L-phenylalanine facilitates the release of the hunger-suppressing hormone cholecystokinin in the body and is possibly effective as an appetite suppressant when taken shortly before a meal, according to a 1994 study published on PubMed.gov. L-phenylalanine occurs naturally in meat, fish and dairy foods, notes WebMD.
L-phenylalanine is an essential amino acid that is in a variety of foods including meat, eggs, fish, cheese and milk, notes WebMD. It may be effective for the treatment of vitiligo; however, more research is necessary to prove its effectiveness for this and other applications.
A 1994 study looking at a small group of human subjects suggests that L-phenylalanine taken by mouth 20 minutes prior to a meal causes a reduction in calorie intake at that particular meal. In the study, participants received either D-phenylalanine, L-phenylalanine, or a placebo, then they ate meals of known caloric content. The participants who received L-phenylalanine consumed fewer calories on average than those in the D-phenylalanine or placebo groups, as detailed on PubMed.gov.
L-phenylalanine triggers the release of cholecystokinin, a satiety hormone, upon consumption. Taking L-phenylalanine prior to a meal may cause the person to feel full sooner, causing him to eat less during the meal, notes Smart Publications.