A trace mineral that acts as an antioxidant in combination with glutathione peroxidase and Vitamin E, selenium inhibits platelet aggregation and in turn protects against stroke and heart disease. It is a free radical scavenger and is thought to delay the division of cancer cells, giving the body time to repair before the division of more malignant cells.
In countries where the soil content of selenium is low, there is higher incidence of certain diseases. In the United States the south-western stroke belt of Georgia and Carolina has the lowest level of selenium in the soil in the country. In China selenium in the soil varies widely over the vast distances but rates of cancer of the oesophagus, stomach and liver are higher where the selenium soil content is lowest. New Zealand soils are selenium deficient and research has found rates of asthma increase where blood selenium is below a certain level. A Finnish study showed people with a selenium deficiency had three times the chance of having a stroke.
The maximum daily dose of selenium is 200 mcg a day. More than this amount may be toxic. Normally 100 mcg is enough. There is a risk that more than 100 mcg could exacerbate an iodine deficiency.
Selenium is found naturally in whole grain wheat. Garlic is an important source, also onions, red meat, chicken, shellfish, fish, broccoli, Brazil nuts and brewer’s yeast.