Selenium is an essential micronutrient for thyroid hormone production, DNA synthesis, reproduction and healthy immunological system.
Recommended Dietary Allowances (RDAs) for Selenium‡ :
‡ The amalgam of recommendations by the National Institute of Health, USA and the Department of Health, UK aiming for the highest intakes
*Adequate Intake (AI)
Examples of plant based sources:
(Source: https://fdc.nal.usda.gov/)
*The selenium content found in soils varies between and within countries.
The above is based on USDA data and it may not reflect the selenium content in other part of the world.
Taking a supplement is the most reliable way of obtaining selenium because of the considerable variability of selenium in plant foods. Even Brazil nuts which are famed for being a rich source of selenium cannot be completely relied on because of this problem1.
References
1. Junior, E.S., Wadt, L.D.O., Silva, K.E., Lima, R.M.B., Batista, K.D., Guedes, M.C., Carvalho, G.S., Carvalho, T.S., Reis, A.R., Lopes, G. and Guilherme, L.R.G., 2017. Natural variation of selenium in Brazil nuts and soils from the Amazon region. Chemosphere, 188, pp.650-658. (https://repositorio.unesp.br)