12/16/2013 10:51 am ET Updated Feb 15, 2014

As the Stomach Churns: The Side Effects of Acid Suppression

As the general public sinks further into scientific illiteracy (70 percent of Americans believe that the double helix is an ice skating maneuver), the nuances and intricacies of the human body get lost. A "something-for-nothing" view of science develops, wherein we suppose we can tinker with the human body with impunity, and new drugs and new interventions do what they're supposed to do and nothing else.

Only it isn't true. A study in the Journal of the American Medical Association this week looked at about 26,000 patients in Northern California who have been diagnosed with vitamin B12 deficiency. The researchers wanted to know if being on acid-blocking medications was associated with low B12 levels, and the answer was "yes." Patients taking the strongest acid blockers for two years or more had a 65 percent increased risk for becoming B12 deficient. Why the association?

B12 is a vitamin whose fancy scientific name is cobalamin. It's found only in eggs, meat, poultry, and fish, and it's kind of a high-maintenance vitamin: If it doesn't get special attention, it refuses on moral and ethical grounds to be absorbed into the body. Acid and stomach enzymes liberate the B12 from that chicken quesadilla you just ate, and then the B12 needs to bind to a special protein secreted by the stomach. That special protein -- "intrinsic factor" -- acts as the V.I.V. (Very Important Vitamin) pass that allows the B12 to get absorbed into the small intestine.

And that's good because B12 teams up with another vitamin, folate, to help synthesize DNA (amongst other things). If we are low on B12, our body will have a hard time making enough red blood cells to keep up with the ones that are naturally wearing out, and we will become anemic. This is termed megaloblastic anemia because the red blood cells that are produced are "megalo" meaning large, as in "megalomaniac." The anemia will leave you weak and sapped of energy, but low B12 levels can also cause nerves to dysfunction, leading to symptoms like numbness or buzzing feelings, wobbly walking, or even wobbly thinking, e.g., dementia.

B12 deficiency can develop when the stomach loses the ability to make intrinsic factor. This is termed "pernicious anemia" and is most common in (but not limited to) people of Northern European ancestry. But B12 deficiency can also develop in patients with low levels of stomach acid: older folks whose stomach is just wearing out, patients who've had gastric bypass weight loss surgery, or in the millions of people who are on acid-blocking medications.

The most powerful antacids are called "proton-pump inhibitors" (PPIs) and include familiar names like omeprazole, Prevacid, Prilosec, Aciphex, Protonix. According to a 2010 article in the Archives of Internal Medicine, PPIs are the third-highest selling drug category in the United States, accounting for more than 113 million prescriptions annually with sales of nearly $14 billion (157 million prescriptions were filled in 2012). The article points out that while PPIs appear safe in the short term, patients often continue therapy for extended durations without an end point. Studies have found that in 50 to 70 percent of cases, PPIs are being used for unapproved, sketchier indications, or in situations where non-pharmacological measures might do the trick.

With "something-for-nothing" science, you can turn off the acidity of the stomach and nothing untoward happens, but of course, in reality the acidity wasn't a mistake. It may well have provided a cauldron of death to the bacterially-contaminated foods we routinely ingested before we believed in the Germ Theory or basic sanitation (how long would the Jamestown settlers have lasted if they'd been taking omeprazole, a few weeks?). Food poisoning is much less of an issue today, but acid suppression still seems to increase the chance of some infections like diarrhea and even pneumonia. It's also been associated with iron deficiency, and with an increase in fractures in postmenopausal women.

Yes, antacid medications have brought heartburn relief and ulcer healing to millions of people, but changing the acidity of the stomach does invite other, sometimes serious medical problems. That's real world, something-for-something science.