Fact Sheet: Cobalamin (Vitamin B12)

Written by Institute for Natural Medicine Staff

Medically Reviewed by Michelle Simon, PhD, ND

Published December 3, 2024
Last Updated December 3, 2024

Overview

B12, a water-soluble vitamin, plays a vital role in nervous system health, red blood cell formation, and DNA synthesis. Since the body doesn’t store it, regular replenishment through food or supplements is essential—especially for people who eat a plant-based diet.¹

Uses

B12 treats pernicious anemia, an autoimmune condition hindering absorption, and helps prevent megaloblastic anemia, characterized by oversized red blood cells that don’t function efficiently.² It also helps maintain the myelin sheath, a protective covering around nerves.

Often prescribed to treat fatigue associated with megaloblastic anemia or adrenal insufficiency, B12 is also used for mood disorders and hormone balance.

The body’s conversion of carbohydrates to glucose—an important energy source for muscles—requires B12.³ It’s needed for neurotransmitter signaling that aids muscle function.⁴

Find a Naturopathic Doctor

Experience the benefits of personalized natural healthcare with a trusted, licensed naturopathic doctor in your area.

Find an ND

Benefits

Vitamin B12 may boost bone health, sharpen cognitive function, and lower cardiovascular risks when paired with folate and B6.⁵Regular intake supports everyday wellness in six crucial ways:

Promotes red blood cell formation. B12 is necessary for the production of healthy red blood cells. A deficiency can lead to megaloblastic anemia, resulting in weakness and fatigue.
Maintains nerve health. Proper nerve function depends on B12, and low levels can lead to “paresthesia,” with tingling and numbness in hands, arms, legs, or feet. Severe and prolonged low levels of B12 may cause nerve damage.
Aids in DNA synthesis. B12 contributes to the production of DNA—genetic material found in all cells. This function is especially critical when cells grow and divide rapidly.
Enhances brain health. Adequate levels of B12 help regulate neurotransmitters for better cognitive function and reduce the risk of neurodegenerative conditions like dementia.
Boosts energy levels. Although B12 doesn’t directly produce energy, it helps the body metabolize fats and carbohydrates and has a key role in converting food into energy.
Supports the heart. B12 helps reduce homocysteine, an amino acid. In high amounts, homocysteine is linked to an increased risk of heart disease. Vitamins B12, B6, and folate help break down homocysteine and convert it into other essential chemicals.

Deficiency

Technician holds test tube of vitamin B12 blood test

Low B12 is one of the most common vitamin deficiencies, with insufficient levels affecting up to 40 percent of the population.⁶

Vegans, vegetarians, and older adults are more susceptible to inadequate B12 levels. Stomach acid production lessens with age, making absorption more difficult. Without enough B12, there’s a risk of anemia, neurologic disorders such as dementia and neuropathy, and hyperhomocysteinemia, which is associated with heart disease, osteoporosis, depression, and cognitive decline.

Ten conditions and factors contribute to vitamin B12 deficiency:⁷

Celiac or Crohn’s disease
Atrophic gastritis
Ongoing use of acid-reducing medication
Long-term metformin use (for type 2 diabetes)
Partial or total gastrectomy
Small intestinal bacterial overgrowth (SIBO)
Pancreatic insufficiency
Helicobacter pylori (H. pylori) infection
Lower stomach acid production, a natural change with aging
Smoking (nicotine blocks absorption)

Recommended Dietary Allowances (RDA)

Age/Status	RDA¹
Birth to 6 months	0.4 mcg
7–12 months	0.5 mcg
1–3 years	0.9 mcg
4–8 years	1.2 mcg
9–13 years	1.8 mcg
14+ years	2.4 mcg
Pregnant	2.6 mcg
Lactating	2.8 mcg

Side Effects

Taken orally, vitamin B12 is considered safe, even in larger doses.¹ Vitamin B12 injections can cause diarrhea and more serious side effects, such as confusion, shortness of breath, dizziness, and difficulty breathing or swallowing.⁸

Interactions

Many medications interfere with vitamin B12 absorption,⁹ including anticonvulsants and acid reducers like proton pump inhibitors and H2 blockers.

