Phenylalanine
Phenylalanine is an essential amino acid, which means that it must be obtained through the diet in adequate quantities to meet the body's needs. It is a precursor of the neurotransmitters epinephrine, norepinephrine and dopamine. Phenylalanine has a role in the treatment of depression, chronic pain, arthritis, vitiligo (a skin pigment disorder) and cancer. Good sources of phenylalanine are fish, meat, eggs, milk and milk products, soy and soy products, and nuts and seeds. (For more detailed information, please visit ISM’s searchable database: Nutraceutical Search.)
Twenty three subjects with endogenous depression after a previous unsuccessful treatment with common antidepressive drugs (imipramine-like or MAO inhibitors) dl- or d-phenylalanine was given in daily oral doses of 50 or 100 mg during 15 days. A complete euthymia was obtained in 17 subjects between one and 13 days of treatment. No important adverse reaction was observed.
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Fischer, E, Heller, B, Nachon, M & Spatz, H (1975). Therapy of depression by phenylalanine. Preliminary note. Arzneimittelforschung. 25(1), 132.The antidepressive efficacy of 1-deprenyl (5-10 mg daily) plus 1-phenylalanine (250 mg/day) has been evaluated in 155 unipolar depressed patients. Both oral and intravenous administration showed beneficial effects in 90% of outpatients and 80.5% of inpatients. It is concluded that this combined treatment has a potent antidepressive action based on the accumulation of 1-phenylethylamine in the brain.
o Birkmayer, W, Riederer, P, Linauer, W & Knoll, J (1984). L-deprenyl plus L-phenylalanine in the treatment of depression. J Neural Transm. 59(1), 81-7.
It has been claimed that the mechanism of acupuncture analgesia can be explained in part by endogenous opioids. If so, it might be possible to enhance the analgesic effect of acupuncture by the administration of endorphins. If D-phenylalanine (DPA), an inhibitor of the endorphin degrading enzyme, is administered, the analgesic effect of acupuncture should be prolonged due to the increased level of endorphins. From the changes of the pain threshold (PT), we investigated whether or not the pre-administration of DPA can enhance the analgesic effect of acupuncture in humans. In addition, we examined the inhibitory effect of naloxone. 1) In all five subjects whose PT was raised after acupuncture anesthesia (respondents), the rise in PT was significantly prolonged by DPA. 2) Out of 10 subjects whose PT remained almost unchanged after acupuncture anesthesia (non-respondents), the PT was increased by DPA in 5 cases. 3) The rise in PT was most prominent when DPA was administered 30 minutes before the start of acupuncture anesthesia. 4) In all 4 respondents in whom the rise in PT persisted after DPA and acupuncture anesthesia, their raised PT dropped after the intravenous injection of naloxone (10 mg). 5) These findings show that DPA enhances the analgesic effect of acupuncture by the "endorphin mechanism."
o Kitade, T, Odahara, Y, Shinohara, S, Ikeuchi, T, Sakai, T, Morikawa, K, Minamikawa, M, Toyota, S, Kawachi, A, Hyodo, M, et al. (1988). Studies on the enhanced effect of acupuncture analgesia and acupuncture anesthesia by D-phenylalanine (first report)--effect on pain threshold and inhibition by naloxone. Acupunct Electrother Res. 13(2-3), 87-97.
D-phenylalanine (DPA) is known to block the activity of carboxypeptidase, an enzyme which degrades enkephalins, endogenous morphine-like substances. Therefore, it is considered that DPA administered as an inhibiting drug of this degrading enzyme might prolong analgesia induced by acupuncture. 1) Thirty patients suffering from chronic low back pain were treated with acupuncture 30 minutes after the oral administration of 4.0 grams of DPA………. The results from the "excellent", "good" and "fair" cases showed a 16% increase in effectiveness when DPA was administered the day before, not a statistically significant difference (P less than 0.1), but a clear tendency to increase was observed. The above findings show that DPA has an enhancing effect on acupuncture analgesia and anesthesia in clinical practice.
o Kitade, T, Odahara, Y, Shinohara, S, Ikeuchi, T, Sakai, T, Morikawa, K, Minamikawa, M, Toyota, S, Kawachi, A, Hyodo, M, et al. (1990). Studies on the enhanced effect of acupuncture analgesia and acupuncture anesthesia by D-phenylalanine (2nd report)--schedule of administration and clinical effects in low back pain and tooth extraction. Acupunct Electrother Res. 15(2), 121-35.
BACKGROUND: Vitiligo is a hypopigmentation disorder affecting 1 to 4% of the world population. Fifty percent of cases appear before the age of 20 years old, and the disfigurement results in psychiatric morbidity in 16 to 35% of those affected. METHODS: Our objective was to complete a comprehensive, systematic review of the published scientific literature to identify natural health products (NHP) such as vitamins, herbs and other supplements that may have efficacy in the treatment of vitiligo…………… CONCLUSION: Reports investigating the efficacy of NHPs for vitiligo exist, but are of poor methodological quality and contain significant reporting flaws. L-phenylalanine used with phototherapy, and oral Ginkgo biloba as monotherapy show promise and warrant further investigation.
o Szczurko, O & Boon, HS (2008). A systematic review of natural health product treatment for vitiligo. BMC Dermatol. 22(8), 2.