Amino acid in skin that initiates the production of melanin (melanin is the component of skin that gives it “color”). According to information on the FDA’s Web site (www.fda.gov), tyrosine’s “use is based on the assumption that it penetrates the skin, increases the tyrosine content of the melanocytes, and thus enhances melanin formation. This effect has not been documented in the scientific literature. In fact, an animal study reported a few years ago demonstrated that ingestion or topical application of tyrosine has no effect on melanogenesis [the creation of melanin].” Tyrosine is important to the structure of almost all proteins in the body. However, the chemical pathway needed for tyrosine to function is complex, and this pathway cannot be duplicated by including tyrosine in a skin-care product or by applying it topically.