Many medications for common mental disorders, although helpful, can cause unpleasant side effects that discourage patients from taking their prescribed dose. In recent years, there has been a great deal of interest in natural substances to treat the symptoms of depression, anxiety and PMS, either to enhance the effects of prescription drugs or to use alone.

Studies show that a lack of certain nutrients may contribute to the development of mental disorders. Notably, essential vitamins, minerals, and omega-3 fatty acids are often deficient in the general population in America and other developed countries, and are exceptionally deficient in patients suffering from mental disorders.

Many experts believe that nutrition has the potential to affect the symptoms and severity of depression. Supplements including omega-3 fatty acids, vitamins C and E, and folate have been investigated.

Omega-3 fatty acids such as eicosapentaeoic acid (EPA) and docosahexaenoic acid (DHA) might have an impact on depression because these compounds are widespread in the brain. The evidence is not fully conclusive, but omega-3 supplements are an option. One to two grams of omega-3 fatty acids daily is the generally accepted dose for healthy individuals, but for patients with mental disorders, up to three grams has been shown to be safe and effective.

Supplements that contain amino acids have been found to reduce symptoms, possibly because they are converted to neurotransmitters in the brain that help alleviate depression. For example, serotonin is made using the amino acid tryptophan. Dietary supplements that contain tyrosine or phenylalanine, later converted into dopamine and norepinephrine, are also available.

Deficiencies of magnesium and the B vitamin folate have been linked to depression. Trials suggest that patients treated with 0.8mg of folic acid per day or 0.4mg of vitamin B12 per day will have reduced depression symptoms. Patients treated with 125 to 300mg of magnesium with each meal and at bedtime have shown rapid recovery from major depression.

Experts have looked at a range of herbal remedies and supplements for individuals with anxiety. The evidence supports the effectiveness of kava for mild to moderate anxiety disorders. Kava does, however, impact on other medicines metabolized by the liver.

St John’s wort, valerian, Sympathyl (a mixture of California poppy, hawthorn and elemental magnesium) and passionflower have been investigated for anxiety but the studies have generally been small or inconsistent. Lower than average omega-3 levels have been reported in patients with anxiety, and supplementation with omega-3s appears to improve some symptoms. Zinc and chromium supplements may be helpful, as well as calcium and vitamin B6.

Trials of women with premenstrual syndrome (PMS) suggest that vitamin B6 “relieves overall premenstrual and depressive premenstrual symptoms.” Dietary studies also indicate that calcium taken at 1,200mg per day may be useful.

Four hundred IU per day of vitamin E has shown some effectiveness, and several other supplements are under investigation. These include magnesium, manganese and tryptophan.

Calcium supplementation is another promising option. Fluctuations in calcium levels may help explain some features of PMS. Tiredness, appetite changes, and depressive symptoms were significantly improved in one study of women receiving calcium, compared with placebo.

People with obsessive compulsive disorder (OCD) often benefit from selective serotonin reuptake inhibitors (SSRIs), so the nutrients that increase serotonin levels are likely to reduce symptoms. Again, the amino acid tryptophan is a precursor to serotonin, and tryptophan supplements can increase serotonin levels and treat OCD.

St. John’s Wort has also been shown to benefit OCD symptoms. A dose of 900mg per day of St. John’s Wort has been found to improve OCD symptoms and is less likely to cause side effects, but it can interfere with some prescription medicines.

Dr. Shaheen E. Lakhan of the Global Neuroscience Initiative Foundation in Los Angeles says, “There is tremendous resistance from clinicians to using supplements as treatments, mostly due to their lack of knowledge on the subject. Others rather use prescription drugs that the drug companies and the FDA researches, monitors and recalls if necessary.


Dr. Lakhan believes that psychiatrists should be aware of nutritional therapies, appropriate doses, and possible side effects in order to provide alternative and complementary treatments for their patients. “This may reduce the number of noncompliant patients suffering from mental disorders that choose not to take their prescribed medications,” he adds.


Lakhan, S. E. and Vieira, K. F. Nutritional therapies for mental disorders. Nutrition Journal, published online January 21, 2008.

Saeed, S. A., Bloch, R. M. and Antonacci, D. J. Herbal and dietary supplements for treatment of anxiety disorders. American Family Physician, Vol. 76, August 2007, pp. 549-56.

Wyatt, K., Dimmock, P. and Jones, P. Poor-quality studies suggest that vitamin B(6) use is beneficial in premenstrual syndrome. The Western Journal of Medicine, Vol. 172, April 2000, p. 245.