Vitamin B-12 is an important vitamin that you usually get from your food. It is mainly found in fish, shellfish, meat and dairy products. Vitamin B-12 helps make red blood cells and DNA, and it keeps your nervous system working properly.
Most people with low vitamin B-12 levels either do not consume meat and dairy products or they have trouble absorbing vitamin B-12 from their stomach or small intestines. Vegetarians, vegans (strict vegetarians who do not eat any animal products) and the elderly are at higher risk for not getting enough vitamin B-12.
The following are some things that can cause problems with absorbing vitamin B-12:
Your doctor will find out why you have a low vitamin B-12 level by asking questions about your health, giving you a physical exam and checking your blood. He or she may need to do other tests to check for a low level of vitamin B-12.
You might not have any symptoms if your vitamin B-12 level is just a little bit low. However, a very low vitamin B-12 level can cause symptoms of anemia, such as paleness, weakness and fatigue (severe tiredness). It can also cause depression, dementia and other serious problems with your nervous system. Damage to your nervous system that is caused by a low vitamin B-12 level can become permanent if you don't get treatment promptly.
Some people who have low vitamin B-12 levels also have high levels of homocysteine (say: "hoe-moe-sis-teen"), an amino acid (a building block of protein) in the blood. If you have low vitamin B-12 and high homocysteine, you may have a higher risk of heart disease and stroke.
No. Over-the-counter multivitamins do not contain enough vitamin B-12 to raise a low level. To get enough vitamin B-12, you will need to take special vitamin B-12 pills.
You can also get shots of vitamin B-12. Usually, these shots are given every 1 to 2 days for about 2 weeks. After this, a shot is given once every month. Vitamin B-12 is also available as a prescription nose spray that is used either daily or weekly. This may be an option for patients who have used the shots to raise their vitamin B-12 level. Your doctor can help decide what form of vitamin B-12 is right for you.
Written by familydoctor.org editorial staff