Vitamin B12
Vitamin B12, or cobalamin, is naturally found in animal foods. It can also be added to foods or supplements. Vitamin B12 is needed to form red blood cells and DNA. It is also a key player in the function and development of brain and nerve cells.
Vitamin B12 binds to the protein in the foods we eat. In the stomach, hydrochloric acid and enzymes unbind vitamin B12 into its free form. From there, vitamin B12 combines with a protein called intrinsic factor so that it can be absorbed further down in the small intestine.
Supplements and fortified foods contain B12 in its free form, so they may be more easily absorbed. There is a variety of vitamin B12 supplements available. Although there are claims that certain forms—like sublingual tablets or liquids placed under the tongue to be absorbed through the tissues of the mouth—have better absorption than traditional tablets, studies have not shown an important difference. Vitamin B12 tablets are available in high dosages far above the recommended dietary allowance, but these high amounts are not necessarily the amount that will be absorbed because an adequate amount of intrinsic factor is also needed. In cases of severe vitamin B12 deficiency due to inadequate intrinsic factor (pernicious anemia), doctors may prescribe B12 injections in the muscle.
10ml
Vitamin B12 10ml Vial
This Vitamin B-12 shot can be used at home as an injection, under instruction of a doctor.
Available in 10ml multi-dose vial.
30ml
Vitamin B12 30ml Vial
This Vitamin B-12 shot can be used at home as an injection, under instruction of a doctor.
Avialable in 30ml multi-dose vial.
Recommended Amounts
RDA: The Recommended Dietary Allowance for men and women ages 14 years and older is 2.4 micrograms (mcg) daily. For pregnancy and lactation, the amount increases to 2.6 mcg and 2.8 mcg daily, respectively.
UL: A Tolerable Upper Intake Level (UL) is the maximum daily dose unlikely to cause adverse side effects in the general population. No upper limit has been set for vitamin B12, as there is no established toxic level. However, some evidence suggests that supplements of 25 mcg per day or higher may increase the risk of bone fractures.
Food Sources
Vitamin B12 is naturally found in animal foods such as fish, meat, poultry, eggs, milk, and milk products. Vitamin B12 is generally not present in plant foods. Fortified breakfast cereals are a readily available source of vitamin B12. The vitamin is more available to the body from these cereals for vegetarians. Some nutritional yeast products also contain vitamin B12.
You can get the recommended amounts of vitamin B12 by eating a variety of foods including:
- Organ meats (beef liver)
- Shellfish (clams)
- Meat, poultry, eggs, milk and other dairy foods
- Some fortified breakfast cereals and nutritional yeasts
To find out if vitamin B12 has been added to a food product, check the nutrition fact panel on the food label.
The body absorbs vitamin B12 from animal sources much better than plant sources. Non-animal sources of vitamin B12 have different amounts of B12. They are not thought to be good sources of the vitamin.
Side Effects
Vitamin B12 deficiency occurs when the body does not get or is not able to absorb the amount of the vitamin that the body needs.
Deficiency is most common in people who:
- Are over the age of 50
- Follow vegetarian or vegan diet
- Have had stomach or intestinal surgery, such as weight loss surgery
- Have digestive system conditions such as celiac disease or Crohn disease
Talk to your health care provider about taking vitamin B12 supplements.
Low levels of B12 can cause:
- Anemia
- Dementia
- Loss of balance
- Numbness or tingling in the arms and legs
- Weakness
Recommendations
Recommendations for vitamin B12, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:
Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.
Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.
Dietary reference intakes for vitamin B12:
Infants (AI)
- 0 to 6 months: 0.4 micrograms per day (mcg/day)
- 7 to 12 months: 0.5 mcg/day
Children (RDA)
- 1 to 3 years: 0.9 mcg/day
- 4 to 8 years: 1.2 mcg/day
- 9 to 13 years: 1.8 mcg/day
Adolescents and Adults (RDA)
- Males and females age 14 and older: 2.4 mcg/day
- Pregnant teens and women: 2.6 mcg/day
- Breastfeeding teens and women: 2.8 mcg/day
The best way to meet your body’s vitamin B12 needs is to eat a wide variety of animal products.