Vitamin B12 is an important nutrient. It helps your body create red blood cells. It also helps keep your nervous system — especially your nerves — healthy. Vitamin B12 helps make the genetic material DNA. And it helps prevent a type of anemia that can make you tired and weak.
If you are like most people, you get enough vitamin B12 through the foods you eat. But as people age, they often have trouble absorbing this vitamin. If that happens, you will need to eat foods with added vitamin B12 or take a vitamin supplement. Vitamin B12 from those sources is easier to absorb.
What foods contain vitamin B12?
Vitamin B12 exists naturally in many foods. Plants have no vitamin B12. Many foods, such as some breakfast cereals, are fortified with vitamin B12.
Other good sources of vitamin B12 include:
- Fish, especially sardines, mollusks, salmon and some crustaceans, such as Alaska king crab
- Meat and poultry, especially organ meats like liver and other giblets
- Eggs, milk and other dairy
To see if vitamin B12 has been added to other foods, check nutrition labels.
How much vitamin B12 do I need?
The recommended amount of vitamin B12 for adults is 2.4 micrograms (mcg) per day. For pregnant women, the amount is slightly higher at 2.6 mcg. Women who breastfeed should have 2.8 mcg each day.
Should I take vitamin B12 supplements?
If you are over 50, you should get most of your vitamin B12 through fortified foods or supplements. Age can diminish the body's ability to use the vitamin B12 that occurs naturally in foods; many older adults do not have enough hydrochloric acid in their stomach to absorb it.
Others who may need supplements include:
- People who have celiac disease or Crohn's disease
- People who have had weight-loss surgery
- People with pernicious anemia, as this condition prevents the absorption of vitamin B12 by destroying certain stomach cells
- Vegetarians and vegans, whose diet may not provide enough of the vitamin
Taking certain heartburn and other medicines also can interfere with the absorption of vitamin B12.
Multivitamin pills will not raise a low vitamin B12 level. You'll need a supplement.
What happens if I don't get enough vitamin B12?
If your B12 level is only a little low, you may not have any symptoms. But a greater deficiency can cause signs of anemia, including fatigue, weakness and paleness. It can cause constipation, weight loss and numbness and tingling of the hands and feet.
Low levels of vitamin B12 can also cause depression, confusion, poor memory, dementia, balance problems and soreness of the mouth.
Because too little vitamin B12 can result in progressive damage to the nervous system, it is vital to get treatment as soon as you can.
Talk to your doctor if you are concerned that you are not getting enough vitamin B12. The doctor may recommend supplements or prescribe vitamin B12 shots or specific doses in oral forms. The vitamin may also be prescribed in the form of a nasal gel.
Created on 03/25/2009
Updated on 02/21/2013
- United States Department of Agriculture. National nutrient database for standard reference. Vitamin B12.
- National Institutes of Health Office of Dietary Supplements. Dietary supplement fact sheet: Vitamin B12.
- United States Department of Agriculture. Dietary guidelines for Americans 2010.
- Familydoctor.org. Vitamin B12.