A versatile and critical trace mineral, selenium plays many roles in the body. It acts as an antioxidant neutralizing damaging free radicals. It boosts immunity, ensures normal thyroid function, stimulates blood flow and protects against heart disease among its many other benefits. Selenium is found in the following keto-friendly foods: Brazil nuts, mushrooms, oysters, tuna, liver, and meat.
Even though it is abundant in these foods, selenium deficiency is actually a well-known complication of a long-term ketogenic diet.
A study of 110 children with epilepsy who were maintained on the ketogenic diet for more than 12 months were shown to have decreased levels of selenium.
Although the consequences are not usually severe, selenium deficiency can rarely become life-threatening. This was the case in a 5-year-old who had a normal selenium level before starting a ketogenic diet, but then developed cardiomyopathy (heart disease) and ventricular tachycardia, a fast and potentially life-threatening heart rhythm. It was suspected and confirmed by blood test that his selenium levels were severely deficient and his condition fortunately completely normalized and reversed after receiving immediate selenium supplementation.