The Expanding Power of Probiotics and Prebiotics in Overall Health

Growing scientific evidence shows that the gut microbiome, a complex and diverse ecosystem, plays a fundamental role in human health by influencing numerous physiological systems.^1,2 When the gut microbiome is balanced, it supports metabolic regulation, immune function, and gastrointestinal stability. However, disruptions in its composition and activity, known as microbial dysbiosis, are strongly correlated with health-related complications, including gastrointestinal, metabolic, immunological, and neurological diseases.^1,2

Probiotic supplements are frequently used to restore and/or maintain a healthy gut microbiome, particularly when microbial balance is disrupted by antimicrobial therapy, illness, or dietary factors.³ Emerging evidence also supports their use in immune regulation, urogenital health, and adjunctive therapy for conditions influenced by microbiome‑immune interactions.

Prebiotic vs Probiotic

According to the International Scientific Association for Probiotics and Prebiotics (ISAPP), the definitions of a probiotic and a prebiotic are as follows^4,5:

• A probiotic is a live microorganism that, when administered in adequate amounts, confers a health benefit.
• A prebiotic is a substrate that is selectively utilized by host microorganisms, conferring a health benefit on the host.

The ISAPP notes that the health benefits of certain probiotic strains may arise from their ability to influence the composition or activity of the gut microbiota, whereas prebiotics, by definition, exert their beneficial effects through targeted modulation of the gut microbial community.⁴ The use of probiotic supplements continues to gain popularity due to their easy accessibility, perceived safety, and consumer confidence that they promote gut health.⁵

Data published in the American Journal of Pharmacotherapy and Pharmaceutical Sciences indicate that an estimated 33.3% of survey respondents reported taking or having taken probiotics daily, and an additional 29% indicated considering future use. Among daily users, 64% were taking probiotics without guidance from a health care provider, and only 6% sought counseling from a pharmacist when selecting OTC supplements.⁶

Key Benefits of Prebiotics and Probiotics

Research has shown that probiotics provide several clinically meaningful benefits, including support for digestive function, modulation of immune activity, and maintenance of a diverse and balanced gut microbiota, an indicator of overall health. Specific strains have demonstrated efficacy in reducing the duration and severity of diarrhea, improving symptoms such as bloating and abdominal discomfort, and enhancing mucosal immune defenses. Probiotics may also influence systemic health by reducing inflammatory markers and improving certain metabolic parameters through gut‑mediated mechanisms, including short‑chain fatty acid production and interactions along the gut-brain axis.^3,7-9

In addition to aiding digestion, probiotics play another essential role by promoting a healthy immune system and preventing chronic diseases. Research shows that probiotics can provide protective effects in the treatment and prevention of conditions such as gastrointestinal tract infections, irritable bowel syndrome, lactose intolerance, allergies, cystic fibrosis, urogenital infections, diarrhea, hyperlipidemia, eczema, and certain cancers. Probiotics may also support dental health by helping treat and prevent tooth decay and periodontal disease.^4-9

The ISAPP indicates that prebiotics selectively nourish beneficial gut microbes, improving digestive regularity, boosting short‑chain fatty acid production, strengthening the gut barrier, supporting immune function, and helping maintain a resilient, balanced microbiome that benefits overall metabolic health and provides anti-inflammatory benefits.^4,9

Types of Supplements

The National Institutes of Health (NIH) Office of Dietary Supplements says that “probiotics are identified by their genus, species, and strain designation; some probiotics also receive subspecies names.” In addition, “probiotic products often contain microbial organisms from the genera Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus and from the family Lactobacillaceae.”¹⁰

The Lactobacillus genus, including Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, and Lactobacillus plantarum; and the Bifidobacterium genus, including Bifidobacterium longum and Bifidobacterium breve, are some of the most-researched probiotics.^9-11

Probiotic supplements are available for adults and pediatric patients in various dosage forms, including capsules, gummies, chewable tablets, and powders, and some are also formulated in combination with prebiotics.¹⁰ Some supplements are formulated for specific needs to support digestive health and metabolic/weight support, immune health, women’s health, and men’s health.

