Symptoms of Vitamin B12 Deficiency

Drugs can interfere with Vitamin B absorption
Some drugs interfere with vitamin B absorption

It’s hard to believe you might have a vitamin deficiency, but if your diet contains mostly processed or fast foods, then it’s possible, if not inevitable. As well, there is a risk when following fad diets or diets that cut out entire food groups that you would lack certain nutrients.

Vitamin B12 (cobalamin) is a water-soluble vitamin that is stored in the body. It may take a while for signs of deficiency to manifest, as it can be stored in the body for as much as five years. Traditional thinking says that vegetarians and vegans are at particular risk of vitamin B12 deficiency, as are the elderly or those who have difficulty with digestion.

However, in their book Fit for Life, Harvey and Marilyn Diamond state that there is less fear of becoming B12 deficient for vegetarians than we have been led to believe. Their reasoning is that “our actual need for vitamin B12 is so minute that it is measured in micrograms…One milligram of vitamin B12 will last you over two years” (102).

They further state that people who eat meat are more likely to have a deficiency, due to improper food combining, which would interfere with intrinsic factor secretion (a protein required to absorb B12) and therefore B12 production.

The Importance of Absorption

It’s not enough to take in a nutrient. You must be able to process, digest, absorb, and use it.

Some drugs can interfere with vitamin B12 absorption or render it metabolically inactive. Some people who lack the intrinsic factor protein cannot absorb B12 in the intestine. They must then either receive B12 injections or take it under the tongue in order to receive its benefits (Balch, 21).

Analogs are compounds that resemble B12 and when they are in food, they attach to B12’s receptor sites, taking its position, but not doing its job. This too can result in B12 malabsorption (Virtue & Prelitz, 88).

The Role Vitamin B12 Plays in the Body

Vitamin B12 helps the body in a number of ways. John Gray, Ph.D., says in his book The Mars & Venus Diet & Exercise Solution that vitamin B12 converts amino acids into dopamine and serotonin (278), and in this way helps one to avoid feeling depressed.

Vitamin B12 also prevents heart disease, protects nerve cells, helps with protein synthesis and metabolizes carbohydrates and fats. It also helps regulate red blood cell formation (Balch, 21).

Signs of Vitamin B12 Deficiency

Some signs of vitamin B12 deficiency are (Balch, 21):

  • bone loss
  • chronic fatigue
  • constipation
  • depression
  • digestive disorders
  • dizziness
  • drowsiness
  • enlarged liver
  • hallucinations
  • headaches/migraines
  • irritability
  • memory loss
  • moodiness
  • nervousness
  • tinnitus
  • pernicious anemia

Foods Containing Vitamin B12

Animal products are the main sources of vitamin B12, which is why vegetarians and vegans are considered to be susceptible to B12 deficiency and should take a B12 supplement. Good sources of B12 include meats, fortified brewer’s yeast, eggs, clams, liver, dairy products, sea vegetables, and soy (Balch, 21).

Spirulina, a blue-green algae, is also a good source of B12 and is recommended as a nutrient-dense superfood in the book Miracle Super Foods that Heal, by Tony O’Donnell, C.N.C., Naturopath. O’Donnell says that scientists have described spirulina as “Nature’s most complete food and a boon for vegetarians” (107).

There is controversy over which form of cobalamin to take when taking B12 as a supplement. Some suggest that cyanocobalamin is a cheap and poor version and that methylcobalamin should be taken. The evidence to support cyanocobalamin as safe and efficacious does exist, however, and many supplements use this form of B12.

It is important to get enough quantities of vitamin B12 from foods that contain them or from quality supplements and to make sure that what is ingested is absorbed and utilized. You should always consult a medical doctor before making any changes to diet or medication.


Balch, Phyllis A., CNC. Prescription for Nutritional Healing: A Practical A-to-Z Reference to Drug-free Remedies Using Vitamins, Minerals, Herbs & Food Supplements, Fourth Edition, New York: Avery, 2006.

Diamond, Harvey and Marilyn. Fit for Life, New York: Warner Books, 1985.

Gray, John, PhD. The Mars & Venus Diet & Exercise Solution, New York: St. Martin’s Press, 2003.

Hathcock, John N., PhD Vitamin and Mineral Safety, Second Edition, Council for Responsible Nutrition (accessed June 5, 2010)

O’Donnell, Tony C.N.C., Naturopath. Miracle Super Foods that Heal, California: Tony O’Donnell, 2001.

Virtue, Doreen PhD, and Prelitz, Becky M.F.T., R.D. Eating in the Light, California: Hay House Inc., 2001.

Image: Sam Catchesides

Disclaimer: The information on this website is not intended to substitute advice from your physician or health-care professional. Before beginning any health or diet program, consult your physician.