Tyrosine (actually L-tyrosine) is a precursor of the neurotransmitters norepinephrine and dopamine. Taking tyrosine on an empty stomach may cause an increase in norepinephrine and dopamine in the brain, which can lead to increased energy, alertness and improved moods, thus relieving depression. Unlike Saint-John's-wort, which can take two months to work, and prescription antidepressants, which probably won't kick in for about six weeks, tyrosine works very quickly. However, it can raise blood pressure in some people, so therefore must be used cautiously by people with hypertension.

Another amino acid, phenylalanine, is likewise a precursor of norepinephrine and dopamine that can be used to treat depression (with the same caution about its effects on blood pressure). In the past I've recommended trying a mixture of D-phenylalanine and L-phenylalanine for depression in a combination, known as DLPA. The mixture is less likely to raise blood pressure than the straight L-form and can be used as part of a broader regimen to treat depression. The first thing in the morning (about an hour before breakfast) take 1,500 milligrams of DLPA, 100 milligrams of vitamin B-6, 500 milligrams of vitamin C plus a piece of fruit or small glass of juice. Make sure you're not using any over-the-counter or prescription drugs that can contribute to depression. These include all antihistamines, tranquilizers, sleeping pills and narcotics. If DLPA doesn't help, try L-tyrosine in the same way.

On the whole, I suggest following a low-protein, higher carbohydrate diet to help break out of depression. Be especially careful about alcohol and any recreational drugs including cocaine, amphetamines, “downers,” narcotics and marijuana. Although they may provide a temporary sense of relief, if used regularly, they're likely to increase depression to dangerous levels. Addiction to coffee and others forms of caffeine can also interfere with normal moods and make depression worse. Be sure to get regular, physical exercise – 45 minutes of aerobic activity most days – itself an antidepressant.

Dr Weil, http://www.drweil.com/app/cda/drw_cda.html-command=TodayQA-questionId=3499-pt=Question