Brazil nuts
Bertholletia excelsa
Seeds & Grains. Latin American & Amazon and Modern nutrition.
Also called Brazil nut, Castanha-do-Pará, Para nut
Pinyin: bā xī jiān guǒ
Spanish: Nuez de Brasil
Too much selenium is harmfulBrazil nuts are large, creamy seeds from a tall rainforest tree in the Amazon. They are one of the richest food sources of selenium.
Did you know? Brazil nuts grow inside a hard, woody pod about the size of a coconut, and the nuts inside are packed together like orange segments.
What it may help, and how strong the proof is
- Thyroid. Selenium is needed to make thyroid hormones. Trials of selenium pills lowered thyroid antibodies in some people with Hashimoto's disease, but the trials used pills rather than nuts, and clear clinical benefit is less certain.See the research: 1 study in peoplePromising proof
- Colds, flu & immunity. Selenium helps immune cells work. A clear benefit has only been seen in people who are short on selenium, and most people do not need extra.See the research: No trials in people found yetTraditional proof
- Men's health. Popular claims that selenium prevents prostate cancer were not supported. A large trial of selenium pills did not prevent prostate cancer.See the research: No trials in people found yetUnproven
Parts of the body
Traditional use
People in the Amazon have gathered Brazil nuts from the forest floor for generations. The nuts are a traditional food and a source of income for families in the region, and they are eaten fresh and used in cooking.
How it is classified
- Herbal actions
- Nutritive, Antioxidant. Energy: neutral.
How people take it
Adults need about 55 micrograms of selenium a day, and the upper limit from all sources is 400 micrograms a day. One nut often holds about 68 to 91 micrograms, which is already more than the daily need, and the amount varies widely. One or two nuts a day is a sensible limit.
Food and oil.
Where to get it
Brazil nut trees grow wild in the Amazon forest of Brazil, Peru and Bolivia. Most nuts are gathered from wild trees, because the trees do not grow well on farms. They are sold shelled, raw or roasted, in mixed nuts, as butter, and as oil.
Be careful
Too much selenium is harmful. Regular heavy intake can cause selenosis, with hair loss, brittle nails, garlic breath, rash, nausea, tiredness and nerve problems. Because selenium varies so much from nut to nut, a handful can be much higher than another. Do not add selenium pills on top of daily Brazil nuts without a doctor's advice. Food amounts are generally fine in pregnancy, but high intake should be avoided.
Avoid if: tree nut allergy; selenium supplements.
Mixing with other things
No specific mixing notes on file. That doesn't prove it's safe with everything; ask a pharmacist about your full list.
The honest take
Brazil nuts are a rich and tasty source of selenium, a mineral the body needs in small amounts. The nut itself is not a cure for anything, and the selenium in each nut varies widely. Trials of selenium pills give mixed results for the thyroid and show no protection against prostate cancer, so one or two nuts a day is a sensible amount.
Sources
Each “See the research” link opens PubMed, the U.S. National Library of Medicine's index of medical studies, showing only trials and reviews done in people. The number tells you how much a use has been tested, not whether it worked. The proof rating tells you that.
Study counts checked October 2026.