Scientists at the Kaiser Permanente Division of Research reviewed the electronic health records of more than 200,000 patients and found that 12% of adults with low levels of B12 also took proton pump inhibitor (PPI) medications for at least two years. Women taking PPIs were more likely to develop B12 deficiencies than men, and higher doses of the medication were more strongly associated with B12 deficiency than lower doses. PPIs work by suppressing the production of acid in the stomach, but it’s gastric acid that’s responsible for helping vitamin B12 get absorbed into the bloodstream. And though we only need small amounts of B12 (the RDA is 2.4 micrograms daily, roughly the amount in a cup of fortified cereal) getting too-low amounts can be serious: If left untreated, B12 deficiency can lead to irreversible dementia, neurologic damage, and anemia. Still, experts say there isn’t yet enough evidence to recommend patients stop taking PPIs altogether. For now, balance is best: If you suffer from chronic acid reflux, GERD, or ulcers, talk with your doctor about taking the lowest level of PPIs possible and getting your B12 levels tested (if they’re low, you can bump them up with a supplement). If your heartburn is mild or occasional, consider opting for a temporary antacid (like Tums, Rolaids, or Maalox) over a PPI, and try incorporating lifestyle changes such as eating smaller meals, drinking less alcohol, or losing weight. (Not sure if your heartburn’s serious? Here’s how to tell.)