Eat Well to Be Well: Vitamin B12 – A little goes a long way toward keeping us healthy

They say good things come in small packages and if that’s true, vitamin B12 is a very good thing. Out of the 13 vitamins needed for human health, this one has the smallest Recommended Dietary Allowance (RDA) amount required at only 2.4 micrograms a day for both males and females, ages 14 and up.

Despite the miniscule amount needed, vitamin B12 has the largest and most complex chemical structure. Also, it can be one of the more difficult vitamins to correctly diagnose a deficiency within a person. Delayed diagnosis can lead to various neurological abnormalities along with other harmful symptoms if left unchecked.

History of vitamin B12 – As far back as the 1850s, pernicious (meaning “deadly”) anemia was understood to be caused by the lack of intrinsic factor, a protein made in the stomach lining. When intrinsic factor is lacking, dietary vitamin B12 cannot be absorbed, leading to pernicious anemia. Despite this knowledge, the discovery of vitamin B12 would not take place until nearly a century later and meanwhile the condition remained fatal. It wasn’t until 1926, when researchers George Minot and William Murphy reported that eating large amounts of liver (a rich source of vitamin B12) was effective at treating pernicious anemia. They were awarded the Nobel Prize for Medicine for their discovery. Finally in 1948, vitamin B12 was isolated, giving it the unique distinction of being the last vitamin to be discovered.

Functions of vitamin B12 – Also known by its chemical term cobalamin because it contains the mineral cobalt, vitamin B12 works closely with another water-soluble vitamin folate, as they are dependent on each for activation. On its own, vitamin B12 is necessary to produce ATP, or adenosine triphosphate, from certain fatty acids, to make red blood cells and DNA, and to maintain the myelin coating which protect nerve fibers.

Where can it be found? – An easy way to remember sources of vitamin B12 is that it is found only in foods of animal origin. As long as a person is eating meat, fish, poultry, milk, cheese, or eggs, they should not be at risk of a vitamin B12 deficiency. For strict vegetarians, avoiding the development of a deficiency will require either consuming foods fortified with vitamin B12 such as fortified breakfast cereals and fortified soymilk – or taking a vitamin B12 supplement.

Causes of deficiency – There are numerous ways to become vitamin B12 deficient and several groups of people are prone to deficiency:

  • Older adults: About 10-30 percent of older adults will have atrophic gastritis which decreases the secretion of hydrochloric acid in the stomach which is necessary to release vitamin B12 which is bound to protein in food. Without sufficient hydrochloric acid, vitamin B12 from food sources cannot be absorbed. However the vitamin can be absorbed from foods fortified with synthetic vitamin B12 and dietary supplements as they are in a free form and do not require any separation process.
  • People with pernicious anemia: This autoimmune disease affects gastric mucosa leading to the inability to produce intrinsic factor, resulting in vitamin B12 malabsorption, despite a person’s adequate intake of the vitamin. Pernicious anemia is treated with intramuscular or subcutaneous injections of vitamin B12.
  • People with celiac or Crohn’s disease: Individuals with these conditions may be unable to absorb proper amounts of vitamin B12. In celiac disease, villi that line the walls of the small intestine are damaged, reducing the ability to absorb many nutrients including vitamin B12. Crohn’s disease also causes malabsorption issues with vitamin B12.
  • Those who have had weight loss surgery: Stomach stapling or surgery to remove part of all of the stomach can cause a loss of cells that secrete hydrochloric acid and intrinsic factor. Vitamin B12 from food sources are at risk as the absorption rate is dramatically reduced.
  • Strict vegetarians: People who consume only food from plant sources (vegan) are automatically at risk for a deficiency. Consuming foods fortified with vitamin B12, such as breakfast cereals, can help avoid this risk.

People who frequently use antacids can increase their risk of a deficiency. A 2013 study in the Journal of the American Medical Association demonstrated frequent use of antacids were associated with an increased risk of vitamin B12 deficiency. Antacids are commonly used to reduce stomach acid. Stomach or gastric acid is necessary to release vitamin B12 from dietary sources in order to be absorbed. When this acid is reduced, they can inadvertently cause malabsorption of vitamin B12.

