Brazil Nuts and Selenium: How Many Brazil Nuts a Day Is Safe?

By the ProstateFoods editorial team · Last updated October 13, 2026 Short answer: One Brazil nut can contain roughly 68 to 91 mcg of selenium according to NIH, which is more than the 55 mcg adults need in a day [1]. USDA's average works out to about 96 mcg per nut [2]. Because the adult upper limit is 400 mcg a day from all sources, most people only need one or two Brazil nuts, and eating a large handful every day can push you over that limit [1].

Selenium in Brazil nuts by serving

Source: USDA FoodData Central SR Legacy, "Nuts, brazilnuts, dried, unblanched," 1,917 mcg selenium per 100 g, with USDA's 5 g per kernel and 28.35 g per ounce [2]. Selenium in Brazil nuts depends heavily on the soil where the trees grew, so any single nut can be well above or below the average.

Why the upper limit matters

The U.S. upper limit for adults is 400 mcg a day, and the European Food Safety Authority set a lower limit of 255 mcg in 2023 [1]. Getting too much selenium over time can cause problems such as a garlic smell on the breath, a metallic taste, hair and nail loss or brittleness, and skin rashes [1]. Remember that other foods, such as fish, eggs, meat and bread, also contribute selenium; see foods high in selenium.

What SELECT found about selenium and the prostate

The Selenium and Vitamin E Cancer Prevention Trial (SELECT) gave more than 35,000 men selenium, vitamin E, both, or a placebo. Selenium supplements did not lower prostate cancer risk [3]. Longer follow-up found that vitamin E supplements were linked to a higher risk [4]. The lesson for a food site: a nutrient that sounds protective in theory may not be, and more is not better.

Bottom line for your shopping list

• One or two Brazil nuts covers a day's selenium for most adults.
• Keep them in a mixed-nut jar rather than snacking on them by the handful.
• If you take a multivitamin or any supplement with selenium, count it too.

Forest Up raw, unsalted Brazil nuts are one option.

Sources

1. NIH Office of Dietary Supplements. Selenium: Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/Selenium-Consumer/
2. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy (2018). https://fdc.nal.usda.gov/
3. Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT). JAMA. 2009;301(1):39-51. https://pubmed.ncbi.nlm.nih.gov/19066370/
4. Klein EA, Thompson IM Jr, Tangen CM, et al. Vitamin E and the risk of prostate cancer: SELECT. JAMA. 2011;306(14):1549-56. https://pubmed.ncbi.nlm.nih.gov/21990298/

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ProstateFoods writes about food, not treatment. Nothing here is medical advice or a claim that any food treats, cures or prevents a disease. Talk to your doctor before changing how you eat, especially if you take medication or have a health condition. See our medical disclaimer. Photo: Bertholletia excelsa seeds closeup by רנדום, CC BY-SA 3.0, via Wikimedia Commons.