Vitamin B-12 and other B vitamins play a role in producing brain chemicals that affect mood and other brain functions. Low levels of B-12 and other B vitamins such as vitamin B-6 and folate may be linked to depression.

Low levels of a vitamin can result from eating a poor diet or not being able to absorb the vitamins you consume. Older adults, vegetarians and people with digestive disorders such as celiac disease or Crohn's disease may have trouble getting enough B-12. Sometimes a vitamin B-12 deficiency occurs for unknown reasons. Your doctor may order a blood test to check levels of B-12 or other vitamins if a deficiency is suspected.

If you have a vitamin B-12 deficiency, taking a daily supplement that includes vitamin B-12 may help your body get the nutrients it needs. But study results have been mixed and questionable on whether vitamin B-12 supplements can help reduce the risk of depression. Because B-12 and other vitamin supplements can interact with some medications, especially in high doses, talk to your doctor before you take a vitamin supplement.

The best way to make sure you're getting enough B-12 and other vitamins is to eat a healthy diet that includes sources of essential nutrients. Vitamin B-12 is plentiful in animal products such as fish, lean meat, poultry, eggs, and low-fat and fat-free milk. Fortified breakfast cereals also are a good source of B-12 and other B vitamins.

Keep in mind, the role of B vitamins in depression isn't clear and more research is needed. And no supplement can replace proven depression treatments such as antidepressants and psychological counseling.