Vitamin B-12 and depression: Are they related?

Doctors have long known of the relationship between low levels of vitamin B-12 and depression. Vitamin B-12 and other B vitamins, such as folate, play a role in the production of certain neurotransmitters, which are important in regulating mood and other brain functions.

However, it is less clear whether vitamin B-12 deficiency may be the cause or the result of depression. Poor nutrition is one cause of vitamin B-12 deficiency. But poor nutrition may also be a consequence of depression. People who are depressed may lose interest in eating or make less healthy food choices, which may lead to vitamin B-12 deficiency.

A study published in the American Journal of Psychiatry in December 2002 examined the association between low levels of vitamin B-12 and depression in 3,884 older adults. The study reported that older adults with vitamin B-12 deficiency were more likely to have depressive symptoms than those who were not deficient in vitamin B-12. However, the reason for this isn't clear and more research is needed to confirm this finding.

When talking to your doctor about depression, keep in mind that it's important for him or her to address any underlying physical conditions — such as vitamin B-12 deficiency, thyroid disease or certain types of anemia — that may be contributing to depression. Treatment of these underlying conditions may improve depression. However, if depression persists after successful treatment of the underlying condition, your doctor may recommend treatment that specifically targets your depression, such as antidepressants or psychotherapy.