Vitamin B12 Facts: Everything You Need to Know

By:    Published: July 21, 2011

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Vitamin B12 is actually only one of eight vitamins that are included in the B vitamins group. Commonly referred to as cobalamin, vitamin B12 is essential for proper body function and development. Meanwhile, it also shares important metabolic functions with the rest of the B vitamins. In this article, we'll explore the functions and uses for vitamin B12 while also covering its various food sources and dosage recommendations.

What Does Vitamin B12 Do?

As mentioned before, all B vitamins play a vital role in helping the body metabolize food. When we eat carbohydrates, fats and proteins, B vitamins help turn those substances into usable energy. This also prevents us from gaining excess weight by using those substances as energy rather than storing them as fat. The B vitamins also contribute to healthier skin and hair and better-functioning eyes and liver.

In addition to sharing duties with the other B vitamins, vitamin B12 has some of its own unique functions. For example, cobalamin helps maintain healthy nerve cells and ensures that the nervous system is working properly. Furthermore, cobalamin encourages the production of genetic materials like DNA and RNA.

In some cases, cobalamin works with other B vitamins to perform specific functions. For instance, vitamins B12, B9 and B6 all contribute to controlling blood levels in homocysteine, an amino acid. This helps to prevent heart disease in some. Additionally, vitamins B9 and B12 work together to regulate S-adenosylmethionine (SAMe) production and the formulation of red blood cells. This can improve the functioning of the immune system.

Because cobalamin is also important for regulating the use of iron in the body, it is sometimes used to treat conditions like pernicious anemia. In some cases, vitamin B12 has also been linked to the prevention of age-related macular degeneration.

Food Sources of Vitamin B12

Unlike many other B vitamins, cobalamin is found naturally only in foods that are from animal sources. Some of the best sources of vitamin B12 are fish, shell fish, liver, kidney, beef and pork. Dairy products and eggs have also been noted as good sources of cobalamin. Because vitamin B12 is found only in animal products, it's important for vegans and vegetarians to consider taking a cobalamin supplement in order to reach their recommended daily dosage of this vitamin. For meat eaters, however, consuming a normal diet is typically sufficient for getting the recommended daily dosage of vitamin B12.

Side Effects

Vitamin B12 is safe and non-toxic, so side effects are extremely rare. However, those who take cobalamin supplements should be aware of the potential interactions with certain medications. For instance, vitamin B12 can reduce the effectiveness of the antibiotic tetracycline. Furthermore, certain medications like anticonvulsants, H2 blockers, proton pump inhibitors, bile acid sequestrants, metformin, colchicines and some chemotherapy medications may reduce the levels of B12 in the body. It's important to always consult a physician before altering your vitamin B12 intake due to potential medication interactions.

Deficiency Symptoms

In general, vitamin B12 deficiencies are not very common. If a person is experiencing a cobalamin deficiency, then they will exhibit a range of symptoms, including diarrhea, fatigue, shortness of breath, numbness, nervousness or tingling in their extremities. A severe vitamin B12 deficiency can be very dangerous. Over time, this deficiency may lead to neurological damage.

There are certain individuals who may be more likely to develop a cobalamin deficiency. Elderly people are more prone to a cobalamin deficiency due to either poor diet or less stomach acid being present in their body. Likewise, vegans and some vegetarians may develop this condition because they don't eat animal-based foods, the source of all naturally occurring B12. Those with HIV and those with eating disorders are also more likely to develop a vitamin B12 deficiency.

Daily Dosage Recommendations

As people grow older, their recommended daily dosage of cobalamin increases. From birth to 6 months of age, babies should have 0.4 micrograms (mcg) of vitamin B12 a day. From 7 to 12 months of age, the recommendation is 0.5 mcg per day. From the ages of 1 to 3 years, children should take 0.9 mcg of cobalamin a day; from ages 4 to 8 years, 1.2 mcg per day; from ages 9 to 13 years, 1.8 mcg; and from age 14 on, 2.4 mcg is the recommendation.

Along with certain health conditions, there is an exception to these standard guidelines for women who are pregnant or breastfeeding. Because vitamin B12 is important for development, pregnant women should take 2.6 mcg of cobalamin a day, while those who are breastfeeding should be sure to get 2.8 mcg each day. Elderly people may also be advised by a physician to take more cobalamin since they may not absorb cobalamin as efficiently as a younger individual. Always consult a physician if you have any concerns about your daily vitamin B12 intake.

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