Vitamin B12 plays a key role in many aspects of health and may support your eyes, bones, and skin as well as your mind.

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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 function of your nerve cells and is needed for red blood cell formation and DNA synthesis.

For most adults, the recommended dietary allowance (RDA) is 2.4 micrograms (mcg), though it’s higher for people who are pregnant or nursing.

Vitamin B12 supplements may benefit your body and overall health in different ways, from helping your eyes and mind to benefiting your bones, hair, and skin.

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

1. Helps with red blood cell formation and anemia prevention

Vitamin B12 plays a vital role in helping your body produce red blood cells.

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.

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

2. May prevent major birth issues

Adequate vitamin B12 levels are crucial to a healthy pregnancy.

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

One older study found that birthing mothers with vitamin B12 levels lower than 250 milligrams per deciliter (mg/dL) were 2.5–3 times more likely to give birth to a child with birth defects, compared to those with adequate levels. For those with a vitamin B12 deficiency and levels below 150 mg/dL the risk was 5 times higher, compared to those with levels above 400 mg/dL.

3. May support bone health and prevent osteoporosis

Maintaining adequate vitamin B12 levels may support your bone health.

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

This 2021 research also noted a possible link between low vitamin B12 levels and poor bone health and osteoporosis or fracture risk.

In general, clinical research doesn’t support the use of supplemental B vitamins to prevent osteoporotic fractures. More conclusive research is needed.

4. May reduce your risk of macular degeneration

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

This 2022 study points to a link between B vitamins and the risk for macular degeneration, noting that a high dietary intake of these vitamins is associated with lower rates of advanced age-related macular degeneration.

More research is needed to fully understand vitamin B12’s role in promoting vision health and preventing macular degeneration.

5. May improve mood and symptoms of depression

Vitamin B12 may improve your mood.

A 2019 research review noted that B vitamins may help improve moods related to stress, for both healthy people and those more at risk for depressive symptoms.

A 2020 research review analyzing dozens of other studies also noted that even without concrete evidence that B12 specifically affects depression or depressive symptoms, it did find that research points to lower vitamin B12 levels as a higher risk factor for depression.

Yet, other research did not find vitamin B12 supplements were effective for depression aside from those people with advanced neurological conditions.

This is an area that needs more research to determine the exact effects of B vitamins and B12 on mood as well as depressive symptoms.

6. May benefit your brain and memory

Vitamin B12 deficiency has been associated with memory loss, especially in older adults.

One study in people with early-stage dementia showed that vitamin B12 may help slow cognitive decline in certain people, but only those who have higher omega-3 fatty acid levels. Those with lower omega-3 fatty acid levels did not experience any slowing of mental decline.

Another study found that even vitamin B12 levels on the low side of normal can contribute to poor memory performance.

More research with larger numbers of people is needed.

7. May impact your energy levels (if you don’t get enough B12)

Vitamin B12 supplements have long been touted as a go-to product for a surge of energy. But that’s not exactly true, according to the clinical research on this topic.

Sure, all B vitamins play an important role in your body’s energy production, though they don’t necessarily provide energy themselves.

People who experience vitamin B12 deficiency do tend to experience fatigue or a lack of energy, as a common early symptom.

Some research indicates that these people may be able to take vitamin supplements or increase their intake to boost energy levels — but that’s really just addressing the underlying deficiency and lower energy level associated with that.

Clinical research does not show that people can just take B-vitamin or B12 supplements or increase their levels and suddenly get more energy.

Vitamin B12 levels are linked to skin, hair, and nail health, and people who have B12 deficiencies — or sometimes excess levels of this vitamin — can experience complications.

This might include hyperpigmentation, nail discoloration, hair changes, the loss of skin color in patches (vitiligo), and canker sores on the cheek, lips, mouth, and tongue (aphthous stomatitis).

Having adequate levels of vitamin B12 does play a part in your skin, nail, and hair health. However, research doesn’t show that people without a deficiency or excess vitamin B12 would benefit from supplements.

Who is at risk of vitamin B12 deficiency?

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:

  • older adults, most commonly
  • 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

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

Vitamin B12 deficiency can most often be treated by taking supplements, diet changes, B12 injections, and by addressing any underlying medical conditions. Your healthcare team can best diagnose and determine what’s best for you.


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

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