Overview

Vitamin B-12 is a vitamin the body uses to make and support healthy nerve cells. It's also used to make healthy red blood cells and the genetic material inside cells called DNA. Vitamin B-12 also is called cobalamin.

Food sources of vitamin B-12 include poultry, meat, fish and dairy products. Food companies also may add vitamin B-12 to breakfast cereals. Some people may take it as a vitamin by mouth. Healthcare professionals might prescribe vitamin B-12 injectio ns or nasal spray to treat people with very low vitamin B-12 levels.

Having seriously low vitamin B-12 levels, called vitamin B-12 deficiency, isn’t common in the U.S. People who follow a vegetarian or vegan diet can sometimes have low levels. This is because plant foods don't have vitamin B-12.

Older adults and people who have had stomach surgery also are at risk because they may not absorb the vitamin as well. People with digestive conditions such as celiac disease and Crohn's disease also are at risk of low vitamin B-12 levels.

People with very low vitamin B-12 levels can have symptoms such as fatigue, muscle weakness, stomach problems, nerve damage, vision problems and mood changes. They also may have low iron, called anemia, or low blood counts.

The recommended daily amount of vitamin B-12 for adults is 2.4 micrograms (mcg). Older adults may need to eat more vitamin B-12. The ability to absorb vitamin B-12 lowers as a person gets older. Older adults may need to eat 10 to 12 mcg of vitamin B-12 to get enough of this vitamin.