February 2016: To B or Not to B: The Essence of B[12]eing

The eight B vitamins help the body convert food (mostly carbohydrates) into fuel (glucose), which is used to produce energy. Often referred to as B complex vitamins, they help the body use fat and protein; they are needed for healthy skin, hair, eyes, and liver; and they help the nervous system function properly.

B12, also called cobalamin, is known as a super B vitamin because it offers varied benefits, such as maintaining healthy nerve cells and helping in the production of DNA and RNA, the body's genetic material. Vitamin B12 helps iron work better in the body and helps B9, also called folate or folic acid, make red blood. Folate and B12 also work together to produce S-adenosylmethionine (SAMe), a compound involved in enhancing immune function and mood.

Having low levels of vitamin B12 in the body are rare because it stores several years' worth of B12 in the liver. However, decreases in B12 levels are common in the elderly. Also, because 10 to 30% of older people don't absorb B12 from food very well, people over the age of 50 should get their daily B12 requirement by eating foods fortified with B12 or taking a supplement containing B12. Other groups with low levels of B12 are HIV-infected persons, people with eating disorders, people with H. pylori (an organism in the intestine that can cause ulcers and inhibit B12 absorption), and people with nutrient-absorbing conditions like Crohn's disease, pancreatic disease, or the aftereffects of weight-loss surgery.

Low levels of B12 can cause a range of symptoms including fatigue, shortness of breath, diarrhea, nervousness, numbness, or tingling sensation in the fingers and toes. A severe deficiency of B12 can cause nerve damage.

Some evidence suggests that a B12 deficiency is related to age-related macular degeneration, breast cancer, and male infertility. However, the research is not conclusive, and the pathways of how this deficiency plays out in each of these conditions is unclear.

Dietary Sources

Lamb Ragu

Lamb Ragu

Animal foods and fortified foods contain vitamin B12 in abundance. The richest dietary sources include fish, shellfish, dairy products, organ meats (particularly liver and kidney), eggs, beef, duck, lamb, and pork. Some people argue that vegetarians and vegans don't get enough B12. However, one's daily B12 requirement can easily be met through various vegan/vegetarian foods.

Nutritional yeast, such as Red Star Vegetarian Support Formula and brewers yeast, are excellent B12 vegetarian sources. Nutritional yeast can be added to roasted vegetables, soups, and baked dishes. It can even be sprinkled on salads for a more hearty flavor.

Vitamin B12-Fortified soy-based foods

Vitamin B12-Fortified soy-based foods

Fortified foods made from wheat gluten (seitan) or soybeans (tempeh and tofu), fortified breakfast cereals and energy bars (check the ingredient list to make ensure they are not loaded with added sugars and sodium), and fortified soy and almond milk contain many of the essential B vitamins. If taking B12 as a multivitamin, check the nutrition label or the ingredient list to ensure you are receiving the active form of B12: cobalamin or cyanocobalamin.


Because of possible side effects or interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Taking a single B vitamin for a long period of time can result in an imbalance with other important B vitamins. For this reason, you may want to take a B complex vitamin that contains all eight B vitamins. Taking folic acid (B9) at high doses can help lower a vitamin B12 deficiency, so these vitamins are often taken together. Talk to your doctor before taking more than 800 mcg of folic acid.


People with abnormal levels of red blood cells or abnormalities in their red blood cells should work with a physician to determine whether B12 is appropriate for them. In some instances, it can be beneficial, while in other conditions, it can be harmful. Again, work with your physician.

Possible Interactions

If you are currently being treated with any medication that reduce levels of vitamin B12 in the body, you should not use B12 supplements without first talking to your health care provider.

These types of medications include the following:

  • Anti-seizure medications

  • Chemotherapy medications

  • Medications for treating gout, especially Colchicine

  • Bile acid sequestrants used to lower cholesterol

  • H2 blockers and Proton pump inhibitors used to reduce stomach acid

  • Medication taken for diabetes

  • Antibiotics, Tetracycline

Vitamin B12 and other B vitamins should not be taken at the same time as tetracycline because they interfere with the absorption and effectiveness of this medication. In addition, long-term use of antibiotics can lower vitamin B levels in the bodyparticularly B2, B9, and B12and vitamin H (biotin), which is considered part of the B complex vitamins.


  1. Vitamin B 12 Overview. University of Maryland Medical Center.
  2. Vitamin B12, Mayo Clinic.
  3. Vitamin B12 in Vegetarian Diets, Resources for Consumers, Academy of Nutrition and Dietetics.
  4. Vitamin B12: A Simple Solution. Physicians Committee for Responsible Medicine.
  5. Vitamin B12 in a Vegan Diet. The Vegetarian Resource Group.
  6. Vegetarian Vitamin B12 Sources and List of Sources. OldWays: Health through Heritage