Life Extension D,L-Phenylalanine Capsules, 500 mg, 100 Vegetarian Capsules

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Life Extension D,L-Phenylalanine Capsules are an amino acid that is required for good health but the body cannot make on its own. It helps to create norepinephrine and epinephrine (adrenaline) to support stress, depression, and mental energy.

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L-phenylalanine is an essential amino acid that can be converted to L-tyrosine in the liver. L-tyrosine can be converted in the brain and in the adrenal glands to norepinephrine, and epinephrine (adrenaline) hormones that are depleted by stress, overwork and certain drugs. By replenishing norepinephrine in the brain, mental energy levels are enhanced and a feeling of contentment often occurs. The conversion step from L-tyrosine to norepinephrine may be enhanced if the co-factors (vitamins B6 and C) are included.163-169

Cells in the adrenal medulla synthesize and secrete norepinephrine and epinephrine. Since both norepinephrine and epinephrine can cause smooth muscle (arterial) contraction, care with blood pressure should be taken when supplementing with L-phenylalanine or tyrosine.

D,L-phenylalanine is a 50/50 mixture of its two stereoisomers.

As stated previously, Phenylalanine is an essential amino acid. An amino acid is a building block for proteins and an essential amino acid is one the body requires but cannot make itself. You must get it from food or supplements. L-phenylalanine is found in foods high in protein while D-phenylalanine is created in a laboratory. Life Extension D,L-Phenylalanine Capsules is a combination frequently notated as DL-phenylalanine. This mixture is needed to help with both pain and depression.1-3


Supplement Facts

Serving Size: 1 vegetarian capsule

Servings Per Container: 100

Amount Per Serving
D,L-phenylalanine 500 mg
Other Ingredients: vegetable cellulose (capsule), microcrystalline cellulose, vegetable stearate.

Dosage and Use:

  • Take one capsule daily on an empty stomach in the morning, or as recommended by a healthcare practitioner. Best utilized if taken with the co-factors vitamins B6 and C.

Caution: May cause anxiety, high blood pressure, and headache. Do not use if you have phenylketonuria. Do not use phenylalanine or tyrosine if you have cancer or muscular dystrophy. Because phenylalanine can elevate blood pressure in hypertensives, consult your healthcare practitioner if you have hypertension. Insomnia may occur from overstimulation if taken too close to bedtime.


  • If pregnant, nursing, or taking medication, consult your physician before taking this product
  • Keep out of reach of children
  • Do not exceed recommended dose


1. WebMD: Phenylalanine
2. Dl-phenylalanine in depressed patients: an open study.
3. Wikipedia: Phenylalanine
163. J Psychiatry Neurosci. 2001 May;26(3):247-51.
164. Acta Paediatr Suppl. 1994 Dec;407:86-8.
165. Med Sci Sports Exerc. 2001 Dec;33(12):2104-10.
166. Brain Res Bull. 1999 Jan 15;48(2):203-9.
167. Pharmacol Biochem Behav. 1976 Jul;5(1):47-53.
168. Clin Neuropharmacol. 2000 Jul-Aug;23(4):212-5.
169. Aviat Space Environ Med. 1992 May;63(5):364-9.


* These statements have not been evaluated by the Food and Drug Administration. This Product is not intended to diagnose, treat, cure or prevent any disease.



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