The Study
Improving the selenium supply of vegans and omnivores with Brazil nut butter compared to a dietary supplement in a randomized controlled trial
This study gave people either Brazil nut butter or a selenium pill and saw if their blood selenium levels went up. It found that both worked well, so we can say these things probably help raise selenium levels. But it didn’t test if this makes people healthier or prevents sickness.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
This study tested if eating Brazil nut butter works as well as taking a selenium pill to fix low selenium levels in people who don't eat meat.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 570 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means eating just two Brazil nuts a day (as nut butter) can raise selenium levels as much as a daily supplement, which matters for vegans who often lack selenium.
- 2Vegans and omnivores who ate 15g of Brazil nut butter or took a supplement daily for two weeks saw their selenium levels rise by 15–19 µg/L.
- 3SELENOP (a key selenium protein) went up by 1.4–1.9 mg/L — more in vegans.
- 4The pill and nuts worked equally well.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Nutrition
Year
2025
Authors
Rebecca Simon, Kristina Lossow, Denny Pellowski, Kristin Kipp, Michaela Achatz, N. Klasen, Tanja Schwerdtle, Christine Dawczynski, A. Kipp
Related Content
Claims (6)
Taking 55 micrograms of selenium daily for two weeks from Brazil nut butter or a selenium supplement raises blood selenium levels by 15–19 micrograms per liter in adults with low baseline selenium, regardless of whether they follow a vegan or omnivorous diet.
In vegans with low selenium levels, eating Brazil nut butter or taking selenium supplements raises selenoprotein P levels by 1.4–1.9 mg/L within two weeks, and this increase is larger in vegans than in people who eat meat.
People following a vegan diet in Europe have lower selenium intake and lower selenium levels in their blood than people who eat meat and animal products, resulting in a higher rate of selenium levels below what is considered optimal for health.
Brazil nut butter raises selenium levels in the body similarly to selenium supplements, but it costs more per day and contains inconsistent amounts of selenium between batches, making it less reliable for daily use.
Eating two Brazil nuts daily delivers the same amount of usable selenium as taking a 100-microgram selenomethionine supplement.
In people who follow a vegan diet, taking selenium supplements raises the activity of the enzyme GPX3, but this does not happen in people who eat meat and dairy. The enzyme GPX3 does not respond as strongly to selenium levels as another protein called SELENOP.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.