Higher than normal levels of Vitamin B12 may indicate cancer risk
Vitamin B12 (cobalamin [Cbl]) is essential for maintaining healthy bodily function but higher than normal levels (reference range 200-600 pmol/L) may indicate that a patient is at risk of developing certain cancers, according to a study published November 18 in the Journal of the National Cancer Institute. Previous studies had suggested an association between high Cbl levels and specific cancers.
To assess the association between high Cbl levels and risk of cancer of any type, Johan Arendt, BSc, of the Department of Clinical Epidemiology and the Department of Clinical Biochemistry of Aarhus University Hospital in Denmark, and colleagues used Danish Medical registries to review the records of 333,667 patients without cancer who had been referred for Cbl testing and to estimate the incidence of cancer in this population from 1998 to 2010.
The researchers excluded patients who had a cancer diagnosis before the date of plasma measurement and those who were receiving Cbl therapy. They found that the risk of cancer overall increased with higher Cbl levels, especially during the first year after measurement and for those with levels > 800pmol/L. They also found that after five years of follow-up, the risk for hematological and alcohol and smoking-related cancers remained high for those with levels > 800pmol/L.
The authors conclude that “…high plasma Cbl levels increased the risk of subsequently diagnosed cancer, mostly within the first year of follow-up.” However, Arendt et al. note that high plasma Cbl levels are probably not related to normal Vitamin B12 intake because consumption of Cbl containing foods or supplements do not increase plasma Cbl levels substantially. Rather, high Cbl levels may result from some unknown malignant process.
What is vitamin B12 deficiency anemia?
Having vitamin B12 deficiency means that your body does not have enough of this vitamin. You need B12 to make red blood cells camera, which carry oxygen through your body. Not having enough B12 can lead to anemia, which means your body does not have enough red blood cells to do the job. This can make you feel weak and tired.
What causes vitamin B12 deficiency anemia?
Most people get more than enough B12 from eating meat, eggs, milk, and cheese. Normally, the vitamin is absorbed by your digestive system-your stomach and intestines. Vitamin B12 deficiency anemia usually happens when the digestive system is not able to absorb the vitamin. This can happen if:
You have pernicious anemia. In this anemia, your body destroys the cells in your stomach that help you absorb vitamin B12.
You have had surgery to remove part of the stomach or the last part of your small intestine, called the ileum camera. This includes some types of surgery used to help very overweight people lose weight.
You have problems with the way your body digests food, such as sprue (also called celiac disease), Crohn’s disease, bacteria growth in the small intestine, or a parasite.
This anemia can also happen if you don’t eat enough foods with B12, but this is rare. People who eat a vegan diet and older adults who don’t eat a variety of foods may need to take a daily vitamin pill to get enough B12.
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Vitamin B12 Deficiency
Vitamin B12 (cobalamin) deficiency is a common cause of macrocytic anemia and has been implicated in a spectrum of neuropsychiatric disorders. The role of B12 deficiency in hyperhomocysteinemia and the promotion of atherosclerosis is only now being explored. Diagnosis of vitamin B12 deficiency is typically based on measurement of serum vitamin B12 levels; however, about 50 percent of patients with subclinical disease have normal B12 levels. A more sensitive method of screening for vitamin B12 deficiency is measurement of serum methylmalonic acid and homocysteine levels, which are increased early in vitamin B12 deficiency. Use of the Schilling test for detection of pernicious anemia has been supplanted for the most part by serologic testing for parietal cell and intrinsic factor antibodies. Contrary to prevailing medical practice, studies show that supplementation with oral vitamin B12 is a safe and effective treatment for the B12 deficiency state. Even when intrinsic factor is not present to aid in the absorption of vitamin B12 (pernicious anemia) or in other diseases that affect the usual absorption sites in the terminal ileum, oral therapy remains effective.
Vitamin B12 (cobalamin) plays an important role in DNA synthesis and neurologic function. Deficiency can lead to a wide spectrum of hematologic and neuropsychiatric disorders that can often be reversed by early diagnosis and prompt treatment.
The true prevalence of vitamin B12 deficiency in the general population is unknown. The incidence, however, appears to increase with age. In one study, 15 percent of adults older than 65 years had laboratory evidence of vitamin B12 deficiency. The nearly ubiquitous use of gastric acid–blocking agents, which can lead to decreased vitamin B12 levels, may have an underappreciated role in the development of vitamin B12 deficiency. Taking the widespread use of these agents and the aging of the U.S. population into consideration, the actual prevalence of vitamin B12 deficiency may be even higher than statistics indicate. Despite these facts, the need for universal screening in older adults remains a matter of controversy.
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ROBERT C. OH, CPT, MC, USA, U.S., Army Health Clinic, Darmstadt, Germany
DAVID L. BROWN, MAJ, MC, USA, Madigan Army Medical Center, Fort Lewis, Washington
Am Fam Physician. 2003 Mar 1;67(5):979-986.
Zachary Rathner
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919-677-2697
Journal of the National Cancer Institute