Phenylalanine Overview:

       Phenylalanine is an necessary amino acid (a building block of proteins inside the human body), which means body needs it for your health can't make it. A person needs to get it from food. Phenylalanine can be found in 3 forms: L-phenylalanine, the natural form which is found in proteins; D-phenylalanine (which is a mirror image of L-phenylalanine which is usually made in the a laboratory), and DL-phenylalanine,the combinaton of` the two forms.

Your body transforms phenylalanine into tyrosine, which is another amino acid that is needed to produce proteins, brain chemicals which includes L-dopa, epinephrine, and norepinephrine, and also thyroid hormones. Since norepinephrine has an effect on mood, various forms of phenylalanine have been suggested to treat depression. Signs and symptoms of phenylalanine insufficiency include confusion, loss of energy, depression, diminished alertness, memory troubles, and absence of appetite.

In the other hand, there is a rare metabolic disorder called phenylketonuria (PKU) that occurs in people whic lacks an enzyme in the body that is needed for phenylalanine utilization. This causes high levels of phenylalanine to build up in the body.If this is not treated before 3 weeks of age, PKU can may cause severe and permanent mental retardation. In the United States , newborns are usually tested for PKU within the first 48 - 72 hours of life. People with PKU should eat a selected diet avoiding phenylalanine. They should also take tyrosine supplements for optimimal brain development and growth.

Uses of Phenylalanine

Chronic pain - D-phenylalanine (but not L-phenylalanine) has been used to treat chronic pain. However, the latest studies did not show any good evidence that this treatment works. There are two studies that seem to show positive results but it had flaws which made the findings not reliable. Other clinical reports have found out that D-phenylalanine is no more effective than a placebo in reducing pain.

Parkinson's disease – In one animal study, researches suggests that D-phenylalanine may improve rigidity, disability in walking, speech difficulties, and depression that is associated with Parkinson's disease. But there is no solid evidence yet if it would have the same positive effect in humans. Therefore, More research is needed.

Vitiligo - Some preliminary studies reported that L-phenylalanine (both oral and topical) boosts the effect of UVA radiation for people suffering vitiligo. Vitiligo is a rare condition where there is irregular depigmentation (loss of color) causing white patches of skin. L-phenylalanine use can lead to some skin darkening or repigmentation of these white skin patches, particularly on the facial area.

Depression – There are some clinical studies which suggests that phenylalanine could be helpful as part of a multiple therapy for depression. However, as most of the studies were actually done in the 1970s and 1980s and were not thoroughly tested. There are people who have reported that their mood had improved when they took phenylalanine supplements.

Dietary Sources:

L-phenylalanine can be found in most foods containing protein like for example beef, poultry, pork, fish, milk, yogurt, eggs, cheese, soy products (including soy protein isolate and proudcuts, soybean flour, and tofu), and certain nuts and seeds. The artificial sweetener aspartame which is common in diet Pepsi and diet Coke is also high in phenylalanine.

D-phenylalanine is made only in the laboratory and cannot be found in food.

Available Forms:

D-phenylalanine

L-phenylalanine

DL-phenylalanine (50/50 mixture of D-phenylalanine and L-phenylalanine)

Phenylalanine may be taken as a capsule, powder, or in tablet form. This supplement can also be used as a topical cream.

How to Take It:

The recommended dosages of phenylalanine may vary depending on the health condition that is being treated. Take phenylalanine supplements 15 - 30 minutes before meals. The average daily recommended dietary allowances (RDAs) for L-phenylalanine are as follows. Note that this is for getting your phenylalanine from food, not on supplements.

Pediatric

Infants 0 - 4 months: 125 mg per kilogram of body weight

Children 5 months - 2 years: 69 mg per kilogram of body weight

Children 3 - 12 years: 22 mg per kilogram of body weight

The combination of both oral and topical phenylalanine (plus ultraviolet light) is also used to treat children suffering from vitiligo. The dose is determined by a doctor.

Teenagers and adults: 14 mg per kilogram of body weight

Some medical experts suggest that grown ups may need as much as 39 mg per kilogram of body weight per day for health and wellness. Doses as high as 50 - 100 mg per kilogram have also been used in studies involving the treatment of vitiligo. The typical amounts used range from 750 - 3,000 mg per day for adults.

Precautions:

• Because of the possibility of side effects and interactions with other medications, dietary supplements like phenylalanine should be taken only under the medical supervision of a health care provider.

• People suffering from phenylketonuria (PKU) and women that are breastfeeding or are pregnant should never take phenylalanine supplements. Aspartame, which is found in artificial sweeteners like Nutrasweet, is also source of phenylalanine. People with PKU should never use aspartame. If you are pregnant or is planning to get pregnant, ask your doctor about using artificial sweetener in your diet.

• DL-phenylalanine should never be used in people taking antipsychotic drugs. This may cause or worsen the symptoms of tardive dyskinesia. Tardive dyskinesias (TDs) is a sickness which causes involuntary movements of the tongue, lips, face, trunk, and limbs this can occur in individuals taking antipsychotic drugs in the long term.

• DL-phenylalanine may also cause symptoms of anxiety, hyperactivity in children and jitteriness.

• Doses that are higher than 5,000 mg a day can be toxic and can cause severe nerve damage. High doese of DL-phenylalanine may also cause mild side effects like nausea, heartburn, and headaches.

Possible Interactions:

• If you are being treated with any of the medications listed below, you should also not use phenylalanine without first consulting your doctor.

• Monoamine Oxidase Inhibitors -- Monoamine oxidase inhibitors (MAOIs) are an old class of antidepressants drugs which are rarely used today. MAOIs include phenelzine (Nardil), isocarboxazid (Marplan), and tranylcypromine sulfate (Parnate). Taking phenylalanine supplements while taking MAOIs can cause a severe increase in your blood pressure (hypertensive crisis). This increase in blood pressure may lead to a heart attack or stroke. People who are taking MAOIs should also avoid foods and supplements that contains phenylalanine.

• Baclofen -- Phenylalanine may also reduce the absorption of baclofen (Lioresal), this is a medication that is used to relieve spasms of the muscle. Avoid taking Baclofen during and after meals, especially meals that are high in protein, or with phenylalanine food supplements.

• Levodopa – There are few case reports that suggest that phenylalanine may reduce the effectiveness of levodopa (Sinemet), this is a medication that is used to treat Parkinson's disease. There are some researchers who think that phenylalanine may be interfering with the absorption of levodopa.

• Selegiline -- L-phenylalanine along with the selective MAO inhibitor selegiline (Eldepryl, Deprenyl) may boos the antidepressant effects of phenylalanine but they should not be taken together.

• Antipsychotic or neuroleptic drugs -- L-phenylalanine may worsen the symptoms of tardive dyskinesia, a common side effect of these neuroleptic drugs. Some example of these drugs include phenytoin (Dilantin), valproid acid (Depakene, Depakote), and carbamazepine (Tegretol), among others.