Many common mental disorders are caused by vitamin deficiencies

There is no evidence for this. Problems like depression and anxiety in varying degrees and for various periods are common in the community. Mood disturbance can accompany certain vitamin deficiencies. But there are many other causes of mood disturbance such as interpersonal conflicts, poorly developed mechanisms for coping with unpleasant situations, and inappropriate lifestyles, including lack of exercise and poor sleep habits. It is very uncommon for mood disturbances to be associated with vitamin deficiency in countries where there is an adequate food supply.

If we have not eaten for a while, having food can make us feel better. Scientists do not fully understand why this is. However, current research is examining the role of food components, like amino acids, which can produce neurotransmitters (substances which communicate between nerve cells) in the brain. Vitamins do not appear to play a role here.

As far as major psychotic disorders like schizophrenia and manic-depression are concerned, the idea that large doses of vitamins could be helpful has been disproven by a well-controlled study conducted by Dr Ban and other Canadian psychiatrists.