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Vitamin B12

Eggs

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.

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).

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.

How much do you need?

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

Life Stage Group Age Range Recommended Dietary Allowance/Adequate Intake Tolerable Upper Intake Level (UL)
Infants 0-6 mo. 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.
Infants 7-12 mo. 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. 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 4-8 yr. 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.
Males 9-13 yr. 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.
Males 14-18 yr. 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.
Males 19-30 yr. 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.
Males 31-50 yr. 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.
Males 51-70 yr. 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.
Males > 70 yr. 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.
Females 9-13 yr. 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.
Females 14-18 yr. 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.
Females 19-30 yr. 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.
Females 31-50 yr. 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.
Females 51-70 yr. 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.
Females > 70 yr. 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.
Pregnancy < 18 yr. 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.
Pregnancy 19-30 yr. 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.
Pregnancy 31-50 yr. 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.
Lactation < 18 yr. 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.
Lactation 19-30 yr. 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.
Lactation 31-50 yr. 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.
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