“When you deplete all the acids from the stomach by overuse of antacids, watch out,” said Dr. David Samadi, Chairman of Urology and Chief of Robotic Surgery at Lenox Hill Hospital, in New York City. “We need stomach acid for absorption of vitamin B12 and taking more antacids than necessary can get you into trouble with a deficiency.”

Signs and symptoms of a deficiency – Symptoms of vitamin B12 deficiency can be found in both the circulatory and nervous systems. Since many of the symptoms tend to be vague and can also be related to other various medical conditions, getting a correct diagnosis by a skilled health professional is crucial to treating the deficiency as soon as possible and to avoid permanent damage.

Circulatory symptoms include:

  • Fatigue
  • Weakness
  • Shortness of breath
  • Pale appearance
  • Heart palpitations
  • Megaloblastic anemia – Anemia characterized by large immature red blood cells in the bloodstream that cannot carry oxygen properly; this occurs in folic acid deficiency and pernicious anemia.

Neurological symptoms include:

  • Tingling and numbness in extremities
  • Abnormal gait and difficulty in maintaining balance
  • Depression
  • Dementia, memory loss or disorientation

Folic acid and vitamin B12 – Diagnosing vitamin B12 deficiency becomes a challenge if a person is consuming large amounts of folic acid (more than 1,000 mcg daily) in their diet or using a supplement. If a person is diagnosed with megaloblastic anemia, they will receive extra folic acid, which clears up the condition, but this also will mask a vitamin B12 deficiency that goes undetected. This can lead to permanent neurological damage such as malfunctioning of nerves and muscles. If a person needs to take extra folic acid, periodic testing of vitamin B12 levels is suggested.

Alzheimer’s disease and vitamin B12 – Sometimes people diagnosed with Alzheimer’s disease have been found to have abnormally low vitamin B12 levels.

“Lack of vitamin B12 mimics symptoms of Alzheimer’s,” said Dr. Samadi.

Symptoms of Alzheimer’s are similar to some of the neurological symptoms associated with a vitamin B12 deficiency, leading to speculation. Studies thus far on the effects of vitamin B12 supplementation on the prevention or progression of Alzheimer’s remain unclear. Additional studies are required to validate a connection.

“In the meantime, it is important to have an elderly person exhibiting the symptoms of dementia go to their physician and have their vitamin B12 levels checked to rule out a possible diagnosis of Alzheimer’s,” advises Dr. Samadi.

Treating a vitamin B12 deficiency – Before vitamin B12 deficiency is diagnosed, the levels must be checked with a blood test. Normal results are between 200-900 pg/ml (picograms per milliliter). Homocysteine and methylmalonic acid levels should also be checked as they tend to be elevated when a person is deficient in vitamin B12. Once a person is diagnosed with a deficiency, a physician will determine the route, dosage, treatment timing, and follow-up. Depending upon what specifically is causing the vitamin B12 deficiency, treatment may include either an intramuscular or subcutaneous dose of vitamin B12, oral supplements or an intranasal remedy. Before self-diagnosing or trying self-remedies with vitamin B12 supplementation, always consult with your physician to achieve the best results.

Sources:
Grosvenor, M. & Smolin, L. (2012). Visualizing Nutrition Everyday Choices. New Jersey: John Wiley & Sons.
Lutz, C., Mazur, E. & Litch, N. (2011). Nutrition and Diet Therapy. Philadelphia: F.A. Davis Company.
Sizer, F. & Whitney, E. (2011). Nutrition Concepts & Controversies. Belmont: Wadsworth.
Lam JR, Schneider JL, Zhao W, Corley DA. Proton pump inhibitor and histamine 2 receptor.
Antagonist use and vitamin B12 deficiency. JAMA 2013;310(22):2435-2442.
National Library of Medicine – PubMed Health.
NIH Office of Dietary Supplements.
Harvard Health Publications Harvard Medical School.
Centers for Disease Control and Prevention – Managing Patients with Evidence of a Vitamin B12  Deficiency.


Cheryl_Mussatto_pictureCheryl Mussatto MS, RD, LD, is a registered dietitian who is an adjunct professor at Allen Community College, Burlingame, where she teaches Basic Nutrition, and at Butler County Community College, Council Grove, where she teaches Therapeutic Nutrition. She is also a certified health and wellness coach. She writes Eat Well to Be Well, a column about health and nutrition, and may be contacted at [email protected].

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