Research suggests that Brazil nuts, as a naturally rich source of organic selenium, may offer some benefits for thyroid-related health markers, particularly by supporting selenium status and antioxidant activity, with one randomized controlled trial noting that Brazil nut flour consumption was associated with stable free T3 levels compared to a decline in the placebo group. A 2022 systematic review of 24 clinical studies found consistent improvements in selenium levels and antioxidant markers across various populations, with hemodialysis patients showing improvements in thyroid function specifically, though the authors noted that most included studies were non-randomized, limiting the strength of conclusions. Studies also indicate that Brazil nuts may be relevant for thyroid cancer patients on low-iodine diets as an iodine-free source of organic selenium, though this observation comes from a letter to a journal editor rather than a controlled trial. Findings are mixed overall, as a 2018 review raised substantive concerns about the risks associated with Brazil nut consumption, including selenium toxicity from overconsumption, potential aflatoxin contamination, allergic reactions, and a possible association between high selenium intake and type 2 diabetes, underscoring that the unusually high selenium content of these nuts means the margin between benefit and risk warrants careful consideration.
Citations from PubMed and preprint sources. Match score (0-100) reflects automated search ranking, not clinical appraisal.
| Title | Type | Year | Direction | Match |
|---|---|---|---|---|
| Commentary: Health Concerns of Brazil Nut Consumption. | Other | 2018 | Mixed | 72 |
| Effects of Regular Brazil Nut (Bertholletia excelsa H.B.K.) Consumption on He... | Review | 2022 | Supports | 67 |
| Differentiated thyroid cancer and selenium supplements for protection of sali... | Other | 2018 | Supports | 62 |
| Intake of partially defatted Brazil nut flour reduces serum cholesterol in hy... | RCT | 2015 | Supports | 57 |