Selenium is incorporated into selenoproteins that include glutathione peroxidase, the most important intracellular antioxidant enzyme, thioredoxin reductase which regenerates other antioxidants, and deiodinases which convert inactive T4 thyroid hormone to the active T3 form. Selenium deficiency impairs all three functions simultaneously. UK soils are relatively selenium-poor compared to North American soils, and selenium intake from UK food chains is often below optimal.
The Brazil Nut Solution
Brazil nuts from the Bertholletia excelsa tree are exceptional selenium accumulators due to the selenium-rich soils of the Amazon basin. A single Brazil nut provides approximately 95 micrograms of selenium, equivalent to nearly double the UK recommended daily intake of 55 micrograms. Two Brazil nuts per day reliably meets selenium requirements without risk of toxicity (which begins above 400 micrograms per day). This is one of the most practical single food recommendations in nutrition.
Beyond Brazil Nuts: Other Selenium Sources
- Tuna and sardines: approximately 80 to 90 micrograms per 100 grams
- Egg yolks: approximately 15 to 20 micrograms each
- Chicken and turkey: approximately 25 to 30 micrograms per 100 grams
- Whole grains from selenium-rich soils: variable but meaningful contribution in a mixed diet
- Kidney: one of the most selenium-dense organ meats at 140 micrograms per 100 grams