The Role of the Pharmacist

Pharmacists can assist patients in selecting the appropriate OTC probiotic by aligning specific strains and dosages with patients' needs and by evaluating safety considerations, such as immune status, medical history, potential contraindications, and drug/supplement interactions. Pharmacists can also provide education regarding proper usage, including timing, anticipated benefits, and potential adverse effects. By providing evidence-based guidance, pharmacists can ensure that probiotics are used safely and effectively, with realistic expectations.

Patients, especially those with medical conditions, should consult their health care provider before initiating supplements. Pregnant or breastfeeding women should also seek medical advice to ascertain appropriateness, although no harmful effects have been reported in late pregnancy or lactation. Patients should also be advised to use only reputable brands and adhere to recommended doses.^10-12

According to the National Institutes of Health (NIH) and an International Scientific Association for Probiotics and Prebiotics consensus statement, probiotics should be taken at least 2 hours apart from antibiotics or antifungals. Mild flatulence or bloating may occur but often improves, and gradual dose increases can reduce discomfort. Changes in stool frequency, including loose stools, may occur after initiating probiotics and should be monitored, especially in pediatric patients.^10-12

The NIH recommends that individuals with weakened immune systems avoid probiotics due to increased infection risk, and that those with serious health conditions be monitored closely while using them.^10-12 During counseling, pharmacists can recommend adopting supportive habits, such as balanced nutrition and adequate fiber, to optimize results.^9-12

REFERENCES

1. Levy M, Kolodziejczyk AA, Thaiss CA, Elinav E. Dysbiosis and the immune system. Nat Rev Immunol. 2017;17(4):219-232. doi:10.1038/nri.2017.7

2. Ma ZF, Lee YY. The role of the gut microbiota in health, diet, and disease with a focus on obesity. Foods. 2025;14(3):492. doi:10.3390/foods14030492

3. Sanders ME, Merenstein DJ, Reid G, Gibson GR, Rastall RA. Probiotics and prebiotics in intestinal health and disease: from biology to the clinic. Nat Rev Gastroenterol Hepatol. 2019;16(10):605-616. doi:10.1038/s41575-019-0173-3

4. Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017;14(8):491-502. doi:10.1038/nrgastro.2017.75

5. Probiotics, prebiotics, synbiotics, postbiotics, and fermented foods defined. ISAPP. 2024. Accessed May 5, 2026. https://isappscience.org/wp-content/uploads/2021/07/DefinitionsInfographic.pdf

6. Ozdener-Poyraz AE, Rivkin A, Iwuchukwu OF, Cassino D. Bridging the gap between evidence-based practice and probiotic utilization among US adults: results from a national survey. Am J Pharmacother Pharm Sci. 2022;5:1-21. doi:10.25259/AJPPS_5_2022

7. Ford AC, Harris LA, Lacy BE, Quigley EMM, Moayyedi P. Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndrome. Aliment Pharmacol Ther. 2018;48(10):1044-1060. doi:10.1111/apt.15001

8. Cryan JF, O’Riordan KJ, Cowan CSM, et al. The microbiota-gut-brain axis. Physiol Rev. 2019;99(4):1877-2013. doi:10.1152/physrev.00018.2018

9. Wilhelm S. Prebiotics and probiotics. In: Krinsky D, Berardi R, Ferreri S, et al, eds. Handbook of Nonprescription Drugs. 21st ed. American Pharmacists Association; 2024.

10. Probiotics fact sheet for health professionals. National Institutes of Health Office of Dietary Supplements. Updated March 25, 2025. Accessed May 5, 2026. https://ods.od.nih.gov/factsheets/Probiotics-HealthProfessional/

11. Probiotics. Cleveland Clinic. Updated October 30, 2023. Accessed May 5, 2026. https://my.clevelandclinic.org/health/treatments/14598-probiotics

12. Hill C, Guarner F, Reid G, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol. 2014;11(8):506-514. doi:10.1038/nrgastro.2014.66