A Guide to Vitamin B12 Supplements

Last Updated on March 10, 2010 by Jimson Lee

In January, I wrote 2 articles on Vitamin B12 Deficiency Debate and Why is Vitamin B12 the Scapegoat.

Mitch Pellecchia of VitaCost.com submitted this article, along with several others with topics ranging from Protein Powders, Amino Acids, and Essential Fatty Acids and Fish Oil. I like the fact that he cites all his references at the end of the article. He must have taken lessons from Lyle McDonald!

So What is Vitamin B12 and Cobalamin?

Vitamin B12, also known as cobalamin, is a water-soluble nutrient required in tiny amounts for essential metabolic reactions in the body. It’s crucial to normal brain function and nervous system health and works in concert with folic acid and vitamin B6 to metabolize food and maintain healthy immune function. Vitamin B12 is key in the formation of red blood cells in bone marrow and aids the body in optimizing the use of iron.

The cobalamin group of B12 vitamins includes hydroxocobalamin, methyl-cobalamin and cyanocobalamin, the latter of which is the principal form of B12 used in nutritional supplements and to fortify food. Vitamin B12 has one of the most complex chemical structures of any essential vitamin and the only one known to contain cobalt, the mineral element responsible for the effective transport of glucose to body cells and one said to aid in the repair of the myelin sheath, an insulating layer that surrounds healthy nerve fibers and facilitates the transmission of electrical impulses in the body. Vitamin B12 is needed for DNA replication and to produce mood-affecting substances such as SAMe (S-adenosyl-L-methionine) in the brain.

Vitamin B12 is also said to be essential in controlling homocysteine, high levels of which in the blood have been linked to diminished cardiovascular health, neurological brain injury and vascular disorders.

Recommended Daily Intake (RDI) of vitamin B12

The National Institutes of Health Office of Dietary Supplements suggests the RDI (Recommended Dietary Intake) of vitamin B12 is 0.9 mcg (micrograms) a day for children 1 to 3 years old, and 1.2 to 1.8 mcg for children ages 4 to 13. Roughly 2.4 mcg daily is recommended for adults, and heightened levels of vitamin B12 are suggested for pregnant and lactating women.

B12 benefits; claims

Other than being an essential part of a balanced diet and necessary to good health, high doses of vitamin B12 may be effective in aiding trauma patients and those exposed to infection, burns, fatigue and stress. Research suggests that B12 supplementation may improve respiratory vigor, boost arterial flow, aid intestinal inflammation, stabilize mood disorders, help to balance blood sugar and cholesterol levels and aid bone strength – although there is little clinical evidence to back the efficacy of such claims.

The most recent health benefit associated with vitamin B12 is its effectiveness in lowering homocysteine levels in the blood. Elevated homocysteine can be toxic and has been linked to diminished cardiovascular health and the thinning of the hippocampus, the part of the brain believed to be responsible for memory, learning and personality.

Vitamin B12 is needed to metabolize carbohydrates, fat and protein and is essential in the absorption of calcium. Vitamin B12 is crucial to maintaining a healthy nervous system, promoting growth in children and sustaining healthy energy levels.

Sources of vitamin B12

Vitamin B12 occurs naturally in animal food sources only. These include chicken liver, beef, lamb, tuna, flounder, liverwurst, eggs, and dairy products. Clams and beef liver are extraordinarily high in cobalamin, and although some plant foods contain cobalamin, it’s not a B12 form beneficial to humans. Yeast extracts such as brewer’s yeast contains vitamin B12, and many breakfast cereals and other foods are fortified with vitamin B12 as indicated on labels.

B12 deficiency; symptoms

Vitamin B12 deficiency is characterized by anemia – a decline in the number of red blood cells or the amount of hemoglobin in the blood. Two types of anemia are predominant:

1) Megaloblastic anemia results from inadequate intake of B12 in the diet. This type of anemia is typical of those with extremely poor diets and victims of malnutrition. In patients with bulimia or anorexia nervosa, B12 deficiency can be related to diet.

