Brazilian nuts are the richest food source of selenium. One medium-size nut provides more than the recommended dietary allowance of selenium, an essential nutrient your body cannot produce. Staying healthy requires that your immune system functions at its optimum level and selenium helps fight free radicals and boosts the immune system. Selenium is also attributed to helping to prevent bone, prostate, colorectal, and breast cancer. A deficiency of selenium can lead to an increased risk of developing bladder, lung, stomach, esophagus, and liver cancer. Adults with digestive health issues such as Crohn’s disease, celiac disease, or those who are experiencing serious inflammation and chronic infection issues are likely to be deficient in selenium. An adequate intake of selenium is also essential for your thyroid to function properly, which is necessary for optimal health. Brazil nuts can help you easily ensure adequate intake of this vitally important nutrient.