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Prescription antacids associated with increased risk of allergies
The taking of prescribed stomach acid-reducing medications is associated with an increase in the risk of developing allergies, according to an analysis of over 8 million health records from Austria published in Nature Communications. The findings provide a real-world validation of previous experimental observations.
The immune system is normally tolerant to molecules derived from food and the environment but can become hypersensitive to them in some people, causing allergies. It is currently unclear how hypersensitivity develops, but an increase in allergic diseases in developed countries suggests that changes in lifestyle may contribute. The acidic environment of the stomach helps break down food-derived proteins into small fragments. Stomach acid inhibitors — commonly used to treat gastric ulcers — can interfere with this food digestion. As a result, larger protein fragments reach the intestine, where they can act on the immune system as proto-allergens.
Erika Jensen-Jarolim and colleagues evaluated how much this process may impact public health. They studied prescription medication records covering 97% of the population of Austria over a four year period (2009–2013), and found that people using prescription gastric acid inhibitors were twice as likely to need an anti-allergy medication in subsequent years. Those taking six daily doses per year were at risk, which increased with more frequent usage. The risk was higher in women, and in older individuals. These findings suggest that the health benefits of gastric acid inhibition must be carefully weighed against potential risks.
Expert Reaction
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Elena Schneider-Futschik is a pharmacist by training and leads the Respiratory Pharmacology Lab at the University of Melbourne, Biochemistry & Pharmacology.
Stomach acid plays an important role in breaking down food and absorbing nutrients, as well as also killing bacteria and microbes.
Long-term use of stomach acid inhibitors, used to treat heartburn, reflux or stomach ulcers, disrupt these processes and interfere with food digestion.
This results in larger proteins getting through the stomach to the intestine where they overstimulate the immune system, which has been shown in previous animal studies and a small group of patients.
For the first time, the authors of this study investigated how much this process actually affects the population by accessing the public health record of almost all Austrians over a 5-year period.
They found that the more often you take stomach acid inhibitors the more likely you are to develop allergies; women are particularly at risk.
Needlessly said, certain people with certain medical conditions need their appropriate therapy for long-term acid suppression, but the majority of people with heartburn and reflux should not be using these drugs long-term.
An interesting retrospective study showing that subjects taking long term gastric acid suppressant medications were approximately twice as likely to subsequently take anti-allergy medications.
This effect seen with long term gastric acid suppressant medications was stronger in women than in men.
As always, data from non-controlled retrospective studies needs to be treated with caution, as it cannot be used to establish a causal link.
Nevertheless, this study highlights the extremely large percentage of the population taking such gastric acid suppressant medication, raising the question of whether these medications are being overused.
The association was seen with courses of gastric acid suppressant medication as short as six days, which implies if this effect is real then it must be able to work extremely fast.
As the postulated mechanism is the prevention of breakdown of allergens in food in the absence of gastric acid, it might be expected that the increase in allergies should be restricted to oral allergies, such as nuts or shell fish, and not other allergies, such as to insect stings or aero-allergens.
Unfortunately this study was unable to extract such data, with this being a major limitation in its design.
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