Vitamin B12 should not be taken with tetracycline antibiotics because it may affect the medicine’s absorption and efficacy.⁹

Food Sources

Animal sources of B12 include meat, poultry, fish, eggs, and dairy products.¹ Nutritional yeast and some breakfast cereals also provide B12, but plant-based foods naturally lack the vitamin, which is why vegetarians and vegans often need supplementation.

Footnotes

1
Niklewicz A, Smith AD, Smith A, et al. The importance of vitamin B12 for individuals choosing plant-based diets. Eur J Nutr. 2023;62:1551-1559. https://link.springer.com/article/10.1007/s00394-022-03025-4
2
Turner J, Parsi M, Badireddy M. Anemia. StatPearls;2023;Aug 8. https://www.ncbi.nlm.nih.gov/books/NBK499994/?report=reader#_NBK499994_pubdet_
3
Tardy AL, Pouteau E, Marquez D, Yilmaz C, Scholey A. Vitamins and minerals for energy, fatigue and cognition: a narrative review of the biochemical and clinical evidence. Nutrients. 2020 Jan 16;12(1):228. https://doi.org/10.3390/nu12010228
4
O’Leary F, Samman S. Vitamin B12 in health and disease. Nutrients. 2010 Mar;2(3):299-316. https://doi.org/10.3390/nu2030299. Epub 2010 Mar 5
5
Miao Y, Guo Y, Chen Y, et al. The effect of B-vitamins on the prevention and treatment of cardiovascular diseases: a systematic review and meta-analysis. Nutr Rev. 2023. https://pubmed.ncbi.nlm.nih.gov/37850302
6
Spence JD. Metabolic vitamin B12 deficiency: a missed opportunity to prevent dementia and stroke. Nutr Res. 2016 Feb;36(2):109-16. https://doi.org/10.1016/j.nutres.2015.10.003
7
Amin A, Gupta V. Vitamin B12 (cobalamin). StatPearls. 2023;July 16. https://www.ncbi.nlm.nih.gov/books/NBK559132/?report=reader#_NBK559132_pubdet_
8
NIH National Library of Medicine. Cyanocobalamin injection. MedlinePlus. https://medlineplus.gov/druginfo/meds/a605007.html
9
A.D.A.M. Possible interactions with vitamin B12 (cobalamin). https://www.stlukes-stl.com/health-content/medicine/33/000987.htm

This article is provided by

The Institute for Natural Medicine, a non-profit 501(c)(3) organization. INM’s mission is to transform health care in the United States by increasing public awareness of natural medicine and access to naturopathic doctors. Naturopathic medicine, with its person-centered principles and practices, has the potential to reverse the tide of chronic illness overwhelming healthcare systems and to empower people to achieve and maintain optimal lifelong health. INM strives to fulfil this mission through the following initiatives:

Education – Reveal the unique benefits and outcomes of evidence-based natural medicine
Access – Connect patients to licensed naturopathic doctors
Research – Expand quality research on this complex and comprehensive system of medicine

About The Author(s)

Writer

Institute for Natural Medicine Staff

Our dedicated content team of professional staff writers represents decades of experience covering essential natural health topics in an accessible, evidence-based, and engaging way. Guided by a shared passion for holistic well-being, each and every one of our writers strives to empower our readers to take charge of their health.

Supported by a rigorous fact-checking and medical editing process from licensed naturopathic doctors that examines the latest in peer-reviewed research, our team brings their in-depth knowledge of natural health practices into every piece of content we produce. We strive to be the gold standard for evidence-based natural medicine, providing trustworthy information and inspiring narratives to help you live your best health, naturally.

Explore Fact Sheet Articles

Explore