Vitamin B-12 (cobalamin) is a water-soluble vitamin that plays essential roles in red blood cell formation, cell metabolism, nerve function and the production of DNA.

Research on the use of vitamin B-12 for specific activities and conditions shows:

• Heart and blood vessel disease. Vitamin B-12, in combination with vitamin B-6 and folate (vitamin B-9), has been shown to control high levels of homocysteine in the blood. Elevated homocysteine might increase your risk of diseases of the heart and blood vessels (cardiovascular disease). Despite this benefit, there’s no evidence to show that vitamin B-12 supplements prevent heart disease.
• Dementia. Vitamin B-12 deficiency is associated with dementia and low cognitive function, but it’s not clear whether vitamin B-12 supplements might help prevent or treat dementia.
• Athletic performance. Unless you have a vitamin B-12 deficiency, there’s no evidence that vitamin B-12 supplements will boost your energy or make you a better athlete.