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- Assisting in the production of neurotransmitters, which are chemicals that regulate sleep, pain, and mood
- Enabling proper DNA replication
- Helping catalyze the reaction that produces succinyl-CoA, a chemical required for the synthesis of hemoglobin
- Making red blood cells and preventing anemia
|Age Group (in years)||
Recommended Dietary Allowance
Vitamin B12 Deficiency
- Numbness and tingling of the arms or legs
- Difficulty walking
- Sore tongue
- Loss of appetite
- Memory loss
Vitamin B12 Toxicity
Major Food Sources
- Beef liver
- Tuna fish
- Fortified breakfast cereals
Populations at Risk for Vitamin B12 Deficiency
- People with pernicious anemia—This condition occurs when there is an absence of intrinsic factor. A person who has pernicious anemia will need to be monitored by a physician and take lifelong supplemental vitamin B12.
- Older adults—The incidence of B12 deficiency among the elderly may be as high as 15%. A multivitamin may not contain enough B12 to compensate; talk with your healthcare provider about what your specific needs are for supplementation.
- People with gastrointestinal (GI) disorders—GI disorders, like celiac disease, Crohn's disease, or GI surgery, can lead to malabsorption of B12.
- Strict vegetarians—B12 is not present in any meaningful amounts in plant foods. (Certain blue-green algae do contain B12, but in a form that is not usable). Total vegetarians who consume no animal products may need to supplement with B12. Fortified cereal can be a good source of the vitamin for a vegetarian.
- People who consume excessive amounts of alcohol—Alcoholics tend to have diets lacking in several essential nutrients, including B12.
- People who take strong acid-neutralizing drugs—Those who take medications, like Prilosec, cannot absorb B12 well from food and need to take supplements.
Folate Supplementation May Mask a B12 Deficiency
Tips For Increasing Your Vitamin B12 Intake:
- Rub a little olive oil, squeeze a bit of fresh lemon, and crack some black pepper and salt on a fresh piece of salmon. Grill on the barbeque or broil it in the oven.
- Have a bowl of fortified, high-fiber breakfast cereal in the morning.
- Mix canned tuna with some olive oil, white beans, and salt and pepper. Enjoy with some whole wheat crackers.
- For an afternoon snack, try a cup of yogurt. Jazz it up with some sliced fresh fruit or crunchy granola.
- Skewer large shrimp with mushrooms, tomatoes, onion, and zucchini. Brush on a marinade and toss on the barbecue.
- If you take a multivitamin/mineral supplement, make sure that it contains B12.
Academy of Nutrition and Dietetics http://www.eatright.org/
American Society for Nutrition http://www.nutrition.org/
Centre for Science in the Public Interest http://www.cspinet.org
Health Canada http://www.hc-sc.gc.ca
Andres E, Federici L, Affenberger S, et al. B12 deficiency: a look beyond pernicious anemia [review]. J Fam Pract. 2007;56:537-542.
Groff JL, Gropper S. Advanced Nutrition and Human Metabolism. Belmont, CA: Wadsworth Thomson Learning; 2000.
Vitamin B12. EBSCO Dynamed website. Available at: http://www.ebscohost.com/dynamed. Updated December 14, 2011. Accessed September 19, 2012.
Vitamin B12. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Accessed September 19, 2012.
Vitamin B12. Oregon State Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/infocenter/vitamins/vitaminB12/. Accessed September 19, 2012
Wierzbicki AS. Homocysteine and cardiovascular disease: a review of the evidence. Diab Vasc Dis Res. 2007;4:143-150.
3/6/2013 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Marti-Carvajal AJ, Lathyris D, Salanti G. Homocysteine lowering interventions for preventing cardiovascular events. Cochrane Database Syst Rev. 2013;1:CD006612.
- Reviewer: Brian Randall, MD
- Review Date: 09/2012
- Update Date: 03/06/2013