Vitamin B12 Supplementation Guidelines

Indications for Supplementation

Dietary insufficiency is an indication for vitamin B12 supplementation, according to the Annals of Internal Medicine 1

For general supplementation without documented deficiency, a standard multivitamin containing approximately 100% of the Daily Value is reasonable, as suggested by the American Academy of Family Physicians 2 and the American College of Physicians 3
The American Cancer Society advises caution with high-dose vitamin supplements during active chemotherapy, but vitamin B12 is not classified as an antioxidant vitamin, as noted by the European Society for Medical Oncology 4

The American Heart Association and other organizations imply that prioritizing dietary sources of B12, such as meat, fish, dairy, and fortified foods, over supplements is recommended when possible, as supported by the Annals of Internal Medicine 2 and the American Academy of Family Physicians 3
Avoiding beta-carotene supplementation, particularly in smokers, is advised due to increased lung cancer incidence and all-cause mortality, as reported by the Annals of Internal Medicine 2 and the American Academy of Family Physicians 3