2) Pernicious anemia results from poor absorption of vitamin B12 into the body system due to lack of intrinsic factor (IF), a normal stomach substance which facilitates vitamin B12 absorption. Pernicious anemia is most common in people with poor immune function and those who suffer from autoimmune disorders. Because the amount of IF produced by the stomach diminishes with age, pernicious anemia is common to the elderly. Vitamin B12 absorption can also be impaired by low levels of folic acid, iron or vitamin E in the blood.
Fatigue is typically the first sign of B12 deficiency, along with dizziness, heart palpitations, weight loss and shortness of breath. The tongue may be sore and have a beefy, red appearance and the skin and eyes may develop a yellowish tinge. Too low levels of B12, if left unattended, may result in diminished muscle strength, numbness and tingling of limbs, memory loss, confusion, delusion, poor balance and reflexes, hearing difficulties, irritability and dementia.

Because the liver stores vitamin B12 for up to five years, it is rare that diet causes vitamin B12 deficiency. However, vegans are most susceptible because of the lack of animal products in their diet and may benefit from B12 supplementation.

Severe clinical deficiencies of B12 have been reported in infants exclusively breastfed by vegan mothers. Vitamin B12 deficiency can also develop in those who have had part or all of their stomach surgically removed.

Long term deficiencies of vitamin B12 may result in high homocysteine levels, which can be a detriment to brain function and severely diminish cardiovascular health.

B12 side effects; cobalamin toxicity

Adverse effects resulting from B12 supplementation are rare. Symptoms of hypersensitivity to cobalamin include swelling, itching and shock. It is advised that those who share the hereditary optic nerve atrophy known as Leber’s disease avoid cobalamin supplementation, as should people sensitive or allergic to cobalt or cobalamin.

Clinical studies and B12 research

At the time of this writing, vitamin B12 was being researched heavily for its potential, along with folate and vitamin B6, in delaying cognitive decline and dementia. People with elevated homocysteine levels are said to be at high risk of developing degenerative brain disease, according to a new report from scientists at Boston University. A later report, published in The New England Journal of Medicine, provides compelling evidence of an association between high plasma homocysteine and significant memory loss later in life.

The journal Epidemiology suggested in 2007 that the mandatory fortification of enriched grain products with folic acid and B12 was long overdue. Experts suggested that if recommendations for B12 fortification were followed, cases of neural tube defects would be reduced significantly and the overall brain and heart health of both children and adults would improve over time.

B12 safety, efficacy and the FDA

Although vitamin B12 has been scientifically proven to be necessary in maintaining a healthy nervous system and for the metabolic utilization of fats, proteins and carbohydrates, the vitamin remains recognized only as a dietary supplement by the FDA and is not regulated by the agency. The FDA has, however, approved a number of pharmaceutical drugs that target vitamin B12 deficiency and anemia and which are currently on the market.

It is of interest that excessive use of nicotine products and alcohol is proven to significantly deplete vitamin B12 stores in the body.

References:

1. Vitamin B12 Source Citation: “Vitamin B12.” Judith Turner. The Gale Encyclopedia of Alternative Medicine. Ed. Jacqueline L. Longe. 2nd ed. Detroit: Gale, 2005. 4 vols. Updated July 1, 2006.
2. Obesity in children/adolescents linked with risk of low vitamin B12. Matthew Boylan. Journal of the Australian Traditional-Medicine Society. March 2007 v13 i1 p26(2).
3. Vitamin B12. CareNotes. May 2007 pNA.
4. Vitamin B12 Deficiency. Health A-to-Z. May 17, 2007 pNA
5. Vitamin B12. Section 2: Key nutrients delivered by red meat in the diet.
   A. Stewart Truswell. Nutrition & Dietetics: The Journal of the Dietitians Association of Australia. Sept 2007 v64 i3 pS120(6).
6. Folic acid fortification should include B12. Nutraceuticals International. June 2007 pNA.

For more information on Vitamin B12, visit www.VitaCost.com/Vitamins/Vitamin-B12.