Ok I used AI to Make sense of all the links and papers, and the results basically claim the opposite than what he says… Here a rundown summary using all the Research studies (just as as sidenote, ofc you can make your own conclusions up by piling up a bunch of questionable studies to proof your claims, so its important to look at who made these studies, and how reliable they actually are. I’m just not enough of an expert in that field to make a proper judgement out of that, hence I’m asking here in the hope to get some feedback from the huel team):
Two Types of Selenium in Food: What the Research Actually Shows
I’ve been diving deep into the research on selenium types in food, and the findings are fascinating—and concerning. While I couldn’t access the specific YouTube video you mentioned, I did a comprehensive review of the peer-reviewed scientific literature on this topic. Here’s what the actual research shows.
The Two Main Types
There are essentially two categories of selenium found in food and supplements:
Organic Selenium Forms:
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Selenomethionine (SeMet) - primary form in plants, grains, Brazil nuts
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Selenocysteine (Sec) - primary form in animal products, the “21st amino acid”
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Se-methylselenocysteine (MeSeCys) - found in garlic, onions, broccoli
Inorganic Selenium Forms:
Bioavailability and Toxicity: The Paradox
Here’s where it gets interesting. A study in Metallomics found an inverse relationship between bioavailability and toxicity. Organic selenium forms showed 2.5-fold higher bioavailability than inorganic selenite, yet were dramatically less toxic:
Despite accumulating more selenium in tissues, the organic forms caused far less harm. The researchers concluded that inorganic selenite generates reactive oxygen species during metabolism, explaining its higher toxicity despite lower absorption.
Study link: Selenium species-dependent toxicity, bioavailability and metabolic transformations in Caenorhabditis elegans - PMC
The Health Implications: It’s Complicated
The Good News (Mostly for Deficient Populations)
For people with genuine selenium deficiency, supplementation provides clear benefits:
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Essential for 25 selenoproteins including antioxidant enzymes
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Critical for thyroid hormone metabolism
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Supports immune function
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May reduce cardiovascular risk in deficient populations
A comprehensive review in Frontiers in Nutrition details how organic selenium from plants provides “greater bioactivities with less toxicity” compared to inorganic forms, making it the safer choice for addressing deficiency.
Study link: Selenium-enriched plant foods: Selenium accumulation, speciation, and health functionality - PMC
The Concerning News (For Already-Adequate Populations)
This is where the research gets sobering. The relationship between selenium and health follows a U-shaped curve—both too little AND too much are harmful.
Diabetes Risk: The Nutritional Prevention of Cancer (NPC) trial found that 200 µg/day of selenium supplementation increased type 2 diabetes risk by 55% (Hazard Ratio: 1.55). The effect was strongest in people with already adequate selenium levels, where risk increased 2.7-fold. A 2021 meta-analysis confirmed this, showing that blood selenium levels of 160 µg/L carried nearly double the diabetes risk compared to 90 µg/L.
Study link: https://www.acpjournals.org/doi/10.7326/0003-4819-147-4-200708210-00175
Cancer Prevention Failure: The massive SELECT trial (35,533 men) tested 200 µg/day of selenomethionine for prostate cancer prevention and found no benefit. Even more concerning, men with already high baseline selenium who supplemented showed increased risk of high-grade prostate cancer. The 2018 Cochrane Review of 83 studies concluded: “Selenium supplementation does not reduce overall cancer risk.”
Study link: Selenium and Vitamin E Cancer Prevention Trial (SELECT): Questions and Answers - NCI
The Narrow Therapeutic Window: Research published in the European Journal of Clinical Nutrition identified a protective range of only 55-145 µg/L blood selenium. Above 160 µg/L, health risks including diabetes increase significantly.
Study link: Selenium status and cardiovascular diseases: meta-analysis of prospective observational studies and randomized controlled trials | European Journal of Clinical Nutrition
Comparing the Two Forms
An animal study directly comparing organic versus inorganic selenium in cattle found that organic forms (selenomethionine and Se-yeast) were more effective at improving immune function and antioxidant capacity with no difference in growth or meat quality. However, the organic forms accumulated more readily in tissues.
Study link: Effects of organic and inorganic selenium on selenium bioavailability, growth performance, antioxidant status and meat quality of a local beef cattle in China - PMC
For toxicity, multiple studies show inorganic selenite causes “more severe” selenosis that “occurs sooner” than equivalent doses of organic forms. A toxicity review in broiler chickens found organic selenium toxic at ~7 mg/kg while inorganic was toxic at ~9 mg/kg body weight, but the inorganic form produced worse outcomes at high doses.
Study link: Comparison of toxic effects of dietary organic or inorganic selenium and prediction of selenium intake and tissue selenium concentrations in broiler chickens using feather selenium concentrations - ScienceDirect
Current Safety Guidelines
The U.S. sets the Tolerable Upper Intake Level at 400 µg/day, but Europe recently lowered theirs to 255 µg/day based on new toxicity data. The recommended daily amount is only 55 µg/day for adults.
NIH Selenium Fact Sheet: Selenium - Health Professional Fact Sheet
The European Situation: A Critical Geographic Difference
This is where things get really important for Europeans. North American soils are generally selenium-rich, but European soils are selenium-poor. This creates fundamentally different risk-benefit calculations.
A comprehensive 2015 systematic review found that “suboptimal Se status was reported to be widespread throughout Europe, the UK and the Middle East.” The data is striking:
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UK plasma selenium: 90.8 µg/L (below optimal)
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German plasma selenium: 82 µg/L (suboptimal)
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UK dietary intake: Only 29-39 µg/day (well below the 55-75 µg/day recommendation)
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Eastern Europe: Even lower status than Western Europe
Why the dramatic difference? UK wheat contains approximately one-tenth the selenium of US wheat (median 18 ng/g vs ~180 ng/g). Europeans historically imported selenium-rich wheat from North America, but the shift to locally-grown European wheat has caused a steady decline in selenium intake across the continent.
Study links:
Finland recognized this problem and became the only European country to add selenium salts to agricultural fertilizers, successfully raising population selenium levels.
Bottom Line: Geography Matters
For North Americans (US/Canada): Most people already get adequate-to-high selenium from food. Brazil nuts contain 68-91 µg per nut, seafood provides 24-92 µg per serving, and meat provides 18-37 µg per serving. For people who already have adequate selenium status, supplementation appears to provide no benefit and may increase diabetes and cancer risks.
For Europeans: The situation is reversed. With widespread suboptimal selenium status due to selenium-poor soils, modest supplementation or consumption of selenium-rich foods may be beneficial for many people—particularly those eating primarily locally-grown plant foods. The UK and German data suggest most Europeans are operating at the lower end of the adequate range or below it.
Regardless of location: The toxicity of inorganic forms (especially selenite) is significantly higher than organic forms at equivalent doses. If supplementation is needed, organic forms like selenomethionine or Se-enriched yeast are safer choices than inorganic selenite. The narrow therapeutic window (55-145 µg/L blood selenium) means it’s worth getting tested before supplementing, especially if you’re consuming Brazil nuts regularly or taking multiple supplements.
Key Research Papers Referenced:
