The importance of adequate stores of the amino acid methionine cannot be underestimated. Methionine is particularly important because it supplies sulfur–a mineral–that helps to maintain healthy skin tone, well-conditioned hair, and strong nails. Because your body can’t produce this essential amino acid on its own, you must get it from methionine-rich foods, such as cheddar cheese, eggs, chicken, and beef. Supplements are also a source.