High B12 Level

A high B12 level means you have more vitamin B12 in your blood than expected. Having high B12 levels (also known as hypercobalaminemia) is usually harmless. But if your levels are high because of something other than food or supplements, you might have an underlying medical condition.

Vitamin B12, also known as cobalamin, is an essential vitamin. Not having enough (vitamin B12 deficiency) can cause serious or even permanent health issues. Taking in too much vitamin B12 usually won’t harm you. It takes extremely high doses for this vitamin to cause toxic effects.

How much vitamin B12 is too much?

Your body needs vitamin B12 to work properly, but it only needs tiny amounts. The U.S. National Academies of Sciences, Engineering and Medicine sets the recommended daily amounts of B12 in the U.S. They advise the following amounts:

• Birth to 6 months: 0.4 microgram (mcg)
• 7 months to 12 months: 0.5 mcg
• 1 year to 3 years: 0.9 mcg
• 4 years to 8 years: 1.2 mcg
• 9 years to 13 years: 1.8 mcg
• 14 and older: 2.4 mcg

The official recommendations also increase during pregnancy or while lactating. If you’re pregnant, you should get 2.6 mcg per day. And if you’re lactating, you should get 2.8 mcg per day.

If you aren’t sure how much a microgram is, there are 1 billion micrograms in 1 kilogram (and 1 kilogram is equal to 2.2 pounds).

Symptoms of high B12 levels

High B12 levels can cause the following symptoms:

• Acne or redness affecting your face
• Anxiety
• Chromaturia, which makes your pee look red but isn’t the same as hematuria
• Difficulty sitting or holding still (akathisia)
• Headaches
• Heart palpitations
• High blood pressure (hypertension)
• Insomnia
• Nausea and vomiting

It’s important to remember that these symptoms aren’t common, and it can take an extremely high intake of vitamin B12 to have them. In one case described in 2020, a person didn’t have symptoms until she’d had a total of 15 milligrams (15,000 mcg) of B12 injected over several weeks. Too much B12 by mouth is much less likely to cause symptoms since your body doesn’t absorb excess b12.

High B12 level causes

High B12 levels can happen in two main ways. They are:

• High B12 intake
• Underlying medical conditions that raise b12 levels in your blood

High B12 intake

One common reason people get too much vitamin B12 is that they’re trying to make up for not having enough. B12 deficiency is common, and experts suspect it could affect up to 2 in 5 people worldwide.

Vitamin B12 is in many animal-based foods, and it’s not something you can get enough of from unfortified, plant-based food sources. For example, eating 3 ounces of salmon will get you about 2.7 micrograms of vitamin B12, just over an adult’s RDA (recommended daily allowance).

But your body can’t absorb all the B12 in your food all at once. It gets rid of the excess B12 that it doesn’t absorb through either your poop or your pee. That’s why it’s very difficult to get high B12 levels just from what you eat.

To treat B12 deficiency, healthcare providers commonly prescribe B12 supplements (in pill or oral drop forms). And when oral treatment isn’t enough, B12 injections are an option (but oral treatment is usually adequate).

Underlying medical conditions

Some medical conditions can interfere with how your body processes B12. Those are usually conditions that affect your liver, kidneys or your blood itself. Some examples include:

• Liver disease and liver failure
• Kidney failure
• Cancers, especially blood cancers

Risk factors

The main risk factor for having a high B12 level is needing to take B12 supplements or get treatment with B12 injections. Some reasons why you might need supplements or injection treatments include:

• Age: Vitamin B12 deficiency is more common as you get older, especially after age 65.
• Chronic conditions: Diseases like pernicious anemia or Crohn’s disease can damage your digestive system, making it harder for you to absorb B12 from what you eat.
• Cyanide poisoning: One synthetic form of vitamin B12, hydroxycobalamin, is an antidote for cyanide poisoning. It can be lifesaving for people with severe smoke inhalation after a fire.
• Lack of B12 in your diet: People who follow vegetarian or vegan diets are at risk of developing B12 deficiency. That’s because B12 in food only comes from animal-based sources like meat, dairy, etc.
• Medications and surgery: Several medications can affect how your body processes B12. Examples include proton pump inhibitors (PPIs) for stomach ulcers and diabetes drugs like metformin, to name a few. Weight loss surgeries like gastric bypass can also affect how you absorb B12.

How doctors diagnose high B12 levels

Lab tests, especially blood tests, are the main way that healthcare providers diagnose high B12 levels. Your provider will also likely ask you questions about what you eat, any symptoms you’re having and your health history.

How are high B12 levels treated?

There’s no direct treatment or antidote for high B12 levels from food, supplements or treatments. The only way to treat it is to stop adding B12 and let your body get rid of the excess. However, if your levels are high because of a supplement and you have no symptoms, talk with your healthcare provider. You may be OK to continue that dose.

If you have high B12 levels because of an underlying medical condition, the treatment will mainly depend on that condition. Your healthcare provider is the best source of information about treatment options and what you can expect from them.

What can I expect if I have high B12 levels?

Fortunately, B12 doesn’t cause permanent harmful effects if you have too much of it. Symptoms are rare, though they can be unpleasant. But they’ll go away if you don’t get more B12 than your body can process. And it’s common for people to have high B12 levels with no symptoms.

Can high B12 levels be prevented?

There are a few things you can do to reduce your risk of developing high B12 levels related to B12 intake. They include:

• Get an annual checkup: Checking your vitamin B12 levels is part of routine bloodwork when you have an annual physical with your primary care provider. Early diagnosis may be easier and less likely to overcorrect the levels in your blood.
• Talk to your provider about vitamins and supplements before taking them: Just because they’re available over the counter doesn’t mean they’re automatically safe. You should always talk to your provider about ALL supplements and vitamins before you take them.
• Eat a variety of nutritious foods: Your healthcare provider can give you recommendations on what you should eat and what you may want to avoid.