Phenylalanine

Natural Health, Jan, 1999 by Susan Ryan-Vollmar

This essential amino acid fights pain and relieves depression.

WHAT IT IS Phenylalanine is an essential amino acid that plays an important role in mood, memory, and mental alertness.

HEALING CLAIMS Phenylalanine is primarily used to relieve chronic pain and treat depression. It is also said to suppress appetite, increase mental alertness, and boost energy.

HOW IT WORKS Phenylalanine is a molecule consisting of two compounds--D-phenylalanine and L-phenylalanine. D-phenylalanine is credited with pain-relieving properties, and the L form, often used in the treatment of depression, is said to have a stimulating effect.

D-phenylalanine relieves pain by maintaining blood levels of endorphins (naturally produced opiates) and enkephalins (analgesics that also stimulate mental alertness). The body metabolizes L-phenylalanine into tyrosine (a nonessential amino acid). Together, phenylalanine and tyrosine are converted into three neurotransmitters: dopamine, noradrenaline, and adrenaline. These regulate state of mind, mood, and attitude. Low levels of these neurotransmitters have been linked with depression. L-phenylalanine also works with tryptophan (an essential amino acid) to regulate the hormone cholecystokinin (CCK), which sends a feeling of fullness to the brain.

THE EVIDENCE A double-blind study published in a German psychiatry journal showed that phenylalanine was as effective as the antidepressant drug Imipramine. Another study, published in the Journal of Clinical Psychiatry, found that one to four grams of L-phenylalanine (in combination with vitamin [B.sub.6]) elevated mood in 78 percent of participants. And a study published in a French anesthesiology journal found D-phenylalanine effective against chronic pain of cancer patients, completely eliminating the need for analgesics in 78 percent of the test subjects.

However, even though phenylalanine has gained a popular reputation for increasing alertness and energy, there is no clinical evidence to that effect.

DIETARY SOURCES The average diet can provide from 500 to 2,000 mg of phenylalanine per day. Phenylalanine is found in protein-rich foods such as milk, meat, fish, cheese, and soybeans, and also in foods containing aspartame.

HOW MUCH DO I NEED? Most people get plenty of phenylalanine from their diets. Too much can cause anxiety, headaches, insomnia, and high blood pressure. If you choose to supplement, some experts recommend keeping supplemental intake to no more than 3,000 mg a day.

HOW TO TAKE IT For pain relief, the recommended dosage is 1,000 to 2,000 mg a day, although for severe pain, it may initially be necessary to take up to 4,500 mg. Reduce or discontinue supplementation once the pain subsides. If you are depressed, it is important to get professional help. Michael Hirt, M.D., director of the Center for Integrative Medicine in Tarzana, Calif., prescribes 1,500 mg phenylalanine a day to patients complaining of depression and fatigue.

For best results it should be taken on an empty stomach. It can take one to two weeks to get the desired result. Do not take for more than three weeks at a time, as it may interfere with the body's amino-acid balance. Long-term supplementation of phenylalanine and other amino acids can also cause liver and kidney damage.

SAFETY The FDA considers phenylalanine safe, although some people may be sensitive to high doses. The FDA has reported cases of heart palpitations, shortness of breath, headaches, high blood pressure, insomnia, and hyperactivity after taking phenylalanine supplements.

People with PKU disease and people with pigmented skin cancers should avoid phenylalanine. Women who are pregnant or breast-feeding, and people who have high blood pressure should not take it without professional supervision.

From the Source

Fish and other meats are good sources of phenylalanine. But vegetarians can get it from soyfoods and supplements.

Susan Ryan-Vollmar is a writer living in Somerville, Mass.