Cobalamin deficiency: how to fix it

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Linnea Zielinski 

Yael Cooperman, MD - Contributor Avatar

Reviewed by Yael Cooperman, MD, Ro, 

Written by Linnea Zielinski 

last updated: Sep 02, 2021

3 min read

Cobalamin and vitamin B12 are actually the same thing. Cobalamin is an essential vitamin found in animal-based foods like red meat, poultry, fish, dairy products, and eggs.

For that reason, many people mistakenly assume only vegans and vegetarians are prone to a cobalamin deficiency.

Between 73-86% of people in the United States get enough vitamin B12 from diet alone, but millions are at risk for developing a deficiency if they don’t have access or are unable to follow a healthy diet (USDA, 2021).

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Causes of cobalamin deficiency

Not eating animal products can cause a cobalamin deficiency, but that’s not the only cause. 

But getting lots of vitamin B12 from your diet isn’t always enough to raise your levels. Our stomachs contain a substance called intrinsic factor, which helps us absorb vitamin B12. Low levels of intrinsic factor (IF) can be caused by an autoimmune disease, or by bariatric surgeries like gastric bypass. 

Cobalamin deficiency symptoms

Vitamin B12 deficiencies commonly cause a form of anemia called megaloblastic anemia, which is characterized by large, misshapen red blood cells.

Because red blood cells are responsible for carrying oxygen around your body, megaloblastic anemia can cause fatigue and other symptoms. It also can affect red blood cell formation and the nervous system. 

Here are common signs of a cobalamin deficiency:

  • Jaundice (yellowing of the eyes and skin) 

  • Fatigue

  • Swollen, painful tongue

  • Weight loss

  • Tingling in the hands or feet 

  • Impaired coordination 

  • Memory problems 

Severe cobalamin deficiency, which is rare in the United States, can have more severe side effects like confusion, irritability, insomnia, difficulty walking, and even personality changes. 

Why is cobalamin important?

Getting enough of this vitamin is essential for keeping your nerves and blood cells healthy.

Your cobalamin levels dropping low enough to cause a deficiency isn’t something that happens overnight. Our bodies store excess cobalamin in our liver to use when dietary sources are scarce, so it takes some time to really deplete B12 from the body.

Getting enough cobalamin is also vital for fertility and child development. Those pregnant and breastfeeding who don’t get enough of this vitamin may have children with developmental delays, anemia, and disabilities of the brain and spine (NIH, 2021).

While vitamin B12 is important, there are no proven benefits to taking a supplement if your levels are in the normal range. If you’re concerned you may have a cobalamin deficiency, get your blood levels checked by a healthcare provider who can help decide if you need supplements.

Ways to boost your vitamin B12

If you have a cobalamin deficiency, you want to boost your serum levels to a healthy range.

Supplementation can come in the form of an injection or tablet. Shots may be the only option for certain people deficient in cobalamin. Oral B12 has to go through your digestive system, while B12 injections do not.

For people with low levels of intrinsic factor in their stomach, an injection is often a better option.

Diet and supplements

When it comes to maintaining healthy levels of B12, your best bet is to get it from your diet.

Many animal products naturally contain vitamin B12, including red meat, fish, poultry, eggs, and dairy. You can also supplement your diet with foods fortified with B12 like cereal and nutritional yeast.

If you follow a vegan diet or cannot eat any of these alternatives, you’re not out of luck. There are lots of B12 supplements on the market to choose from that don’t contain animal products. 

If you opt for dietary supplements, buy from a brand you trust. The U.S. Food and Drug Administration (FDA) doesn’t regulate supplements, so the quality can differ from brand to brand. 


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

September 02, 2021

Written by

Linnea Zielinski

Fact checked by

Yael Cooperman, MD

About the medical reviewer

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.