous content for more, but the product I personally use and intend to take for many years to come is called X Centrate Omega Max. It contains a patented form of lysophosphatidylcholine DHA. Now, warning, admittedly, it is not cheap, but for me and for my parents, it's a worthwhile investment. So, if you want to try it, you can use the discount code I have for you, stay curious for 20% off. No pressure, it's just something I genuinely use and a product that I believe in. But next up on our roster for brain protection, we're moving 31 positions up the periodic table from selenium to lithium.

[00:14:01]Lithium is a deceptively simple element, but it plays a powerful and underappreciated role in brain health.

[00:14:07]For decades, researchers have observed an association between higher trace lithium intake, particularly in drinking water, and lower incidence of Alzheimer's disease. Combine that with a strong biological rationale for how lithium can protect the brain. What lithium does is it inhibits a protein in the brain called GSK3 beta.

[00:14:25]This protein, which doesn't have a very creative name, but it's very important in brain health, is involved in many processes in Alzheimer's disease, including perpetuating amyloid plaque production and phosphorylated tau neurofibrillary tangles, as well as causing brain insulin resistance. And interestingly, when you examine human brains, lithium levels are reduced in the brains of patients with cognitive impairment and Alzheimer's disease. But there's more. Even more intriguing, lithium appears to be sequestered within plaques, amyloid plaques in the brain, potentially trapping it away from where it's needed. And if you're paying attention and think about it, this sets up a vicious cycle. Lower lithium means you're not inhibiting GSK3 beta, so that's more active, which means more amyloid and tau pathology. There's more amyloid and tau pathology, it's trapping more lithium, which means even lower lithium, and the vicious cycle continues.

[00:15:15]What's more, I know there's a lot more to this. In a major study published out of Harvard last year, researchers showed that lithium deficiency can cause Alzheimer's-like pathology in animal model, and that supplementing with a specific form of lithium, lithium orotate, at very low doses, just microdosing, could reverse these Alzheimer's pathologies. I dive into these findings in more details in this video, but the overall body of evidence has led me, personally, to supplement with 5 mg of lithium orotate daily. The brand I use is Pure Encapsulations. It's a well-established and reputable company. I have no affiliations or sponsorships, it's just the brand I trust myself.

[00:15:51]Finally, rounding out our high-yield hit list is nicotinamide adenine dinucleotide, or NAD. NAD is a critical energy-carrying molecule in the brain, sitting at the nexus, at the center of nearly every major metabolic process, glycolysis, beta-oxidation, oxidative phosphorylation, the Krebs cycle, and more.

[00:16:09]Without NAD, there is no life. And what's very interesting is that in Alzheimer's disease, there is a deficiency of NAD, or to frame it more constructively, NAD is a resilience factor in the aging brain.

[00:16:23]Now, while NAD levels naturally decline with age, studies show that when NAD levels remain elevated in age, cognitive function is preserved even in brains with a lot of amyloid pathology. In other words, high NAD might buffer against neurodegenerative changes. And the great news here is NAD levels can be boosted regardless of age. Proven strategies include aerobic and resistance training, building up muscle, improving VO2 max, ketogenic diets and fasting, and for those exploring supplementation, you can take NAD precursors. In particular, NMN, which stands for nicotinamide mononucleotide, or NR, nicotinamide riboside. Human controlled trials have shown that supplementing with just 1 g daily of either of these NAD precursors can double NAD levels in as little as 2 weeks. For a deeper dive into those studies and practical recommendations, you can see this content.

[00:17:16]But now, let's bring this full picture.

[00:17:18]We started with the humble Brazil nut, but inside this simple snack, selenium, a trace element with powerful effects on the brain. From neurogenesis to antioxidant defenses, the data are clear, selenium matters. And it's just one part of a bigger picture. Today, we looked at four key players in brain health, selenium, DHA, lithium, and NAD.

[00:17:40]Each has strong science behind it, and I encourage you to go down the rabbit hole on each of these. And together, they tell a story.

[00:17:46]Your habits, how you move, eat, and supplement shape your cognitive future.

[00:17:51]Now, if you want deeper dives, full references, curated protocols, head to stay curious metabolism.com. And thanks for watching, and as always, thanks for staying curious.