Health Benefits of Vitamin B12

Medically Reviewed by Poonam Sachdev on September 21, 2022
2 min read

Vitamin B12 is an essential nutrient that helps the body create DNA, nourishes the brain and nervous system, and assists with the formation of healthy red blood cells. The nutrient occurs naturally in meat, fish, and dairy products, and can be created in a laboratory.

Some people lack a protein that helps the body absorb vitamin B12 from foods and supplements. A lack of B12 can put you at higher risk for a specific type of anemia that makes you feel weak and tired. 

Depression Prevention and Treatment

Vitamin B12 plays a role in serotonin production, so a deficiency may be connected with clinical depression. In one study, disabled older women with a B12 deficiency were found to have double the risk of severe depression as those without a deficiency.

In addition, high levels of vitamin B12 have been associated with better chances of recovery from major depressive disorder.

Reduced Risk of Macular Degeneration

Supplementing with vitamin B12 is believed to lower homocysteine in the bloodstream, which may help prevent age-related macular degeneration, an eye disease that can cause blindness in older adults. In one study of 5,000 women age 40 and up, those who took supplements of vitamins B12, B6, and folic acid had 34% fewer cases of macular degeneration after seven years than a placebo group. Their risk of severe degeneration was 41% lower.

Pregnancy Health

If a woman has a vitamin B12 deficiency in the early stages of pregnancy, her child is at an increased risk of neural tube birth defects and low birthweight. Mothers with low B12 levels are also more likely to miscarry or give birth prematurely.

Women with low levels of vitamin B12 are three times more likely to have a child with birth defects.

Brain Health

Vitamin B12 is an essential nutrient for the neurons in the brain. Brain atrophy, which refers to the loss of neurons in the brain, is associated with memory loss and dementia. 

In one randomized trial, older adults with early-stage dementia who were given vitamin B12 supplements to lower their blood homocysteine levels demonstrated a slower rate of cognitive and clinical decline.

Another study found that low B12 levels, even within the normal range, contribute to poor memory performance.

More studies are needed before researchers can be certain of the impact of B12 supplementation on memory loss and dementia. 

There is no known risk of harm associated with vitamin B12. 

However, B12 supplements can interact with medicines, including:

  • Chloramphenicol
  • Proton pump inhibitors
  • Histamine H2 receptor antagonists
  • Metformin

If you are taking any of these medications, talk to your doctor or pharmacist before adding a B12 supplement to your routine.

The recommended daily intake of vitamin B-12 for adults is 2.4 micrograms.

Vitamin B12 is also found in animal products, such as eggs, meat, fish, poultry, milk, and some nutritional yeast products.  Vitamin B12 does not naturally occur in most plant foods, so fortified breakfast cereals are recommended for vegetarians.

Show Sources


American Journal of Clinical Nutrition: Vitamin B-12 concentration, memory performance, and hippocampal structure in patients with mild cognitive impairment.

American Journal of Psychiatry: Vitamin B(12) deficiency and depression in physically disabled older women.

Archives of Internal Medicine: Folic Acid, Vitamin B6, and Vitamin B12 in Combination and Age-related Macular Degeneration in a Randomized Trial of Women.

ESHA Research, Inc., Salem, Oregon.

Food and Nutrition Bulletin: Effects of folate and vitamin B12 deficiencies during pregnancy on fetal, infant, and child development.

Journal of Alzheimer’s Disease: Omega-3 Fatty Acid Status Enhances the Prevention of Cognitive Decline by B Vitamins in Mild Cognitive Impairment.

Mayo Clinic: Vitamin B-12.

National Institutes of Health: Vitamin B12

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