Bertholletia excelsa. A giant rainforest tree of the Amazon whose seeds, the Brazil nuts, concentrate selenium from the soil.
What the research supports
In a 2008 trial, two Brazil nuts a day raised selenium levels and antioxidant enzyme activity as well as a 100 mcg selenium supplement. A tiny 2013 study found improved cholesterol after a single large serving. The large SELECT trial found that extra selenium did not prevent cancer.
The dose that was actually studied
Two nuts a day, about 100 mcg of selenium, for 12 weeks. The safe upper limit for adults is 400 mcg of selenium a day from all sources.
What to look for on a label
- Fresh, raw or soaked and dried nuts; store in the fridge or freezer
- Organic certification if possible
Who should not eat large amounts
- Anyone already taking a selenium supplement or multivitamin with selenium
- Children, who have a much lower upper limit
- People with a thyroid condition, without their doctor’s advice
Read the full guide: Brazil Nuts for Selenium: Why Two a Day Is Enough.
This profile is for general education and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you take medication or have a health condition.
