Brazil nuts are important in a cancer preventive diet especially because of their high concentrations of the trace mineral selenium. Selenium functions with antioxidant enzymes to increase the antioxidant capacity of other vitamins in the body, and is important in regulation of thyroid hormone. In cancer prevention, selenium is needed to repair DNA or promote cell death in damaged cells, inhibit the spread of new cancer cells, and it promotes liver detoxification. A low selenium level is implicated in many types of cancers. Two Brazil nuts per day provide a minimum dietary requirement.