While probiotics are generally well tolerated, including probiotic-rich foods or adding probiotic supplements might infrequently cause side effects. Although diarrhea is not a typical side effect, probiotics can sometimes cause related symptoms such as abdominal discomfort, bloating or gas. In fact, probiotics are more likely to reduce the duration of diarrhea or prevent antibiotic-related diarrhea. While there are health benefits to having a healthy balance of gut bacteria, always talk to your doctor before using probiotics, to be sure the remedy is appropriate for you.
Probiotics are live microorganisms touted for their health benefits. The bacteria that line your gut influence health and disease risk, and more research is needed to help clarify the role of these microorganisms and to identify the best way to achieve a healthy balance of gut bacteria. Options to enrich your diet with these beneficial bacteria include supplements and probiotic-rich foods such as yogurt, kefir, sauerkraut or other fermented or cultured foods. In addition, choosing a diet rich in whole, unprocessed plants -- fruits, vegetables, nuts, seeds, whole grains and beans -- nourishes and increases healthy gut bacteria, according to research published in the September 2012 "Journal of Agricultural and Food Chemistry." If you are prompted to supplement your diet with probiotics to stay healthy or manage certain conditions, it's wise to understand known benefits, potential side effects and risks.
Role in Gastrointestinal function
According to the National Institutes of Health (NIH), gut bacteria plays a role in digesting food, protecting the body from disease-causing microorganisms, producing certain vitamins and strengthening the immune system. As these bacteria munch on the partially digested food in your gut, they produces gas, just as you do when you eat certain foods. Certain strains may also loosen stools, which is why probiotics are touted to help with constipation. In fact, an analysis of twelve studies published in the August 2014 issue of "American Journal of Clinical Nutrition" linked probiotic use with faster movement of food through the gut, softer stools and more frequent bowel movements. These noted benefits to stool frequency and consistency make diarrhea plausible if large doses are used or with individual tolerance to probiotics.
Probiotics May Counter Diarrhea
Probiotics are more likely to improve acute or short-term diarrhea instead of causing it. A review published in the November 2010 "Cochrane Database of Systematic Reviews" analyzed 63 studies including over 8000 participants, and concluded the use of probiotics in acute diarrhea -- along with the usual rehydration therapy -- reduced the duration of diarrhea by about one day and reduced the frequency of stools by day 2 of probiotic therapy. In addition, an analysis of 23 studies and nearly 4500 participants, published in the May 2013 "Cochrane Database of Systematic Reviews," demonstrated that probiotics taken along with antibiotics reduced risk of developing the particularly dangerous Clostridium difficile-associated diarrhea by 64 percent. More research is needed to understand this complex world of probiotics, including health effects of different species and strains, and how to most effectively alter gut bacteria to optimize health.
Warnings and Precautions
While probiotics could cause cramping, bloating, gas or potentially diarrhea, most people tolerate normal doses without side effects. Furthermore, probiotics may actually reduce the duration of diarrhea, or reduce the risk of diarrhea if taking antibiotics. However, probiotics may lead to infections in people with compromised or underdeveloped immune systems, such as the elderly or infants, and their safety has not been adequately studied in people with medical conditions outside of gastrointestinal disorders. So it's wise to consult your doctor about risks and benefits before starting probiotic supplements.
Reviewed by: Kay Peck, MPH, RD
- U.S. Pharmacist: Utility of Probiotics in Gastrointestinal Disease
- American Journal of Clinical Nutrition: The Effect of Probiotics on Functional Constipation in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
- Cochrane Database of Systematic Reviews: Probiotics for Treating Acute Infectious Diarrhoea
- Asia Pacific Journal of Nutrition: Safety of Probiotics
- National Institutes of Health: National Center for Complementary and Integrative Health: Probiotics In Depth
- Journal of Agricultural and Food Chemistry: Up-Regulating the Human Intestinal Microbiome Using Whole Plant Foods, Polyphenols, and/or Fiber