Vitamin B12, also known as cobalamin, is an essential vitamin that your body needs but cannot produce.

It’s found naturally in animal products, but also added to certain foods and available as an oral supplement or injection.

Vitamin B12 has many roles in your body. It supports the normal function of your nerve cells and is needed for red blood cell formation and DNA synthesis.

For most adults, the recommended daily intake (RDI) is 2.4 mcg, though it’s higher for women who are pregnant or breastfeeding (1).

Vitamin B12 may benefit your body in impressive ways, such as by boosting your energy, improving your memory and helping prevent heart disease.

Here are 9 health benefits of vitamin B12, all based on science.


Low vitamin B12 levels cause a reduction in red blood cell formation and prevent them from developing properly (2).

Healthy red blood cells are small and round, whereas they become larger and typically oval in cases of vitamin B12 deficiency.

Due to this larger and irregular shape, the red blood cells are unable to move from the bone marrow into the bloodstream at an appropriate rate, causing megaloblastic anemia (2).

When you’re anemic, your body doesn’t have enough red blood cells to transport oxygen to your vital organs. This can cause symptoms like fatigue and weakness.

Summary Vitamin B12 is involved in red blood cell formation. When vitamin B12 levels are too low, the production of red blood cells is altered, causing megaloblastic anemia.

Adequate vitamin B12 levels are crucial to a healthy pregnancy.

Studies show that a fetus’s brain and nervous system require sufficient B12 levels from the mother to develop properly.

Vitamin B12 deficiency in the beginning stages of pregnancy may increase the risk of birth defects, such as neural tube defects. Furthermore, maternal vitamin B12 deficiency may contribute to premature birth or miscarriage (3).

One study found that women with vitamin B12 levels lower than 250 mg/dL were three times more likely to give birth to a child with birth defects, compared to those with adequate levels (4).

For women with a vitamin B12 deficiency and levels below 150 mg/dL the risk was five times higher, compared to women with levels above 400 mg/dL (4).

Summary Appropriate vitamin B12 levels are key to a healthy pregnancy. They’re important for the prevention of brain and spinal cord birth defects.

Maintaining adequate vitamin B12 levels may support your bone health.

One study in more than 2,500 adults showed that people with a vitamin B12 deficiency also had lower than normal bone mineral density (5).

Bones with decreased mineral density can become delicate and fragile over time, leading to an increased risk of osteoporosis.

Other studies have also shown a link between low vitamin B12 levels and poor bone health and osteoporosis, especially in women (6, 7, 8).

Summary Vitamin B12 may play a vital role in your bone health. Low blood levels of this vitamin have been associated with an increased risk of osteoporosis.

Macular degeneration is an eye disease that mainly affects your central vision.

Maintaining adequate levels of vitamin B12 may help prevent the risk of age-related macular degeneration.

Researchers believe that supplementing with vitamin B12 may lower homocysteine, a type of amino acid that is found in your bloodstream.

Elevated homocysteine levels have been associated with an increased risk of age-related macular degeneration (9, 10).

A study involving 5,000 women aged 40 or older concluded that supplementing with vitamin B12, along with folic acid and vitamin B6, may reduce this risk (11).

The group receiving these supplements for seven years had fewer cases of macular degeneration, compared to the placebo group. The risk of developing any form of the condition was 34% lower, while it was 41% lower for more severe types (11).

Ultimately, further studies are needed to fully understand vitamin B12’s role in promoting vision health and preventing macular degeneration.

Summary Maintaining adequate levels of vitamin B12 decreases homocysteine levels in your blood. This may help prevent the development of age-related macular degeneration.

Vitamin B12 may improve your mood.

The effect of vitamin B12 on mood is not yet fully understood. However, this vitamin plays a vital role in synthesizing and metabolizing serotonin, a chemical responsible for regulating mood.

Therefore, vitamin B12 deficiency may lead to decreased serotonin production, which may cause a depressed mood.

Studies support the use of vitamin B12 supplements for improving symptoms of depression in people deficient in this vitamin.

One study in people with depression and low vitamin B12 levels found that those who received both antidepressants and vitamin B12 were more likely to show improved depressive symptoms, compared to those treated with antidepressants alone (12).

Another study discovered that vitamin B12 deficiency was associated with twice the risk of severe depression (13).

Additionally, high vitamin B12 levels have been linked to better treatment outcomes and an increased probability of recovery from major depressive disorder (MDD) (14).

Though vitamin B12 supplements may help improve mood and depression in people with a deficiency, research does not currently suggest that they have the same effect in those with normal B12 levels.

