The acid in your stomach is impressively strong. Thankfully, your stomach is fine-tuned to deal with it.
However, the rest of your body isn't, so if the acid escapes from your stomach and reaches your esophagus — the tube connecting your stomach to your mouth — it can be painful.
If this happens regularly, doctors call it gastroesophageal reflux disorder, better known as GERD.
Symptoms can include a burning sensation in your chest, trouble swallowing, and regurgitating a sour liquid or food.
GERD affects around 1 in 7 people worldwide. That’s more than 1 billion people.
Many people with GERD can manage it by changing their diets and other lifestyle factors. We’ll outline some strategies for this later on.
These changes alone can make a world of difference for some people. But for others, problems can persist. If this happens, a doctor might prescribe medication.
Some of the most common drugs for GERD are proton pump inhibitors (PPIs). They reduce the amount of acid that the stomach produces, thus reducing the symptoms of GERD.
Because these drugs are often very effective, they are some of the most commonly prescribed drugs in the world. But if you take them for a long time, they can cause issues.
One of stomach acid’s primary roles is protecting you from invasive bacteria. If a would-be attacker enters your nose or mouth, it’s likely to end up in your stomach. Once it's there, your stomach acid makes short work of it.
But if you’re taking PPIs and have less stomach acid, the invader has a better chance of making it to your gut. That’s why people who take PPIs for a long time have a greater risk of developing a Clostridioides difficile, or C. diff., infection.
Also, people taking PPIs have an increased risk of a condition called small intestinal bacterial overgrowth (SIBO).
In a healthy gut, most gut bacteria live in the large intestine. But in people with SIBO, there’s also a large population in the small intestine. This can cause symptoms including bloating, diarrhea, and abdominal discomfort.
So, doctors are keen to find additional ways to help treat GERD. Some researchers think probiotics are worth exploring.
What are probiotics?
Probiotics are live microorganisms that offer health benefits when you consume them.
They're widely available in pills, capsules, and powders, but you'll also find probiotics in foods like live yogurt, kefir, kimchi, and sauerkraut.
The health claims about probiotics — especially supplements — are vast and impressive. But the science behind most of these claims isn't.
Probiotics and GERD
There is evidence that probiotics can influence your gut microbiome in a positive way.
And there’s good evidence that they can help treat antibiotic-associated diarrhea. They might also help if you have some other conditions that affect your gut.
However, at this stage, there’s less evidence that probiotics help with conditions that affect your upper digestive tract — like GERD.
Some scientists have investigated, though. And researchers in Finland published a review in 2020 summarizing some of these findings.
Overall, it was a fairly confusing picture. Probiotics reduced some symptoms of GERD in some cases, but they sometimes had no effect — or even a negative one.
For instance, a few studies reported reduced regurgitation with probiotics, but a few didn’t.
Some found that probiotics significantly reduced acid reflux, others only noted minor improvements in this symptom, and the remainder saw no improvements.
Similarly, for indigestion, some studies concluded that probiotics helped, others found no improvements, and one study found that probiotics made indigestion worse.
However, all things considered, the authors reached some fairly positive conclusions. For instance, in 79% of the comparisons they reviewed, probiotics were linked to reduced symptoms of GERD.
Join the community
Be the first to know about ZOE’s breakthrough research, content from the world’s leading scientists, and more.
But because the studies had been conducted in very different ways, the authors of the review couldn’t combine all the data to do a meta-analysis. And, as they explain, "Only 5 of 14 studies were good quality."
They call for better-designed, randomized, double-blind, placebo-controlled studies with many more participants. In other words, the jury is still out.
Now, let’s ask whether probiotics might help relieve one condition linked to long-term PPI use.
PPIs, probiotics, and SIBO
Earlier, we explained that when people take PPIs for a long time, they have an increased risk of developing SIBO — an overgrowth of bacteria in the small intestine.
There’s some evidence that probiotics might help reduce the risk of developing SIBO in people taking these drugs.
For instance, a study from 2019 recruited children aged 1–18 with GERD. The scientists split the participants into two groups. One took PPIs, and the other took PPIs plus a probiotic — a strain of Lactobacillus reuteri.
They found that children who took the probiotic were less likely to develop SIBO than those who took the PPIs alone.
Another study recruited 134 people with reflux esophagitis who were taking PPIs. The scientists gave some participants probiotics — Bacillus subtilis and Enterococcus faecium — and the others a placebo.
