Replenishing Amino Acids in Damaged Hair

The document from 2005 discusses the impact of amino acid loss on hair health and demonstrates that it is possible to replenish these amino acids through cosmetic treatments. Analysis techniques showed that 6 key amino acids are lost from hair during weathering, which includes mechanical, photochemical, and chemical damage. Experiments confirmed that these amino acids could be reintroduced into the hair shaft's cortical region, with their penetration confirmed by deuterium labeling and scanning focused ion beam analysis. The study found that the amount of amino acids reintroduced could be increased by using higher concentrations and more frequent applications, with leave-in treatments being particularly effective. The reintroduction of amino acids was shown to significantly improve the hair's tensile strength, suggesting long-term aesthetic benefits such as healthier appearance, feel, and reduced damage and breakage. The research was fully sponsored by The Procter and Gamble Company.