What are probiotics?
Probiotics are live microorganisms that provide health benefits when consumed or applied to the body. They are commonly found in foods like yogurt and other fermented products, as well as in dietary supplements and skincare items. However, there have been reports of serious, sometimes fatal, infections in premature infants given probiotics, prompting the U.S. Food and Drug Administration (FDA) to caution healthcare providers about potential risks.
While bacteria and other microbes are often seen as harmful “germs,” many actually play beneficial roles. Certain bacteria aid digestion, combat disease-causing organisms, and produce essential vitamins. Many of the microbes used in probiotic products are the same or similar to those naturally residing in the human body.
What types of bacteria are found in probiotics?
Probiotics typically include a variety of microorganisms. The most common bacterial groups are Lactobacillus and Bifidobacterium. Additionally, some probiotics contain other bacteria or yeasts like Saccharomyces boulardii.
It’s important to note that different strains of probiotics can have distinct effects. For instance, if one Lactobacillus strain helps prevent a certain illness, that doesn’t mean all Lactobacillus strains or Bifidobacterium probiotics will provide the same benefit.
Are prebiotics the same as probiotics?
No. Prebiotics are non-digestible components in food that selectively promote the growth or activity of beneficial microorganisms in the gut.
What are synbiotics?
Synbiotics are products that combine both probiotics and prebiotics.
How common is probiotic use?
According to the 2012 National Health Interview Survey (NHIS), approximately 4 million U.S. adults (about 1.6%) had used probiotics or prebiotics in the previous 30 days. Among adults, these were the third most popular dietary supplements after vitamins and minerals. Probiotic use among adults quadrupled between 2007 and 2012. The survey also found that around 300,000 children aged 4 to 17 (0.5%) had used probiotics or prebiotics during the same period.
How do probiotics work?
Probiotics may benefit the body in various ways, and different types can act differently. They might:
- Support maintaining a balanced community of microorganisms in the body or help restore balance after disruption
- Produce substances with beneficial effects
- Influence the immune system’s response
How are probiotics regulated in the U.S.?
Regulation of probiotics in the United States depends on their intended use and can be complex. The FDA may oversee probiotics as dietary supplements, food ingredients, or drugs.
Most probiotics are marketed as dietary supplements, which do not require FDA approval before sale. Labels on supplements may describe effects on the body’s structure or function without FDA approval but cannot claim to prevent or treat diseases without FDA authorization.
If a probiotic is intended to treat a disease or medical condition, it must undergo rigorous testing in clinical trials to prove its safety and effectiveness and receive FDA approval before it can be marketed as a drug.
Understanding the Microbiome
The microbiome refers to the vast community of microorganisms living on and inside the human body, and it has become a major focus of scientific research. From 2007 to 2016, the National Institutes of Health (NIH) supported the Human Microbiome Project, which mapped the typical bacteria present in and on a healthy human body. This foundational knowledge of a normal microbiome now enables researchers worldwide—many funded by the NIH—to investigate how changes in the microbiome may be linked to various diseases. They are also developing innovative treatments aimed at altering the microbiome to improve health and combat illness.
One key supporter of microbiome research is the National Center for Complementary and Integrative Health (NCCIH). Scientists funded by NCCIH are exploring how food components interact with microorganisms in the digestive system, focusing on how these diet-microbiome interactions might produce substances that benefit overall health.
What Does Science Say About Probiotics’ Effectiveness for Health Conditions?
Extensive research has been conducted on probiotics, but much remains uncertain about their safety and benefits for various health issues.
Probiotics have shown potential in several areas, such as preventing antibiotic-associated diarrhea (including that caused by Clostridium difficile), reducing the risk of necrotizing enterocolitis and sepsis in premature infants, easing infant colic, treating periodontal disease, and helping to induce or maintain remission in ulcerative colitis.
Despite these promising findings, in many cases it’s still unclear which specific probiotics are effective and which are not. Additionally, optimal dosages and the populations most likely to benefit have yet to be determined. Even for the best-studied conditions, researchers continue to explore these important questions.
Can Probiotics Be Harmful?
Probiotics have a long history of being considered safe, especially for healthy individuals. However, detailed studies on their safety are limited, so there is insufficient data on how often and how severe any side effects might be.
The risk of adverse effects from probiotics is higher in people with serious illnesses or weakened immune systems. For high-risk groups—such as premature infants or critically ill hospital patients—the benefits of probiotics must be carefully weighed against potential risks. There have been reports of severe and even fatal infections in premature infants given probiotics, leading the U.S. Food and Drug Administration (FDA) to alert healthcare providers about these dangers.
Possible harmful effects include infections, production of harmful substances by the probiotic organisms, and the transfer of antibiotic resistance genes from probiotic microbes to other bacteria in the digestive system. Additionally, some probiotic products have been found to contain microorganisms not listed on their labels, and these contaminants may pose serious health risks.
NCCIH-Funded Research
The National Center for Complementary and Integrative Health (NCCIH) supports various research projects related to probiotics and the microbiome. Beyond studies on diet-microbiome interactions, recent investigations include:
- How probiotics might reduce postmenopausal bone loss
- Engineering probiotics to produce natural compounds for microbiome-brain studies
- Understanding how certain probiotics could relieve chronic pelvic pain
- Examining the effects of a specific Bifidobacterium strain on gut short-chain fatty acid production, which may influence antibiotic-associated diarrhea
Additional Considerations
Probiotics should never be used as a substitute for seeking medical care for any health issue. If you’re thinking about taking a probiotic supplement, discuss it with your healthcare provider first—especially if you have existing health conditions. Those with serious illnesses should be closely monitored while using probiotics.
Take control of your health by openly communicating with your healthcare providers about any complementary treatments you use. Together, you can make informed decisions that best support your well-being.