Vitamin B12 Deficiency

What is vitamin B12 deficiency?

Vitamin B12 deficiency happens when your body is either not getting enough or not absorbing enough vitamin B12 from the food that you eat that it needs to function properly. Vitamin B12 is an important nutrient that helps your body make red blood cells and DNA, the genetic material in all of your cells.

Untreated, vitamin B12 deficiency can cause physical, neurological and psychological problems.

What is vitamin B12?

Vitamin B12 is an important nutrient that helps your body keep your nerve cells and blood cells healthy. It also helps your body make DNA, the genetic material in all of your cells. Your body doesn't make vitamin B12 on its own. You have to consume food and drinks that have vitamin B12 in order to get it. Vitamin B12 is found in animal products you eat and drink, like meat, dairy and eggs. It can also be found in fortified foods (foods that have certain vitamins and nutrients added to them) such as certain cereals, bread and nutritional yeast.

Adults need around 2.4 micrograms (mcg) of vitamin B12 a day, and people who are pregnant or breastfeeding need more. The amount of vitamin B12 babies and children need varies based on age.

How does my body absorb vitamin B12?

Two things need to happen for your body to absorb vitamin B12 from the food you eat.

1. Hydrochloric acid in your stomach removes vitamin B12 from the food it was in.
2. Vitamin B12 combines with something called intrinsic factor, a protein made by your stomach.

Vitamin B12 is then able to be absorbed by your digestive system.

What is vitamin B12 deficiency anemia?

Vitamin B12 deficiency anemia happens when your body doesn't have enough healthy red blood cells because your have a vitamin B12 deficiency. Vitamin B12 is needed to make red blood cells. Because of this, a lack of vitamin B12 can cause anemia. People can have a vitamin B12 deficiency without having anemia.

Who does vitamin B12 deficiency affect?

Any person can develop vitamin B12 deficiency at any age. People who are 60 years old or older are more likely to have vitamin B12 deficiency compared to other age groups.

How common is vitamin B12 deficiency?

Approximately 1.5% to 15% of people have vitamin B12 deficiency. Here are the percentages of people who have vitamin B12 deficiency based on age ranges:

• At least 3% of people aged 20 to 39 years old.
• At least 4% of people aged 40 to 59 years old.
• At least 6% of people who are 60 years or over.

What causes vitamin B12 deficiency?

Vitamin B12 deficiency happens if you aren't eating enough vitamin B12 or your body isn't absorbing the vitamin B12 you consume properly. Situations or conditions that can cause vitamin B12 deficiency include:

• Lack of vitamin B12 in your diet: People who don't eat enough foods that naturally have vitamin B12 or don't eat foods fortified with vitamin B12 can develop vitamin B12 deficiency.
• Gastritis: Gastritis is inflammation of the stomach lining, and it’s a common cause of vitamin B12 deficiency. It can cause vitamin B12 deficiency due to a lack of hydrochloric acid in your stomach, which is needed for vitamin B12 absorption.
• Pernicious anemia: People who have pernicious anemia — a rare medical condition — aren't able to make intrinsic factor, a protein made by your stomach. You need intrinsic factor so that your body can absorb B12 vitamin. People with pernicious anemia have a B12 vitamin deficiency.
• Digestive diseases: Diseases that affect the digestive system, like Crohn’s disease and celiac disease, can prevent your body from fully absorbing vitamin B12.
• Surgery: People who have gastrointestinal surgery — like a gastric bypass (weight loss surgery) — can have difficulty absorbing vitamin B12.
• Alcohol use disorder: This condition can damage your digestive system and cause vitamin B12 deficiency.
• Transcobalamin II deficiency: This is a rare genetic disorder that impairs the transport of vitamin B12 (also known as cobalamin) within the body.

What are the symptoms of vitamin B12 deficiency?

Vitamin B12 deficiency can cause physical, neurological and psychological symptoms. The symptoms of vitamin B12 deficiency can develop slowly and can get worse over time. Some people may have no symptoms despite having a low level of vitamin B12 in their bodies. People with vitamin B12 deficiency can have neurological symptoms and/or damage without anemia (lack of red blood cells).

General physical symptoms of vitamin B12 deficiency can include:

• Feeling very tired or weak.
• Experiencing nausea, vomiting or diarrhea.
• Not feeling as hungry as usual.
• Weight loss.
• Having a sore mouth or tongue.
• Having yellowish skin.

Neurological symptoms of vitamin B12 deficiency can include:

• Numbness or tingling in your hands and feet.
• Vision problems.
• Having a hard time remembering things or getting confused easily.
• Having a difficult time walking or speaking like you usually do.

Psychological symptoms of vitamin B12 deficiency can include:

• Feeling depressed.
• Feeling irritable.
• Experiencing a change in the way you feel and behave.

How is vitamin B12 deficiency diagnosed?

