Feeling sad, or what we call "depressed", happens to all of us. The sensation usually passes after a while. However, a person with a depressive disorder - clinical depression - finds that his state interferes with his daily life. His normal functioning is undermined to such an extent that both he and those who care about him are affected by it.

Depression is also linked to a lack of certain vitamins, especially the B vitamins which are used in nervous system function. A less than adequate intake may produce subtle changes in mood, even before a deficiency could develop. B6 also plays a role in the brain chemical production of serotonin. Studies show that people who are depressed have low levels of B6 and serotonin. Certain drugs, such as hormone replacement therapy, oral contraceptives, and anti-tuberculous medication can interfere with the body's use of B6, creating a borderline deficiency.

Other B vitamins also participate in mental health. Folic acid deficiency can cause personality change and depression. Vitamin B12, at just marginally low levels can contribute to depression and memory problems. Not only is it easily destroyed by cooking, but is most abundant in leafy green vegetables- an often underconsumed food group. As we age, vitamin B12 may not be absorbed as readily, even if the recommended daily requirement is met through the diet.Minerals that play a role in the development or prevention of depression, irritability, and mood swings include calcium, iron, magnesium, selenium, and zinc.