Amino acids play a fundamental role in nail health due to their involvement in the synthesis of keratin, the primary protein that makes up nails. Scientific studies have demonstrated that nails are composed predominantly of keratin, which is itself formed from various amino acids, including cysteine, methionine, and others. Deficiencies in dietary protein or specific amino acids can result in brittle, weak, or slow-growing nails, highlighting the biological necessity of adequate amino acid intake for normal nail growth and structure.

Some clinical research supports the use of amino acid supplementation (or increased dietary protein) in individuals with compromised nail health due to malnutrition or specific deficiencies. However, for individuals who already consume sufficient protein, there is limited evidence that additional amino acid supplementation leads to further improvements in nail strength or growth. The role of specific amino acids, such as cysteine, in promoting keratin production has been explored, but most evidence comes from biochemical and observational studies rather than large, randomized clinical trials.

In summary, there is scientific validation for the role of amino acids in supporting nail health, primarily through their necessity for keratin synthesis. However, the strength of evidence for amino acid supplementation in improving nail health in well-nourished individuals is moderate rather than strong.