It can be difficult to diagnose vitamin B12 deficiency because symptoms aren't always present or they can be similar to other nutritional deficiencies. Healthcare providers will usually do routine blood tests to check for vitamin B12 deficiency in people who have a high risk of developing it.

The tests used to diagnose vitamin B12 deficiency are a complete blood count (CBC) and a vitamin B12 blood test level. A person is diagnosed with vitamin B12 deficiency if the amount of vitamin B12 in their blood is less than 150 per mL.

How is vitamin B12 deficiency treated?

Vitamin B12 deficiency can be treated with vitamin B12. It's often treated with cyanocobalamin, a human-made form of vitamin B12. Depending on the cause of the deficiency, you may only need treatment until your vitamin B12 levels are back to normal, or you may need vitamin B12 therapy for the rest of your life. Options for vitamin B12 treatment include:

• Vitamin B12 oral medication.
• Vitamin B12 intramuscular injections (a shot that goes into your muscle).
• Vitamin B12 nasal gel.
• Vitamin B12 nasal spray.

What are the risk factors for vitamin B12 deficiency?

A person is more likely to develop vitamin B12 deficiency if they have one or more of the following risk factors:

• Being older than 75 years: People over 75 are more at risk for developing vitamin B12 deficiency because their bodies are often unable to fully absorb vitamin B12.
• Having a digestive system disorder: Digestive disorders, like celiac disease and Crohn’s disease, can make it more difficult for your body to absorb vitamin B12.
• Following a strict vegan or vegetarian diet: Vitamin B12 is only naturally found in animal products, like meat and dairy. Because of this, people who eat a vegan or vegetarian diet are more likely to have a vitamin B12 deficiency if they aren't eating enough fortified foods with vitamin B12.
• Taking certain medications: Certain medications can cause low levels of vitamin B12 in your body, including metformin (a drug used to manage diabetes), proton pump inhibitors (PPIs are used to treat GERD and peptic ulcers), histamine H2 blockers (a medicine used to reduce the amount of acid your stomach makes) and oral birth control pills (oral contraceptives).
• Having Sjögren's syndrome. People with Sjögren's syndrome are over six times more likely to have vitamin B12 deficiency.
• Drinking excessive amounts of alcohol: Chronic alcoholism can damage your digestive system and cause vitamin B12 deficiency.

How can I prevent vitamin B12 deficiency?

Most people can prevent vitamin B12 deficiency by consuming foods and drinks that have vitamin B12.

Options for consuming vitamin B12 include:

• Animal food products: Red meat, fish, poultry, eggs, milk and other dairy products all contain vitamin B12.
• Fortified foods: Fortified foods are foods that have certain vitamins and nutrients added to them that they don’t naturally have. Fortified foods include certain breakfast cereals, nutritional yeast, plant milk and certain bread. Be sure to check the food label (nutritional facts) to see if the food has been fortified with vitamin B12.
• Vitamin B12 dietary supplements: Many multivitamins have vitamin B12. There are also supplements that only have vitamin B12. Ask your healthcare provider or pharmacist to help you choose which supplement is best for you.

Other things you can do to help prevent vitamin B12 deficiency include:

• Avoid alcohol: Frequent alcohol consumption can damage your digestive system and make it difficult for your body to absorb vitamin B12.
• Do your best to manage your digestive disease: If you have a digestive disease such as Crohn’s disease or celiac disease, be sure to follow your healthcare provider’s instructions to stay healthy.

What is the prognosis (outlook) for vitamin B12 deficiency?

The prognosis for people with vitamin B12 deficiency depends on how early the deficiency is diagnosed and treated. If the vitamin B12 deficiency is caught early, most symptoms improve with treatment. Depending on the cause of your vitamin B12 deficiency, you may have to only take medication for a short amount of time, or you may have to take medication for the rest of your life.

If vitamin B12 deficiency is left untreated, it can cause lasting side effects that affect the nervous system and brain. More severe side effects of vitamin B12 deficiency include:

• Peripheral neuropathy.
• Degeneration of the spinal cord.
• Paralysis.
• Bowel incontinence and/or urinary incontinence.
• Erectile dysfunction.
• Depression.
• Paranoia and delusions.
• Memory loss.

When should I see my healthcare provider?

If you experience symptoms of vitamin B12 deficiency or are at risk for developing vitamin B12 deficiency, contact your healthcare provider to see if you should take a blood test to measure your vitamin B12 level. If you have already been diagnosed with vitamin B12 deficiency and are experiencing new or concerning symptoms, be sure to reach out to your healthcare provider.

A note from Cleveland Clinic

Vitamin B12 is an important vitamin that your body needs to be healthy. Most people can prevent vitamin B12 deficiency by consuming enough of it in their diet. If you have risk factors for developing vitamin B12 deficiency or are experiencing symptoms, be sure to contact your doctor to get a blood test to check your levels.