What You Need to Know About Vitamin B-12

Diet & Fitness: Nutrition : Nutrient Library

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*What does it do?

*How much do you need?

*What are the best food sources?

*What happens if you don’t get enough?

*What happens if you get too much?

*Vitamin B-12-rich recipes on Delish

What does it do?

Vitamin B-12 is a water-soluble B vitamin that helps transform fats and proteins from foods into energy and works with folic acid to produce normal red blood cells. An adequate supply of vitamin B-12is also necessary for normal neurological function.

How much do you need?

The following table lists the recommended intake for healthy people based on current scientific information.

What are the best food sources?

Vitamin B-12 is found naturally in animal-based foods, such as meat, fish, poultry, eggs and dairy foods. Particularly rich sources of vitamin B-12 include shellfish, herring, sardines, trout and some game meats. Vegans and strict vegetarians can get B-12 from some fortified foods, such as ready-to-eat cereals and meal replacements (e.g., bars and drinks).

What happens if you don’t get enough?

Nutritional deficiency of this vitamin is rare among those under 50 years old because the human body can store several years’ worth. However, when it does occur it causes pernicious anemia (also known as megaloblastic anemia), a condition in which the body fails to absorb B12 and becomes unable to produce enough healthy red blood cells. Symptoms include low counts of abnormally large red blood cells, fatigue, nerve damage, numbness and tingling of the extremities (e.g. fingers, toes), cognitive changes, a sore tongue or loss of appetite.

Adults over 50 years old are often at risk of not getting enough vitamin B-12. This may be because of a decrease in the production of stomach acid with age (which is needed to extract B-12 from food) or malabsorption problems due to the presence of atrophic gastritis (a chronic inflammation that causes damage to the lining of the stomach and results in the body’s inability to extract vitamin B-12 from dietary proteins). Thus, adults over 50 years old are advised to consume foods fortified with vitamin B-12 or a supplement containing B-12, both of which are more available sources to this population. Consult with your physician if you are worried that this might be you.

Individuals who follow a vegan or strict vegetarian diet (B-12 is found in food from animals) and anyone with a digestive problem that impairs absorption of nutrients (e.g., celiac disease, Crohn’s) are also at a higher risk of vitamin B-12 deficiency. Consult your physician if you fall into one of these categories.

What happens if you get too much?

It’s not likely that you will experience harmful effects from consuming too much vitamin B-12, because your body can only absorb a small amount of the B-12 you receive from foods and supplements. However, moderation is still the best approach, as studies have not specifically looked at the harmful effects of excess vitamin B-12.

High intakes of beta carotene from foods have not been shown to be toxic in humans, but may cause an unwanted side effect: yellow (or orange) skin. Fortunately, the beta-carotene tinge is harmless and only temporary. High doses of preformed vitamin A from animal foods or supplements can cause both acute (short-term) or chronic toxicity. Signs of short-term vitamin toxicity include nausea, vomiting, headache, dizziness and blurred vision. Chronic toxicity (due to ingestion of large doses for months or years) is often characterized by dry itchy skin, loss of appetite, headache, birth defects, liver abnormalities, central nervous system disorders, and bone and joint pain. Getting too much preformed vitamin A may also result in reduced bone mineral density, which can lead to osteoporosis.

Vitamin B-12-rich recipes on Delish:

From www.eatingwell.com with permission. © 2009 Eating Well Inc.

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