Vitamin B12 Sources and Functions

Vitamin B12 Sources and Functions

All of the B vitamins work together to keep you healthy and feeling good. Here is a summary of the role of vitamin B12 (also known as cobalamin), a water-soluble vitamin, in your good health.

What it does Functions as part of a coenzyme important in new cell formation; Helps release energy from fats and protein; Helps make hemoglobin; Works with folate
Daily needs (mg) [Infants*: .4-.5 µg] [Children†: .9-2.4 µg] [Men: 2.4 µg]
[Women: 2.4 µg] [Pregnant: 2.6 µg] [Lactating: 2.8 µg]
Not enough Pernicious anemia;Folate deficiency
Too Much No known toxic effects
Foods Animal foods: Eggs, Meat, Milk products, Fortified cereals

*The lower value is for infants up to 6 mos., the higher value is for infants up to a year old.
† The first value is for children 1-3 with the amount increasing until age 18.

Note that the recommendation for daily intake of Vitamin B12 is given in micrograms (µg).A microgram is .0001 milligrams (mg), so it is a very small amount.

Destroyed by Microwave

Vitamin B12 is destroyed by microwave heating, so you may want to cook animal foods and fortified cereals using other methods.

Vitamin B12 is special among B vitamins because it contains cobalt, which is a metallic element. The presence of this ion is the basis for all the specialized functions of Vitamin B12. It is also unique among vitamins because it is found almost exclusively in animal foods.


A deficiency of Vitamin B12 is uncommon because the body is able to continuously reuse this B vitamin. However, if the stomach does not contain the proper amount of hydrochloric acid, there may be poor absorption of Vitamin B12. This is particularly prevalent among the elderly, who may have developed gastritis, a chronic inflammation of the lining of the stomach.

Severe vitamin B12 deficiency, caused by an autoimmune response, which destroys the cells of the lining of the stomach, is called "pernicious anemia." This disorder may be an inherited gene defect and is treatable with injections or special nasal sprays.

Caveats for Vitamin B12 Sources and Functions:  

Those following a strict vegan diet should be aware of the potential for Vitamin B12 deficiency, since most good sources of this important B vitamin are from animals.

As with folate, long-term use of antacids may result in Vitamin B12 deficiency.

Alcoholics are also at particular risk for Vitamin B12 deficiency.

Good for pregnancy

Due to its close connection to folate, and its role in preventing birth defects, it is recommended that pregnant women and women who are planning to get pregnant make sure they get enough Vitamin B12. These defects can occur early in the pregnancy, so it is important to maintain proper nutrition even before you decide to have a baby.

Good for the heart

In addition, there is some good research that suggests that Vitamin B12 is a factor in reducing the risk of heart disease, since it is a player in reducing homocysteine levels in the blood, which are correlated with an increase in blood clots and deterioration of arteries.

Fun Fact about Vitamin B12 Sources and Functions: One of the few plant sources of Vitamin B12 is the red skins of peanuts!

Not all the same

Not all sources of Vitamin B12 are created equal. There are some plant-based foods on the market whose labels suggest that they are a good source of Vitamin B12. However, the form the vitamin takes may not be a form that is available to your body. If you take an oral supplement of this vitamin, you should know that of the amount listed on the label, only a portion will actually be absorbed by your body.

Some researchers suggest that the sub-lingual (under the tongue) versions of Vitamin B12 are the best way to take this vitamin as a supplement.

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