Nutrition Science and Everyday Application - beta v 0.1

VITAMINS AND MINERALS AS ANTIOXIDANTS 483
some nuts contain selenium when grown in selenium-containing soils. The selenium content
of the soils used to grow animal feed can also affect the selenium content of animal
products.
Figure 8.18. Dietary sources of selenium. Source: NIH Office of Dietary Supplements
Selenium Deficiency and Toxicity
Selenium deficiency is very rare in the United States and other developed countries.
Worldwide, people with a primarily vegetarian diet in areas with low soil selenium levels,
including parts of China and Europe, may be at risk for selenium deficiency. 6
Chronic exposure to foods grown in soils containing high levels of selenium (above the UL
of 400 micrograms per day) can cause brittle hair and nails, gastrointestinal discomfort, skin
rashes, halitosis, fatigue, and irritability. Brazil nuts contain very high levels of selenium, so if
eaten regularly could cause selenium toxicity. Selenium at doses several thousand times the
RDA can cause acute toxicity, and when ingested in gram quantities, can be fatal.
Self-Check: