A new study is turning the conventional thinking about the benefits of probiotics for IBS relief upside down. Everyone has large numbers of bacteria living inside their digestive tract. In fact, you have 10 times more bacteria cells in your body than all other cells combined. And though no one knows for sure what causes irritable bowel syndrome (IBS) symptoms like belly pain, cramping, constipation or diarrhea, one theory is that symptoms are caused by an overgrowth of harmful bacteria.
Probiotics, on the other hand, are considered good bacteria, and the theory on probiotics was that by adding lots of good bacteria to your digestive system—either with a supplement or simply by eating foods rich in probiotics, like yogurt—you could reduce the number of harmful bacteria and in turn help control symptoms of IBS. As long as both theories were correct.
“IBS may be caused by changes in normal bacteria of the gut," said Maged Rizk, M.D., a gastroenterologist and director of the Chronic Abdominal Pain Center at the Cleveland Clinic in Ohio. "These changes may cause the gut to be hypersensitive and affect the way the gut functions, causing symptoms of IBS. But that’s still just a hypothesis. We don’t know the exact cause of IBS yet."
A review of research on probiotics, published in the journal Gut in 2010, suggested that probiotics are more than just a myth, but not by much. Scientists reviewed 19 clinical trials involving 1,650 people that compared the use of probiotics to the use of a placebo in people with IBS. They concluded that probiotics appeared to have some benefit over placebo, but the amount of benefit was uncertain, and so was the best type of probiotic to take.
There are two main types of probiotics. Some studies have suggested that the best type for IBS is Bifidobacteria, as long as you take it in large enough amounts. The other main type is called Lactobacillus. “Bifidobacteria is the one usually found in supplements," said Dr. Rizk. "Lactobacillus is the one usually found in yogurt."
More recent research published in the journal BMC Gastroenterology in 2013 suggests that the benefits of probiotics for IBS may lean more toward the side of myth. In this study of 76 people with IBS, half consumed a dairy product with probiotics twice a day, while the others consumed one without probiotics twice a day. After four weeks, IBS symptoms had improved in 57% of the probiotics group and 53% of the non-probiotics group; after eight weeks, improvement in IBS symptoms was recorded for 46% of the probiotics group and 68% of the others—leading the researchers to conclude that probiotics were no better than non-probiotics for IBS.
Until more studies have been done, the jury is still out on what if any benefit probiotics offer people with IBS. What is known, though, is that the FDA has not approved use of probiotics as a treatment for any disease. So far, other than increased gas, studies have not found any significant side effects from probiotics, but you should still talk to your doctor before starting on them, especially if you're pregnant or have any serious health condition, or if you're thinking of giving them to a child. Whether consumption of probiotics has any long-term side effects has not been determined.
“It is not surprising that about 50% of people with IBS get better with either a placebo or probiotics," Rizk said. "There is a strong connection between the brain and the gut." Noting that he had not seen adverse effects from their use, "probiotics are worth a try,” he said.
But are they myth or medicine? Nobody can say for sure yet. But if you're interested in giving probiotics a try, and your doctor gives you the nod, you might start by eating yogurt with active probiotic cultures a few times a day or by taking a probiotic supplement in pill or powdered form. Until research has revealed more about the causes of IBS and the effects of probiotics, you'll be conducting your own informal clinical trial to see if probiotics work for you.
By Chris Iliades, M.D.