NUTRIENT LIBRARY

Nutrient Library - Vitamin B12

Vitamin B12

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?
What are some recipes that are good sources of vitamin B12?
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What does it do?

Vitamin B12 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 B12 is 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.

Life Stage Group	Recommended Dietary Allowance / Adequate Intake (see note below)	Tolerable Upper Intake Level (UL)
Infants	(micrograms/day)
0-6 mo. 7-12 mo.	0.4* 0.5*	Not determinable due to lack of data on adverse effects and concern about inability to handle excess amounts. Source should be from food only to prevent high levels of intake.
Children
1-3 yr. 4-8 yr.	0.9 1.2
Males
9-13 yr. 14-18 yr. 19-30 yr. 31-50 yr. 51-70 yr. > 70 yr.	1.8 2.4 2.4 2.4 2.4 2.4
Females
9-13 yr. 14-18 yr. 19-30 yr. 31-50 yr. 51-70 yr. > 70 yr.	1.8 2.4 2.4 2.4 2.4 2.4
Pregnancy
< 18 yr. 19-30 yr. 31-50 yr.	2.6 2.6 2.6
Lactation
< 18 yr. 19-30 yr. 31-50 yr.	2.8 2.8 2.8

NOTE: The table is adapted from the Dietary Reference Intakes reports. Recommended Dietary Allowances (RDAs), when available, are in bold type; Adequate Intakes (AIs) are followed by an asterisk(*). RDAs and AIs may both be used as goals for individual intake. RDAs are set to meet the needs of almost all individuals (97 to 98 percent) in a group. For healthy breastfed infants, the AI is the mean intake. The AI for other life stage and gender groups is believed to cover the needs of all individuals in the group, but lack of data means the percentage of individuals covered by this intake cannot be specified with confidence.
UL = The maximum level of daily nutrient intake that is likely to pose no risk of adverse effects. Unless otherwise specified, the UL represents total intake from food, water and supplements.

What are the best food sources?

Vitamin B12 is found naturally in animal-based foods, such as meat, fish, poultry, eggs and dairy foods. Particularly rich sources of vitamin B12 include shellfish, herring, sardines, trout and some game meats. Vegans and strict vegetarians can get B12 from some fortified foods, such as ready-to-eat cereals and meal replacements (e.g., bars and drinks). See more food sources and calculate your daily intake.

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 B12. This may be because of a decrease in the production of stomach acid with age (which is needed to extract B12 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 B12 from dietary proteins). Thus, adults over 50 years old are advised to consume foods fortified with vitamin B12 or a supplement containing B12, 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 (B12 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 B12 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 B12, because your body can only absorb a small amount of the B12 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 B12.