What is vitamin B12?

Vitamin B₁₂ is an important vitamin that you usually get from your food. It is mainly found in meat and dairy products. Vitamin B₁₂ helps make red blood cells and keeps your nervous system working right.

What happens if my vitamin B12 level is low?

If you have a very low vitamin B₁₂ level, you might get anemia, depression, dementia, or a serious problem with your nervous system.

You might not have any symptoms if your vitamin B₁₂ level is just a little bit low.

Some people with low vitamin B₁₂ also have high levels of homocysteine (say this: homo-sis-teen), an amino acid in the blood. If you have both of these problems, you may have a higher risk of heart disease and stroke.

How does my doctor know I have a low vitamin B12 level?

Your doctor may check your blood to see if your vitamin B₁₂ level is low. If your vitamin B₁₂ level is close to low, and you have symptoms, your doctor may also check your blood to find out why your vitamin B₁₂ level is low.

I eat meat and dairy products, so why do I have low vitamin B12?

Vegetarians who do not eat meat or dairy products are at risk for low vitamin B₁₂, usually about two years after they become vegetarians. However, most people who have low vitamin B₁₂ are not strict vegetarians. Most people with low vitamin B₁₂ levels have trouble absorbing vitamin B₁₂ from their stomach or small intestines.

What causes problems with absorbing vitamin B12?

Here are some reasons you might have trouble absorbing vitamin B₁₂:

• A disease called pernicious anemia (say this: per-nish-us ah-nee-mee-ah) could destroy the cells in your stomach that help you absorb vitamin B₁₂.

• If you use medicine for heartburn and ulcers for a long time, you may begin to have trouble absorbing vitamin B₁₂.

• If you have had surgery on your stomach or your intestines, you may have trouble absorbing vitamin B₁₂.

Your doctor will be able to find out why you have a low vitamin B₁₂ level by asking questions about your health, giving you a physical exam, and checking your blood, if necessary.

I have just been told I have a low vitamin B12 level. To raise it, can't I just take one multivitamin pill every day?

No. To raise your vitamin B₁₂ level, you have to take at least 1,000 mcg of vitamin B₁₂ every day. Over-the-counter multivitamins do not have this much vitamin B₁₂. To get enough vitamin B₁₂, you will need to take special vitamin B₁₂ pills.

You can also get shots of vitamin B₁₂. Usually, these shots are given every 1 to 2 days for about two weeks. After this, a shot is given once every month. Your doctor can help you decide what is the best treatment for you.

I have been getting a vitamin B12 shot every month for years. Can I change to a pill?

Possibly. In recent years we have found out that in most people, vitamin B₁₂ pills work as well as shots. Ask your doctor if changing to pills would be OK for you.

How long do I have to take the pills or get the shots?

Most people with low vitamin B₁₂ take the pills or get the shots for the rest of their lives.

Where can I get more information about vitamin B12 deficiency?

National Institutes of Health (Facts About Dietary Supplements)

• Web address:www.cc.nih.gov/ccc/supplements/vitb12.html

American Heart Association (for information about homocysteine and heart disease)

• Web address:www.americanheart.org