Who is at risk for vitamin B12 deficiency?

People at risk for vitamin B12 deficiency are those who either don't consume foods that contain this nutrient or who cannot absorb the nutrient from the foods they eat because of a medical condition, interactions with medications or another reason.

Vitamin B12 is found naturally only in foods that come from animals, including meat, poultry, fish, eggs and dairy products. It is also found in some foods that are fortified with it, including some breakfast cereals, some soymilk and some yeasts. People who consume a vegan or strict vegetarian diet may be at higher risk for vitamin B12 deficiency than people who consume animal products.

Some medical conditions (including Crohn's disease, celiac disease and pernicious anemia) may decrease your body's ability to absorb vitamin B12 from foods and increase your risk for vitamin B12 deficiency. People over age 50 are also at greater risk for vitamin B12 deficiency than younger people because with age the body may make less stomach acid, which is necessary for normal vitamin B12 absorption.

Taking certain medications for long periods of time also raises your risk for vitamin B12 deficiency by interfering with normal absorption of the nutrient. Those medications include some antibiotics, antiseizure medications, cholesterol-lowering drugs, chemotherapy drugs, antacids and peptic ulcer medications, glucophage (Metformin) for diabetes, and others.

Talk to your doctor about whether you might be at risk for vitamin B12 deficiency. A simple blood test can measure your level of vitamin B12. If you are deficient, taking supplements of this nutrient may bring your level back to normal.
Dr. David L. Katz, MD, MPH
Preventive Medicine
Vitamin B12 is found in animal foods (and fortified cereals), so vegans are vulnerable to deficiency. But the most important cause of deficiency has to do with the unique way B12 is absorbed. To get into the bloodstream, B12 must be escorted by a protein called intrinsic factor, produced by cells of the stomach. Many disorders of the stomach, such as gastritis, particularly common after age 50, can interfere with the production of intrinsic factor. This condition is called pernicious anemia. Medications that affect the stomach -- such as aspirin, antacids and proton-pump inhibitors -- can also interfere with intrinsic factor production and result in B12 deficiency. The commonly used diabetes medication, metformin (Glucophage), can do so as well.
Kate Geagan
Nutrition & Dietetics
While you should talk with your doctor about your own personal history, here are some of the broad risk groups for vitamin B12 deficiency:
  • If you’re taking certain medications. An essential step for vitamin B12 absorption occurs in the stomach, where your stomach acid plays a key role in unlocking B12 from your food to make it available to the body. If you’re taking medications that suppress gastric acid production, such as proton pump inhibitors for heartburn, you may be at higher risk for B12 deficiency. Regular consumption of aspirin is also associated with a higher risk of B12 deficiency (approximately one in five adults is taking aspirin every day or every other day), as is the diabetes drug Metformin.
  • If you’ve undergone gastrointestinal surgeries or have gastrointestinal disorders. Gastric bypass or other stomach surgery can compromise the body’s ability for normal, healthy absorption of B12. If you have IBS, Crohn's disease or celiac disease, you are also at a potential higher risk, as you may be unable to absorb enough vitamin B12 from your food or to produce adequate intrinsic factor, a compound needed further along in digestion to absorb B12 in the small intestine.
  • If you’re over age 50. Changes in the stomach lining as we age can reduce the production of gastric acid for up to an estimated 30% of the population; in this case, you no longer can unlock adequate amounts of B12 from the foods you eat. For this reason, it’s recommended that all Americans over age 50 consume 25 to 100 mcg/day of supplemental B12. What’s the difference? In fortified foods and supplements, B12 is already in its free form and doesn’t require gastric acid for separation in the stomach.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.