A Brazil Nut a Day, Keeps the Free Radicals Away.
Selenium is a dietary mineral; it is important because it is a co-factor for the enzyme glutathione perioxidase. This enzyme reduces the number of free radicals in the body by trapping them, and thus its activity helps the body maintain good health. When levels of selenium are low, the enzyme can't work as well, meaning free radicals may run ramped, wrecking havoc on otherwise healthy cells. It is believed that free radicals contribute to cancer development, thus keeping them in-check is vital.
The importance of dietary Selenium is yet another example of how nutrition is just a heck of a lot of chemistry and biochemistry. Good thing I studied these subjects at great lengths during my undergraduate degree!
Selenium-rich foods include Brazil Nuts, Sunflower Seeds, Fish, Shellfish, Meat, Eggs, Mushrooms, Whole Grains, and Onions. Interesting fact: only one brazil nut may (depending on the soil in which it was grown) contain the daily required intake of selenium. Just one!
If possible, buy organic brazil nuts as these nuts are susceptible (similar to peanuts) to aflatoxin, a toxin made by mold that has been linked to causing liver cancer. Either eat brazil nuts plain, sprinkle on salads, or add them to your next batch of Roasted Rosemary Nuts.
Image source here.