Phenylalanine is an amino acid most noted for being a precursor of tyrosine. At the deepest layers of the skin, tyrosine is the used to synthesize neurotransmitters such as dopamine, epinephrine and norepinephrine, as well as the skin pigment, melanin.
Where to Find Phenylalanine
Phenylalanine is obtained from protein-rich foods such as beef, poultry, fish, eggs, milk and milk products. It is also added to food and drink products. However, these must carry a special label noting its content of the amino acid. This warning label is required because some people cannot metabolize phenylalanine from food (phenylketonurics) (ProgressiveHealth).
The Mysterious Phenylalanine-Pigment Link
For years, it was widely believed that topically applying phenylalanine would supply skin with more tyrosine, which in turn would be used to create more melanin within the skin (ProgressiveHealth).
However, the truth of the matter is, phenylalanine is now known to be a melanin inhibitor, not a melanin enhancer. Phenylalanine has been noted to help to regulate the process by which too much melanin is processed within the skin.
Specifically, a form of phenylalanine known as undecylenoyl phenylalanine has novel mechanism by which it inhibits melanogenesis. It has been suggested that it does this by acting as an antagonist to alpha-melanocyte-stimulating hormone (MSH), which is an important component of the melanin-creating process. In the same double-blind, vehicle-controlled study, 2% UP was shown to have a moderate to marked improvement in the treatment of solar lentigines (Clinical and Experimental Dermatology, 2010).
In another (open-label) study done by Procter & Gamble, 1% undecylenoyl phenylalanine with 5% niacinamide was shown to be more effective than the 5% niacinamide formulation alone (Journal of Cosmetic Dermatology, 2009).
So, in truth, research shows phenylalanine will help to even out your skin tone — not increase your tan!
Based on this research, using a skin care regimen with phenylalanine regularly may help your skin even its tone. We recommend any of the AminoGenesis facial products in the dark-colored packaging to supply your skin with phenylalanine and 17 other amino acids!