But perhaps the most significant finding in relation to selenium is its protective effects against certain kinds of cancer. It has been found that a tenfold increase in dietary selenium causes a doubling of glutathione peroxidase, which disarms oxides, in the body. Since many oxides, for example from smoking or deep-fried food, are cancer-producing, and since cancer cells destroy other cells by releasing oxides, it is likely to be selenium' s role in promoting glutathione peroxidase that gives it its protective properties against cancer. Selenium may also be essential for the working of the thyroid gland, which controls the body' s rate of metabolism.

I recommend supplementing 30mcg of selenium a day, minimum. There is a good case, however, for supplementing lOOmcg and even double this amount if you are at risk of cancer or fighting an infectious disease. Selenium is found predominantly in wholefoods, seafoods, seeds (especially sesame seeds) and nuts, but food sources, which should provide up to 50mcg a day, are unreliable.