The authors found that people who took probiotics had a lower risk of developing SIBO than those taking a placebo.
And a 2017 review of 22 studies concluded that probiotics could help treat (but not prevent) SIBO. But these studies didn’t focus on people using PPIs specifically.
The challenges of probiotic research
One difficulty of probiotics research is that it’s rarely clear which strains of bacteria you should use in your study.
In your gut microbiome, you have hundreds of species. Deciding which might be best able to help resolve a given health condition is tricky.
So, scientists often try different strains or combinations of strains. And that makes it hard to compare the results of different studies.
As an example, let’s revisit the Finnish review into probiotics and PPIs. The authors of the studies had used an array of probiotics.
Some had looked at single strains of bacteria, including L. gasseri LG21, B. bifidum YIT 10347, and B. lactis HN019.
Others had used a combination of up to six strains of bacteria. And some added other ingredients to their probiotics, including prebiotics, vitamins, and enzymes.
Another challenge of probiotics research is that most gut bacteria aren't easy to grow in a lab. And if you can’t grow them, you can’t turn them into probiotics.
When you see probiotic pills and powders in the grocery store, they contain bacteria that are easy to culture.
And that’s the main reason why the manufacturer chose that strain in the first place — it’s about the ease of manufacture, not the proven health benefits.
That’s not to say that probiotics aren't ever useful. It just means that scientists have their work cut out for them when they try to identify which strains or combinations of strains might work best.
Should you use probiotics to treat GERD?
Right now, the evidence isn’t strong enough for health experts to recommend using probiotics to treat GERD.
Above, we mentioned that making some changes to your diet and lifestyle can really help, so it might be worth trying to:
Cut down on caffeine, alcohol, and soda.
Increase your fiber intake.
Limit your fat intake.
Consider not eating chocolate and peppermint.
Eat fewer spicy foods.
Limit your intake of acidic foods, such as tomatoes.
However, if you want to try probiotics, they seem pretty safe for most people.
While supplements might work for some people, at ZOE, we think that food should come first. And there’s a range of healthy, delicious foods that contain probiotics.
Importantly, you shouldn’t stop taking any medication that a doctor has prescribed before you discuss it with them.
Association between proton pump inhibitor therapy and Clostridium difficile infection in a meta-analysis. Clinical Gastroenterology and Hepatology. (2012). https://www.sciencedirect.com/science/article/abs/pii/S1542356511010780
Beneficial effect of probiotics supplements in reflux esophagitis treated with esomeprazole: A randomized controlled trial. World Journal of Gastroenterology. (2019). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506578/
Does consumption of fermented foods modify the human gut microbiota? The Journal of Nutrition. (2020). https://academic.oup.com/jn/article/150/7/1680/5814068
Gastroesophageal reflux disease and probiotics: A systematic review. Nutrients. (2020). https://www.mdpi.com/2072-6643/12/1/132/htm
Global prevalence and risk factors of gastro-oesophageal reflux disease (GORD): Systematic review with meta-analysis. Scientific Reports. (2022). https://www.nature.com/articles/s41598-020-62795-1
Is it useful to administer probiotics together with proton pump inhibitors in children with gastroesophageal reflux? Journal of Neurogastroenterology and Motility. (2018). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5753903/
Meta-analysis: Proton pump inhibitors moderately increase the risk of small intestinal bacterial overgrowth. Journal of Gastroenterology. (2017). https://link.springer.com/article/10.1007/s00535-017-1371-9
Overprescribing proton pump inhibitors. BMJ. (2008). https://www.bmj.com/content/336/7634/2.short
Probiotics for preventing and treating small intestinal bacterial overgrowth: A meta-analysis and systematic review of current evidence. Journal of Clinical Gastroenterology. (2017). https://pubmed.ncbi.nlm.nih.gov/28267052/
Probiotics for the prevention of antibiotic-associated diarrhea: A systematic review and meta-analysis. BMJ Open. (2021). https://pubmed.ncbi.nlm.nih.gov/34385227/
Probiotics: What you need to know. (2019). https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know
Small intestinal bacterial overgrowth. Gastroenterology and Hepatology. (2002). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099351/
Systematic review: Probiotics in the management of lower gastrointestinal symptoms – an updated evidence-based international consensus. Alimentary Pharmacology and Therapeutics. (2018). https://onlinelibrary.wiley.com/doi/full/10.1111/apt.14539