Researchers from Kaiser Permanente in Oakland, Calif. have published a new study in JAMA that points to the possibility that there may be a link between certain acid-inhibiting medications and vitamin B12 deficiency.

“Vitamin B12 deficiency is relatively common, especially among older adults,” the report states. “[I]t has potentially serious medical complications if undiagnosed. Left untreated, vitamin B12 deficiency can lead to dementia, neurologic damage, anemia, and other complications, which may be irreversible.”

The researchers note that proton pump inhibitors (PPIs) as well as histamine 2 receptor antagonists (H2RAs), both of which are acid-inhibiting medications, inhibit gastric acid production, which the scientists believe may cause a problem with the absorption of vitamin B12 in the stomach. The authors do note, however, that the research is preliminary; further down the road, larger studies would need to be completed before making a clear connection between these drugs and B12 deficiency. “We cannot completely exclude residual confounding [factors besides the drugs] as an explanation for these findings, but, at minimum, the use of these medications identifies a population at higher risk of B12 deficiency, independent of additional risk factors,” the authors wrote in their conclusion.

In the study, the researchers analyzed 25,956 patients in California, and identified which ones had a vitamin B12 deficiency and which ones didn’t. They compared each person’s connection or usage of acid-inhibiting medications. They concluded that a patient on long-term acid-inhibiting medication — 2 or more years of meds — had a larger risk for deficiency. Among those who had vitamin B12 deficiencies, 83.8 percent had not taken PPIs or H2RAs, while in people who did not have a deficiency, 89.6 percent had not had any exposure to the drugs.

PPIs are used to treat several conditions, such as indigestion, peptic ulcer disease, as well as acid reflux. PPIs do, however, cause an increased risk of developing food allergies, as they suppress the breakdown of proteins that are normally controlled by acid. The Harvard Medical School Family Health Guide notes on its website that stomach acid is actually an important feature of our system: “Pepsin, an enzyme that is essential to the preliminary digestion of protein, needs an acidic environment in the stomach to be effective. The strongly acidic hydrochloric acid pumped out by cells in the lining of the stomach also plays a direct role in the early digestion of some foods,” the site continues. “And stomach acidity is a built-in barrier to infection.” Long-term use of PPIs have previously been linked to pneumonia, Clostridium difficile — a species of bacteria that causes diarrhea — as well as a decrease in calcium, according to Harvard Medical School.

Vitamin B12, meanwhile, is an essential vitamin that can be found in meat, shellfish, eggs, milk or nutritional yeasts. Decreased levels of B12 can lead to a loss of balance, numbness or tingling in the arms or legs, weakness or anemia. People who tend to have low levels of B12 are those who are vegan or vegetarian, people over the age of 50, and people with digestive disorders.

However, the researchers of the JAMA study cannot come to a clear stance yet on the issue, and they don’t necessarily advise people to stop acid-inhibiting medications. “These findings do not recommend against acid suppression for persons with clear indications for treatment, but clinicians should exercise appropriate vigilance when prescribing these medications and use the lowest possible effective dose,” the authors wrote. “These findings should inform discussions contrasting the known benefits with the possible risks of using these medications.”

Source: Lam JR, Schneider JL, Zhao W, Corley DA. Proton Pump Inhibitor and Histamine 2 Receptor Antagonist Use and Vitamin B12 Deficiency. JAMA. 2013.310(22):2435-2442.