Selenium Levels in Brazil Nuts: A Global Review of the Literature

Brazil nuts (BN, Bertholletia excelsa, Lecythidaceae) are frequently recommended for increasing selenium intake. Many individuals residing in regions with low soil selenium values, particularly including vegetarians, have selenium intakes below the dietary reference values. A literature review of selenium levels in BN was conducted to estimate their average selenium content and the number of BN that could help individuals with low selenium intakes reach dietary reference values. Based on published international data (1966-2025), a theoretical mean selenium concentration of BN was 29.1 (standard deviation: 41.1; range: 0.5-252.3) μg/g, with a median concentration of 14.9 μg/g (based on n = 148 values). BN purchased (or otherwise obtained) in Brazil suggest a somewhat higher mean selenium content (38.3 [range: 2.0-252.3] μg/g, median: 18.4 μg/g, n = 83), with lower mean selenium contents in studies of BN purchased in the USA (21.0 [range: 1.0-49.9] μg/g, median: 19.7 μg/g, n = 22) or Europe (15.3 μg/g [range: 0.5-122.7], median: 3.9 μg/g, n = 32). Sensitivity analyses using publication-level means and sensitivity analyses excluding studies analysing defatted or partially defatted BN confirmed the results. An intake of 2 to 10 BN/week, depending on the region, was derived as an intake range that, on average, would provide adequate amounts of selenium to supplement the diet of individuals with an otherwise low selenium intake. This quantity appears compatible with barium and radium levels in BN. The present work appears to be the first comprehensive review of selenium levels in BN. More extensive country-level data are needed to validate our preliminary recommendations.