Selenium

Selenium is a mineral with antioxidant properties. It is also vital for the proper functioning of the thyroid gland. Selenium may protect against lung, colorectal and prostate cancers but further research is needed before we fully understand the role of selenium in the development of cancers. The richest sources of selenium are seafood, meats, poultry, grains and grain products. However, you must be careful if you are taking selenium because too much selenium can cause serious medical problems that include nausea, diarrhea, fatigue, nerve damage in the hands and feet, and hair and fingernail loss.