Many depressed people get a boost from taking extra nutrients, such as tyrosine, tryptophan, methionine, S-adenosylmethionine (SAM-e), DHEA, acetylcarnitine, vitamin C, gamma- and alpha-linolenic acid, calcium, magnesium, lithium and zinc.

Other beneficial supplements include:

* B vitamins, especially B12 and folate. These help to regulate our moods, and deficiencies are common among depressed people (Am J Psychiatry, 2002; 159: 2099-101). Folic acid is especially important (Cochrane Database Syst Rev, 2003; 2: CD003390), and may be low in as many as 30-40 per cent of depressives. If you are taking oral contraceptives, which are known to deplete the body of vitamin B6, consider supplementing. Daily amounts have varied widely in trials; if in doubt, consult a nutritionist.

* The amino acids D,L-phenylalanine (DLPA) and L-phenylalanine (LPA) are converted in the brain to norepinephrine (noradrenaline), a neurotransmitter that is released (and easily depleted) in times of stress. LPA and especially DLPA are also converted into phenylethylamine, a natural mood-lifting substance that is lacking in some people who are depressed. Studies have found success with 75-200 mg/day of LPA, or with 150-200 mg/day of DLPA.

* Eicosapentaenoic acid (EPA), an omega-3 fatty acid that is abundant in fish oil, can relieve the symptoms of depression in those who don’t respond to antidepressant medication (Arch Gen Psychiatry, 2002; 59: 913-9). Try taking 1 g of EPA daily.