Summary Vitamin B12 is needed for the production of serotonin, a chemical responsible for regulating mood. Vitamin B12 supplements may help improve mood in people with an existing deficiency.



One study in people with early-stage dementia showed that a combination of vitamin B12 and omega-3 fatty acid supplements slowed mental decline (15).

Another study found that even vitamin B12 levels on the low side of normal can contribute to poor memory performance. As a result, supplementing with this vitamin may improve memory, even in the absence of a clinically diagnosed deficiency (16).

More research is needed to make sound conclusions on the effect of vitamin B12 supplements on memory and cognitive function.

Summary Vitamin B12 may help prevent brain atrophy and memory loss. More research is needed to conclude if supplementing with this vitamin can improve memory in those without a deficiency.

Vitamin B12 supplements have long been touted as the go-to product for a surge of energy.

All B vitamins play an important role in your body’s energy production, though they don’t necessarily provide energy themselves (17).

Currently, there is no scientific evidence to suggest that vitamin B12 supplements can boost energy in those with sufficient levels of this vitamin (18).

Since vitamin B12 is water-soluble, your body cannot store extra amounts. Any excess passes through your body and is eliminated when you urinate (1).

On the other hand, if you’re significantly deficient in vitamin B12, taking a supplement or increasing your intake will likely improve your energy level (19).



High blood levels of the common amino acid homocysteine have been linked to an increased risk of heart disease.

If you’re significantly deficient in vitamin B12, your homocysteine levels become elevated.

Studies have shown that vitamin B12 helps decrease homocysteine levels, which may reduce your risk of heart disease (20, 21, 22).

However, there is currently no scientific evidence to confirm that vitamin B12 supplements are effective in this regard (23).

Therefore, further research is needed to understand the relationship between vitamin B12 and heart health.

Summary Vitamin B12 can decrease blood homocysteine, a type of amino acid that is associated with an increased risk of heart disease. However, research does not currently support the claim that vitamin B12 reduces this risk.

Given vitamin B12’s role in cell production, adequate levels of this vitamin are needed to promote healthy hair, skin and nails.

In fact, low vitamin B12 levels can cause various dermatologic symptoms, including hyperpigmentation, nail discoloration, hair changes, vitiligo (the loss of skin color in patches) and angular stomatitis (inflamed and cracked mouth corners) (24, 25).

Supplementing with vitamin B12 has been shown to improve dermatologic symptoms in people with B12 deficiency (26, 27).

However, if you’re well-nourished and not deficient in this vitamin, taking a supplement is unlikely to improve your skin, nail strength or hair health (28).

Summary Healthy vitamin B12 levels are important for your hair, skin and nails. However, taking a supplement probably won’t improve your health in these areas if your levels are already sufficient.

An estimated 6% of people in the US and UK aged 60 or older have vitamin B12 deficiency, while about 20% have low to normal or borderline deficient levels (29).

Vitamin B12 deficiency can occur in one of two ways. Either your diet lacks adequate amounts of it or your body is unable to fully absorb it from the food you eat.

Those at risk of vitamin B12 deficiency include (1):

  • Older adults
  • People with gastrointestinal disorders, such as Crohn’s disease or celiac disease
  • Those who have had gastrointestinal surgeries, such as bariatric surgery or bowel resection surgery
  • People on a strict vegan diet
  • Those who take metformin for blood sugar control
  • Those taking proton pump inhibitors for chronic heartburn

In many older adults, the secretion of hydrochloric acid in the stomach is reduced, causing a reduction in the absorption of vitamin B12.

If your body has difficulty absorbing vitamin B12, your doctor may recommend intramuscular injections of B12 to increase your levels.

Vitamin B12 is only found naturally in animal products.

Even though some plant-based milks or grains may have been fortified with vitamin B12, vegan diets are often limited in this vitamin, putting people at risk of deficiency.

If you eat a healthy, varied diet, preventing a vitamin B12 deficiency should be easy. However, if you think that you might be at risk, speak to your doctor.

Vitamin B12 deficiency can most often be prevented or resolved with oral or intramuscular injections.

Summary Risk factors for vitamin B12 deficiency include a decreased ability to absorb this vitamin due to low hydrochloric acid secretion, certain medications or gastrointestinal disease and surgeries. Vegans are also at risk since B12 is only found in animal products.

Vitamin B12 is a water-soluble vitamin that you must obtain through diet or supplements.

It’s responsible for many bodily functions and may benefit your health in various ways, such as by preventing major birth defects, supporting bone health, improving mood and maintaining healthy skin and hair.

Getting enough vitamin B12 through your diet is crucial. However, if you struggle to obtain enough or have a condition that affects absorption, supplements are a simple way to increase your B12 intake.