Vitamin B12: Avoiding deficiency

If you are chronically fatigued and find it hard to concentrate or think clearly, talk to your doctor. One reason for fatigue may be a Vitamin B12 deficiency.

Vitamin B12 plays a key role in your body’s metabolism. It converts food into energy and keeps your nervous system intact. It helps manufacture healthy red blood cells and produces the genetic DNA material that renews cells.

Causes of Vitamin B12 deficiency

The acid in your stomach helps release Vitamin B12 from your food. As you age, your stomach lining produces less acid. Therefore, if you are over 50, your level of Vitamin B12 is likely less than what it used to be.

Vitamin B12 is naturally found in meat, fish, seafood, eggs or dairy products. If you are eating a highly processed diet or you are a strict vegetarian or vegan, you may be at risk of B12 deficiency.

A B12 deficiency may also be related to how your body absorbs the Vitamin. B12 needs to attach itself to a protein in order to get into your bloodstream. This protein is called the Intrinsic Factor (IF) and is made by your stomach cells.

In some people, the IF is poorly produced. This can be due to a stomach disorder, such as atrophic gastritis or a long-term use of stomach medication, such as antacids or proton-pump inhibitors for peptic ulcers. A daily intake of aspirin or the diabetic medication metformin (glucophage) can also interfere with the IF.

An inadequate production of the IF in your stomach can cause pernicious anemiaa serious condition that needs to be treated by a physician. Other causes of Vitamin B12 deficiency are:

  • Gastrointestinal surgery, including weight loss surgery
  • Helicobacter pylori bacteria in the upper gastrointestinal tract
  • Digestive disorders such as Crohn’s or celiac disease
  • Pancreatic disease
  • People with HIV
  • Immune system disorders such as Graves’ disease or lupus
  • Heavy drinking
  • People with an eating disorder

 Symptoms of Vitamin B12 deficiency

  • Low energy
  • Difficulty concentrating or remembering things
  • Heart palpitations and shortness of breath
  • Weakness and loss of balance
  • Swollen, red and sore tongue
  • Anemia
  • Diarrhea
  • Nausea
  • Mood changes
  • Numbness and tingling in hands and feet
  • Dementia-like symptoms
  • Depression

Treatment for Vitamin B12 deficiency

Your liver can store Vitamin B12 for up to five years. So, if your diet isn’t the healthiest now, you may still have enough B12. However, some people may not know that they have a deficiency. For example, folic acid (vitamin B9), when taken in high doses (more than 800 mcg) can mask the symptoms of a B12 deficiency. Even if you don’t feel any symptoms, you can still be deficient. When left untreated, B12 deficiency can cause nerve and cell damage. If you plan to take a high dose of folic acid, verify your B12 level with your doctor.

Early detection is key to treating B12 deficiency. The longer you wait for treatment, the more difficult it is to reverse symptoms. Also, given the array of symptoms, B12 deficiency can be overlooked or mistaken for another ailment. Being aware of your symptoms and risk factors and communicating with your doctor are important. A physical exam and a blood test can confirm the condition.

As Dr. David Katz points out, if your stomach is working well and it’s just a matter of not getting enough B12 in your diet, taking oral or sublingual B12 supplements, as much as 1000 mcg a day, is effective. If your stomach isn’t working well and you can’t absorb B12, Cyanocobalamin injections can correct the deficiency. For people who can’t metabolize the inactive form of Cyanocobalamin into the active form (due to an enzyme deficiency), then Methylcobalamine taken orally or by injection is the better choice.

 Preventing Vitamin B12 deficiency

Foods naturally rich in Vitamin B12 include milk or yogurt, buffalo or bison, poultry, eggs, beef, pork, clams, sardines, salmon or trout.

The National Institutes of Health recommend the following daily dietary intake of Vitamin B12 in micrograms (mcg):

Table 1: Recommended Dietary Allowances (RDAs) for Vitamin B12 
Age Male Female Pregnancy Lactation
0–6 months* 0.4 mcg 0.4 mcg
7–12 months* 0.5 mcg 0.5 mcg
1–3 years 0.9 mcg 0.9 mcg
4–8 years 1.2 mcg 1.2 mcg
9–13 years 1.8 mcg 1.8 mcg
14+ years 2.4 mcg 2.4 mcg 2.6 mcg 2.8 mcg

* Adequate Intake

People over 50 may need extra B12 from fortified foods or a supplement. Strict vegetarians or vegans, need to get their B12 from fortified breads, grains, cereals or nutritional yeast. People who eat very little or no animal products may need to take B12 supplements.

B12 supplements are normally safe and non-toxic. However, some medications, such as anti-seizure medication, chemotherapy, medication to treat gout, antibiotics (tetracycline), metformin (glucophage) or stomach acid reducers, can interact with B12 supplements and cause side effects. If you have a medical condition, verify with your doctor before taking B12 supplements.

Any mild B12 deficiency can be corrected with a multivitamin, a B complex vitamin or individual supplements. For some people, Vitamin B12 is better absorbed when taken with other B Vitamins (with niacin, riboflavin, Vitamin B6, and magenisum).

A basic multivitamin or B complex vitamin delivers 7.5 mcg of B12, which is more than the average daily need. B12 is available in oral or sublingual tablets, capsules, lozenges, nasal gels or patches and in various dosages. Vitamin B12 comes in 3 forms:

Find out which type of supplement works best for you. Some people prefer hydroxocobalamine or methylcobalamin over cyanocobalamin because they are bioactive and easily absorped.

Hydroxocobalamin is more frequently used in Europe. The literature suggests that hydroxocobalamin is superior to cyanocobalamin and that methylcobalamin may be superior to both types, particularly for neurological disease. Dr. Fred Bloem, MD uses all three forms in his practice and explains the differences among them.

Photo courtesy of: Ragesoss


University of Maryland Medical System. Vitamin B12 (cobalamin).

National Institutes of Health. Vitamin B12.

National Library of Medicine. National Institutes of Health.

Harvard Health Publications. Harvard Medical School. Vitamin B12 deficiency can be sneaky, harmful.

David. L. Katz, MD. Vitamin B12: The Most Important Nutrient You Aren’t Thinking About.

Julie Zimmer

Julie has extensive experience in nursing practice and education in a wide range of fields from intensive/coronary care, to medical-surgical to community and public health. Julie has Bachelor Degrees in Psychology and Nursing, and a Master’s Degree in Community Health Nursing Education. She has taught in faculties of nursing and in various communities in Toronto, Canada and in Geneva, Switzerland, and is a consultant to the International Council of Nurses (ICN). Julie also has years of experience teaching English as a foreign language (EFL) in addition to coordinating an English department in a Swiss private school.

7 thoughts on “Vitamin B12: Avoiding deficiency

  1. I recently heard about a new oral prescription alternative to the injections called Eligen B12. I recently read that it works even if you don’t have intrinsic factor (so even if you don’t have normal gut absorption). Apparently it came out a month or two ago. Have you heard of it?

    1. These tablets contain Cyanocobalamin and are indicated for individuals in which their B12 deficiency cannot be managed by diet alone. However, with any absorption problem, it is better to rule this out first with a physician before opting for an over-the-counter solution.

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