SELENIUM
Selenium is widely distributed throughout the body, with high concentrations in the kidneys, liver, and testicles. Selenium-containing enzymes - notably the vital antioxidant glutathione peroxidase - play a major role in protecting the integrity of cell membranes and the immune system, and they help maintain the function of the thyroid gland and the heart.⁵ An interesting aspect of the selenium in glutathione peroxidase is that it is synergistic with vitamin E (another antioxidant); consequently, a deficiency in either of these nutrients can create additional requirements for the other.⁴ Selenium has been shown to increase sperm motility (and hence the probability of conception) in subfertile men with low selenium levels.¹³ And there appears to be strong evidence that a low selenium intake is associated with higher cancer rates, suggesting that an adequate selenium intake may be essential for cancer prevention.¹⁴ A reasonable amount of supplemental selenium is 200 mcg/day.