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jacked guy bar curlingAmino Acids: Phenylalanine is an essential amino acid, meaning it is necessary for proper protein metabolism and body functions.  It is an amino acid that is well studied and comes in both a D and L form, which are isomers of each other and have very similar effects.  First, Phenylalanine helps curb appetite, which can be important for dieting and getting shredded.(1) Phenylalanine has been shown in numerous studies to effect mood and intensity, which makes it good for the bodybuilder who wants to increase “mental energy”. Phenylalanine may also increase the effectiveness of anti-depressant medications, further suporting it’s use as a mood enhancing agent.(2,3) It has also been shown to increase certain aspects of agression as well, making it good for a pre-workout supplement.(1) Phenylalanine may also increase the effectiveness of anti-depressant medications, further suporting it’s use as a mood enhancing agent.(4)  So, as a muscle building agent, phenylalanine isn’t implicated in any studies showing it to support anabolism, but as a neurotransmitter, appetite suppresant and mood enhancer, it is a very well supported and studied ingredient.


1: Appetite. 2008 Jul;51(1):111-9. Epub 2008 Feb 7.

Effects of L-phenylalanine on energy intake in overweight and obese women: interactions with dietary restraint status.

Department of Nutrition and Exercise Science, University at Buffalo, 15 Farber Hall, Buffalo, NY 14214-8001, United States.



2: J Am Osteopath Assoc. 1984 Sep;84(1 Suppl):119-23.// Links

Dietary supplements of phenylalanine and other amino acid precursors of brain neuroamines in the treatment of depressive disorders.

3: Psychosom Med. 1999 Sep-Oct;61(5):712-28.

Dietary supplements and natural products as psychotherapeutic agents.

Department of Health Care Sciences, George Washington University School of Medicine and Health Sciences, Washington, DC, USA.

4: Pharmacol Biochem Behav. 1977 Apr;6(4):475-8.

Effects of dietary tyrosine, phenylalanine, and tryptophan on aggression in mice.

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