4 Medications That Can Affect Vitamin B12 Absorption

Reviewed by Dietitian Katey Davidson, M.Sc.FN, RD, CPT

Key Points

• Certain medications may interfere with vitamin B12 absorption and increase deficiency risk.

• Metformin and acid-suppressing medications may lower vitamin B12 levels with long-term use.

• Talk with your health care provider about B12 testing and supplementation if needed.

Vitamin B12 is a water-soluble vitamin involved in many processes in the body, including red blood cell formation, DNA synthesis and neurological function. It’s found in foods like meat, fish, dairy and fortified foods, and it can also be taken as a supplement.

Although vitamin B12 deficiency affects a relatively small percentage of U.S. adults, insufficient levels can still be a concern. Long-term use of certain medications is one potential contributing factor. Ahead, pharmacists and registered dietitians share four medications that may interfere with vitamin B12 absorption and how to help maintain healthy levels.

1. Colchicine

Colchicine is a medication commonly prescribed to treat gout, a type of inflammatory arthritis that can impact physical functioning and decrease quality of life during flares. Gout is more common in middle-aged men than women, but the risk can also increase in females during menopause. Additionally, people with chronic conditions such as high blood pressure, obesity, diabetes and heart disease are at higher risk of developing gout.

If you take colchicine to manage gout, talk with your health care provider about whether your vitamin B12 levels should be tested.

“Colchicine can interfere with vitamin B12 absorption in the small intestine, particularly with prolonged use. This can contribute to lower B12 levels and potentially deficiency,” shares Sonia Amin Thomas, Pharm.D., BCOP, AFMCP.

2. Metformin

Metformin, a commonly prescribed medication for managing prediabetes and type 2 diabetes, is another medication that pharmacists agree can affect vitamin B12 absorption.

“Long-term metformin use can reduce vitamin B12 absorption and lower B12 levels,” says Anuolu Bank-Oni, Pharm.D., CDE, BCGP.

Luciana Soares, D.C.N., M.S., RDN, LDN, CDP, FAND, agrees, explaining that the medication can affect vitamin B12 absorption. “Long-term metformin use can interfere with B12 absorption in the small intestine, and the risk of B12 deficiency can increase with longer treatment duration,” she says.

Research supports this association, linking metformin use with lower vitamin B12 levels and an increased risk of deficiency. If left unaddressed, B12 deficiency can contribute to neurological complications, including peripheral neuropathy. This may be particularly concerning for people with diabetes, who are already at risk for nerve damage. Some research has also examined the relationship between B12 deficiency and diabetic cardiovascular complications, including cardiac autonomic neuropathy, which can affect heart rate and cardiovascular function.

3. H2-Receptor Antagonists

H2-receptor antagonists, such as famotidine, cimetidine and nizatidine, are medications that reduce stomach acid production. They’re prescribed for conditions such as gastroesophageal reflux disease (GERD), heartburn and peptic ulcer disease.

H2-receptor antagonists have been shown to interfere with vitamin B12 absorption from food. This is because vitamin B12 in food is bound to proteins and requires stomach acid to be released before it can be absorbed. By reducing stomach acid production, these medications can make it harder for the body to absorb B12 from food.

However, Bank-Oni notes that there’s an important distinction when considering vitamin B12 from food and supplemental form. “Acid-suppressing medications mainly affect B12 that is naturally bound to food. B12 in supplements is already in a free form and does not require stomach acid to be released from food before absorption.”

If you take medication for heartburn, GERD or stomach ulcers, speak with your health care provider about whether your vitamin B12 levels should be monitored.

4. Proton Pump Inhibitors

Proton pump inhibitors (PPIs), such as omeprazole, esomeprazole and lansoprazole, are another class of medications that reduce stomach acid production. They’re used to treat conditions such as GERD and peptic ulcer disease.

Like H2-receptor antagonists, PPIs reduce stomach acid, which can make it harder to release vitamin B12 from food proteins. As a result, people taking these medications may be at risk of vitamin B12 deficiency, particularly with long-term use.

“Stomach acid is necessary to release vitamin B12 from the proteins in food so it can be absorbed, which can lead to deficiency,” shares Thomas.

Since supplemental B12 is already in a free form, Bank-Oni encourages patients to work with their health care team to identify the right form of supplementation that may be warranted based on B12 levels.

Safety and Precautions

Consider these precautions from health care experts as you evaluate if vitamin B12 supplementation is right for you.

• Know Your Unique Needs. “Taking one of these medications does not automatically mean you need a vitamin B12 supplement,” Tracee Yablon-Brenner, RD, CLT, HHC. “Consider your age, medical history and how long you have been taking the medication.”

• Consult Your Health Care Provider. “Someone taking any of these medications should not stop their medication or automatically start B12 based solely on an interaction list,” says Bank-Oni. “Their risk factors, medication history and need for B12 testing should be assessed first with their physician.”

• Use the Right Form. “Vitamin B12 supplements are available in oral and sublingual forms, as well as an injectable prescription form,” notes Soares. “The appropriate choice depends on a person’s B12 status, the cause of the deficiency and whether malabsorption is present.”

• Testing and Monitoring Your Levels. Experts agree that testing and monitoring vitamin B12 levels may be appropriate for people taking medications that can affect absorption, particularly with long-term use.

Our Expert Take

Certain medications, like colchicine, metformin and acid-suppressing medications, may lower vitamin B12 levels. If you take one of these medications, talk with your health care provider about whether testing is appropriate and how to meet your vitamin B12 needs through food and, if necessary, supplementation.

Read the original article on EatingWell