What is vitamin B12?

Vitamin B12 is an essential vitamin that helps your nerves, blood, and DNA work properly. Health benefits of vitamin B12 include promotion of heart health, brain function, energy, and other systems.
Vitamin B12 is an essential vitamin that helps your nerves, blood, and DNA work properly. Health benefits of vitamin B12 include promotion of heart health, brain function, energy, and other systems.

Eating a healthy diet helps you get all the vitamin B12 benefits you need, but sometimes, you might also need to take a daily multivitamin.

Vitamin B12 is an essential vitamin that helps your nerves, blood, and DNA work properly. Your body doesn’t ordinarily produce B12, so you need to get it from your diet every day. You can get B12 from animal proteins like meat, fish, eggs, and dairy, and also from fortified foods like cereals and grains. 

B12 binds to proteins in your food and eventually goes to your small intestine, where it gets absorbed. 

Some people are more likely to have low levels of B12, which can cause muscle weakness and tiredness. Taking vitamin B12 benefits your body and can prevent a deficiency. 

Helps make DNA

You need B12 to convert amino acids into compounds that help make DNA. Your DNA is the molecules in your cells that carry your genetic information. Without enough B12, your body can’t process your DNA properly, which can turn genes on or off. These gene changes can raise your risk for cancer and other problems. 

The results of tests correlating B12 and cancer risk are mixed, though. Some studies show that too low levels of B12 lead to some cancers, but other studies show too much B12 can also raise your risk of cancer. More research is necessary. 

Helps nerves function

The role of B12 in amino acid conversion is also important for your nerves. It helps regulate reactions that build your nerves, the protective lining of your nerves, and the neurotransmitters that tell your nerves what to do. A lack of B12 causes nerve damage, numbness, tingling, and muscle weakness. 

Builds red blood cells

Your body uses B12 to make new red blood cells and to produce hemoglobin, which is a protein that carries oxygen in your blood. Without enough B12, your bone marrow doesn’t produce enough red blood cells, and they don’t form properly. They’re too big, and they’re oval-shaped instead of circular, so they die sooner than healthy red blood cells. 

The result is low red blood cell levels and a type of anemia called megaloblastic anemia. Without enough red blood cells, your body can’t carry oxygen to your cells and tissues, and you might feel tired and weak. 

Prevents B12 deficiency 

Certain digestive conditions, surgeries, and medications are more likely to cause low B12, even if you have a healthy diet. These include:

You can prevent a B12 deficiency by taking a daily multivitamin. Most vitamins have about 6 micrograms of B12. 

Might help male infertility

Early research shows that taking B12 supplements might help improve your sperm’s ability to move and raise your sperm count. More studies are necessary to confirm this, though.  

Might promote heart health

Heart disease is linked to high levels of an amino acid called homocysteine. B12 regulates the amount of homocysteine in your blood and helps break it down. 

Studies show that taking B12 supplements can help lower homocysteine levels, which might promote heart health. However, the current studies also show that extra B12 doesn’t change your risk of heart attack and stroke even though it can change your homocysteine levels.

Might help brain function

A lack of B12 can cause memory loss, confusion, seizures, and problems thinking and making decisions. If you have a B12 deficiency, taking a supplement can help your brain function and improve cognitive symptoms. 

Some studies also show that people with Alzheimer’s disease have high homocysteine levels. Experts think these high levels might cause a loss of nerve cells and other problems. 

That said, taking B12 vitamins doesn’t currently appear to improve Alzheimer’s symptoms or other brain disease symptoms, even though it lowers homocysteine levels. 

Might improve energy

Low levels of B12 can cause tiredness and weakness, which is often caused by a lack of red blood cells and oxygen. Taking a daily vitamin can improve your energy levels when you have low B12 levels.

Lots of people claim B12 can help your exercise performance and boost your energy and endurance, but unless you have a diagnosed deficiency, taking B12 vitamins isn’t likely to help. 

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Might support healthy bones

High homocysteine levels can lead to bone breakdown, lower blood flow in your bones, and slower bone building, which can lead to osteoporosis and fractures. B12 regulates homocysteine levels, so experts think B12 could help support healthy bones. 

In a small study, patients who took B12 had better homocysteine levels and fewer bone fractures than the control group. However, other research shows that B12 had no overall effect on fractures even though it lowered homocysteine levels. 

Might help mood

Some studies show that about 30 percent of people hospitalized with depression are low on B12. Other studies show that people with low B12 are twice as likely to have depression compared to those with healthy levels. 

It’s not clear how low B12 leads to depression, but it might be linked to problems with chemical reactions in the brain. Once again, however, the research shows taking vitamin B12 might not help. 

Some studies show it has no effect on depression symptoms, while others show it significantly lowers symptoms. The results are mixed, so more research is necessary. 

Get it from food first

B12 is an essential vitamin, and you need healthy levels for your body to work properly. You can prevent low B12 levels by eating animal proteins or fortified foods or by taking a B12 supplement. 

You might need to take a standard vitamin with B12 to help prevent deficiency from chronic diseases, medications, or if you eat a vegetarian or vegan diet. Keep in mind that some pill forms have high doses, which you don’t always need.

Overall, though, it’s best to look at B12 vitamin pills as a supplement to your diet or for diagnosed B12 deficiency and pernicious anemia, not as a treatment for other conditions. If you’re thinking about taking B12, talk to your doctor and research ways you can potentially get it from your diet, first.  

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Medically Reviewed on 7/27/2022
References
SOURCES:

Al Amin, A S M., Gupta, V., StatPearls, "Vitamin B12 (Cobalamin)," StatPearls Publishing, 2022. Harvard Medical School Harvard Health Publishing: "Vitamin B12 deficiency can be sneaky and harmful."

Harvard T.H. Chan School of Public Health: "Vitamin B12."

Johns Hopkins: "Vitamin B12 Deficiency Anemia."

Mount Sinai: "Vitamin B12 (Cobalamin)."

National Institutes of Health Office of Dietary Supplements: "Vitamin B12 Fact Sheet for Health Professionals."

Oregon State University Linus Pauling Institute: "Vitamin B12."