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Phenylalanine is an essential amino acid. Because it can cross
the blood-brain barrier, it can have a direct effect on brain chemistry.
Phenylalanine can be converted into another amino acid, tyrosine,
which in turn is used to synthesize two key neurotransmitters that
promote alertness: dopamine and norepinephrine.
This amino acid can elevate mood, decrease pain, aid in memory
and learning, and suppress the appetite. It can be used to treat
arthritis, depression, menstrual cramps, migraines, obesity, Parkinson's
disease, and schizophrenia.
In a dose of 500-3,000 mg, phenylalanine, along with vitamin B6,
produced an almost immediate improvement in thirty-one out of forty
depressed patients. In addition to phenylalanine's role in making
adrenaline mimickers, it provides spirit-boosting endorphins. Phenylalanine
is the only substance that the body can use to make phenylethlamine
(PEA). Low PEA level's in depressed subjects show that phenylalanine
is not being metabolized.
Taking 500-1,000 mg of phenylalanine on an empty stomach can assist
in caffeine withdrawal. Phenylalanine is a very good substitute
eye-opener. Anyone who wants to enhance alertness may try it. Studies
repeatedly show that it works under a variety of conditions.
Research backs the use of phenylalanine to alleviate arthritis
aches, back pain, and menstrual cramps, especially in the DL-form.
It slows the body's breakdown of endorphins and other natural painkillers,
so their effects will last longer.
Phenylalanine also controls inflammation and may even enhance the
work of analgesic medications. Daily doses of 1-3 grams work better,
when combined with a diet free of foods that foster inflammatory
reactions, including sugar, safflower oil, sunflower oil, corn oil,
and overfried foods.
A number of studies have concluded that L-phenylalanine can promote
skin repigmentation, helping to diminish the faded blotches caused
by vitiligo. Creams containing the amino acid work rather well.
To enhance the results, use the nutrient with some copper, which
the body needs to produce melanin, a natural pigment.
A few isolated studies indicate that phenylalanine may be used
against multiple sclerosis or Parkinson's disease. Researchers found
that the amino acid significantly reduced the severity of Parkinson's
symptoms like depression, speech impediments, limb rigidity, and
walking difficult. The hand tremors, however, continued. The participants
in this study took 1,250 mg of the amino acid twice a day for just
four weeks.
Deficiency: Symptoms of phenylalanine deficiency
may include confusion, emotional agitation, depression, decreased
alertness, decreased memory, behavioral changes, decreased sexual
interest, bloodshot eyes, and cataracts. If not corrected by supplemental
dietary phenylalanine and tyrosine, the deficiency may lead to restricted
weight gain and stunted growth, osteopenia, anemia, alopecia, and
even death.
Sources: Generally, phenylalanine is found in cheeses;
nuts and seeds; milk chocolate; meat (excluding fat), particularly
organ meats; poultry (excluding skin); fish, including shellfish;
milk; and eggs. The most concentrated sources are torula yeast,
soybean protein isolate, soybean protein concentrate, peanut flour,
dried spirulina seaweed, defatted and low-fat soybean flour, dried
and salted cod, defatted soy meal, dried and frozen tofu, Parmesan
cheese, almond meal, dry roasted soybean nuts, dried watermelon
seeds, and fenugreek seeds.
Precautions:
- Anxiety, headaches, and hypertension are possible side effects
of supplementation.
- Individuals with PKU and women who are lactating or pregnant
should avoid supplementation.
- L-dopa competes with phenylalanine and should not be taken at
the same time of day.
- Little is known about the use of aspartame (Nutrasweet) during
pregnancy.
Dosage Ranges and Duration of Administration: The
following are the recommended dietary allowances for phenylalanine
plus tyrosine, according to the National Research Council:
- Birth to 4 months: 125 mg/kg/day
- 5 months to 2 years: 69 mg/kg/day
- 3 to 12 years: 22 mg/kg/day
- Adults and teenagers: 14 mg/kg/day
Based on obligatory amino acid losses (including data from amino
acid tracer studies), it has been suggested that adults need 39
mg/kg/day.
Nutritional doses are 0.75 to 2 g per day; therapeutic doses are
2 to 3 g per day; experimental doses are 4 to 5 g per day.
INTERACTIONS
Baclofen
In situ, phenylalanine (up to 100 mM) decreased the absorption of
isotonic perfusion solutions of baclofen (0.5 mM) in the rat small
intestine by 67% (Cejudo-Ferragud et al. 1996). To maximize absorption
of the drug, baclofen should not be administered with meals, especially
meals high in protein content.
18F-DOPA
Infusion of L-phenylalanine prior to administration of 3-O-methyl-6-[18F]fluoro-L-DOPA
(18F-DOPA) prevented 18F-DOPA uptake in the brain (Doudet et al.
1992). L-phenylalanine improved specific-to-non-specific contrast
images of 18F-DOPA during positron emission tomography (PET) scanning.
Levodopa
Administration of levodopa (1 mg/kg/hour IV) following administration
of phenylalanine (100 or 200 mg/kg po) in two patients with advanced
Parkinson's disease altered the clinical effects of the drug (Woodward,
et al. 1998). The therapeutic response to levodopa could be diminished
when administered at the same time as phenylalanine |
