Probiotics are live microorganisms that might be beneficial in certain instances when consumed. Proponents believe the bacteria can help maintain good health and treat various ailments. Probiotics are available in many forms, including pills, juice, sausage, cookies, and even cosmetics.

However, the science shows that while probiotics may hold some promise and seem to be effective for certain conditions, the health claims have largely been exaggerated. Since producers market them as supplements, attribute only vague health claims to them, and never state they can treat or cure disease, the FDA has no authority over them.

Probiotic love is the reverse of gluten hysteria. Because celiac sufferers should avoid gluten, the idea got out there that we should all do the same. Conversely, probiotics’ limited ability has been touted as a cure-all for the masses. This is a microcosm of an anti-science sentiment that will dismiss the success of antibiotics, vaccines, statins, and GMOs, while giving false credit to Reiki, wheatgrass juice, colloidal silver, and organic produce.

Concerning microbe-based treatments, the majority of studies have failed to reveal any benefit for healthy individuals. The bacteria seems to help only those suffering from specific intestinal disorders, such as irritable bowel syndrome, acute diarrhea, peptic ulcers, and necrotizing enterocolitis, which is a bowel disease that afflicts premature babies. These are welcome results, but microbiologists caution that a promising study on a single strain of a particular species of bacteria should not be taken as proof that all probiotics work for all conditions in all people. Like most medicine, a probiotic treatment plan should be tailored for individual needs.

That’s not what is happening with most probiotic products on the market. In an article for Scientific American, Ferris Jabr wrote that manufacturers often select bacterial strains they know will grow in large numbers as opposed to choosing ones that have known health benefits or that have adapted to the human gastrointestinal system.

Even when probiotic bacteria survive and propagate in the stomach or intestines, there are probably too few of them to affect significant change. Per the SA article, humans’ gastrointestinal tracts contain upwards of 20 trillion bacteria, compared to the relatively paltry 100 million contained in a typical serving of probiotic grape nuts. The article further cited a review of 34 trials that studied whether probiotic supplements changed bacteria diversity in fecal samples. Kudos to the researchers on that project for taking one for Team Science. Only one of the trials revealed a noticeable change and there was no indication this alteration was beneficial.

Scientists have yet to completely understand microbiome function and the impact of probiotics on it. They don’t know how microorganisms in our gut give rise to or affect unpleasant conditions. Nor do they have a proven method for treating unhealthy gastrointestinal tracts. Katherine Hobson, writing for 538, also noted, “We still don’t even know what an ideal gut bacterial mix would look like, if there is such a thing.”

Even with health issues for which probiotics show promise, researchers are still trying to ascertain which ones are best for each condition, which dosage to administer, how long to take them, and which population would benefit. There’s no evidence that healthy persons will gain from taking a daily probiotic supplement. For those persons, the best way to maintain gastrointestinal wellness is through regular consumption of fiber, fruit, and vegetables. That’s all you need, plus you will save money by bypassing the supplement, unless your fruits and veggies are organic.