February 22, 2024
Many Vitamin Fads Come and Go, But Vitamin B12 is Not to Be Ignored

Many Vitamin Fads Come and Go, But Vitamin B12 is Not to Be Ignored

Many Vitamin Fads Come and Go, But Vitamin B12 is Not to Be Ignored

Author: Kate Findley
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By Roberta H. Anding, MS, Baylor College of Medicine and Texas Children’s Hospital
Edited by Kate Findley and proofread by Angela Shoemaker, The Great Courses Daily

Over the years, many supplements such as vitamin E have been hyped by the media. Vitamin B12, however, is worth the hype. For a variety of reasons, many of us have this vitamin deficiency. Professor Anding describes the roles of Vitamin B12 and what leads to a deficiency.

Many Vitamin Fads Come and Go, But Vitamin B12 is Not to Be Ignored
Due to the natural aging process, people over age 50 start declining in their absorption of vitamin B12 from food sources and should consult their physicians about needing a supplement. Photo By Tatjana Baibakova / Shutterstock

Vitamin B12 Roles

Vitamin B12 is unique to the B vitamin family. The body can store a supply of vitamin B12 up to two years in the liver, as opposed to all the other B vitamins where you need to have a consistent daily intake.

B12, like folic acid, is needed in the production of red blood cells, as well as the maintenance of a normal central nervous system. It also plays a key role in the metabolism of fat, protein, and carbohydrate.

The absorption of vitamin B12 requires the production of adequate stomach acid, and it also requires intrinsic factor. Intrinsic factor is secreted by the parietal cells in the stomach that unlocks vitamin B12 from food.


Gastric bypass, used for the management of obesity, reduces the amount of acid that the stomach produces because the stomach is now smaller, and by extension it reduces the amount of intrinsic factor that interacts with the food. The loss of the gastric juice or hydrochloric acid also occurs naturally with the aging process. About 30% of those over 50 years old can suffer from malabsorption of the vitamin. 

“When the physician told my mother that she had a problem with her red blood cells, my mother assumed that was iron because that’s what she knew,” Professor Anding said. “What she actually had was a B12 deficiency, not because she doesn’t eat food sources of B12, but the problem is she didn’t have enough intrinsic factor because she’s 85 years old.”

B vitamin deficiencies can take years to develop, so someone who has just experienced gastric bypass can have adequate B12 in their blood on their first visit to the doctor. Over a period of time, they lose that ability to absorb adequate amounts from their diet. 

Sometimes to compensate for a deficiency, you can take injections or a large oral dose of up to 500 milligrams. However, the injections only work if you’re already B12 deficient, not as a prevention strategy.

Other populations at risk include vegans because vitamin B12 is found in animal products. If a vitamin B12 deficiency goes on untreated, you can actually develop a form of anemia called pernicious anemia, an inappropriate immune response. 

You end up with a macrocytic anemia, a large cell anemia, and you can have irreversible nerve destruction. Recent research also suggests that a deficiency of B12, as with folate, may increase the likelihood of neural tube defects, illustrating again the interaction of B vitamins. 

If you’re at risk, you must monitor your B12 status carefully. Vitamin B12 has no known toxicity.

Heart Disease and B Vitamins

A relationship between B vitamins and heart disease exists due to the synergy between B vitamins. B6, folate, and B12 all work closely together, and a deficiency of any one of these vitamins can increase the level of homocysteine in the blood. 

Perhaps you’ve had a homocysteine level drawn by your health care provider. An increased level of the protein homocysteine is a marker for an increased risk of heart disease. The question then becomes, is it homocysteine directly that causes an increased risk of heart disease, or is it a marker for a poor diet?

Professor Anding suggests that it is also a potential marker for these B vitamin interactions. For example, suppose you eat well, but you drink significant amounts of alcohol with your friends on the weekend. Then you must ask yourself, are increased homocysteine levels an indication that your diet is poor, or is it the effect that alcohol has on all of these B vitamins? 

“This is a wonderful example of how nutrition is all woven together, and the B vitamin family really illustrates this probably as well as anything in clinical nutrition,” Professor Anding said. 

This article was edited by Kate Findley, Writer for The Great Courses Daily, and proofread by Angela Shoemaker, Proofreader and Copy Editor for The Great Courses Daily.

Professor Roberta H. Anding is a registered dietitian and Director of Sports Nutrition and a clinical dietitian at Baylor College of Medicine and Texas Children’s Hospital. She also teaches and lectures in the Baylor College of Medicine’s Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, and in the Department of Kinesiology at Rice University.

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