A recent study published in the journal Advances In Nutrition has delved into the evidence surrounding the benefits of probiotics for healthy individuals. Probiotics, defined as microbes that provide health benefits to their host, have been widely studied for their potential to aid various health conditions. However, a persistent question remains: Should everyone, including those who are already healthy, take probiotics?
The research team employed an approach modeled after the United States Preventive Services Task Force (USPSTF), focusing on healthy individuals while also considering specific population subgroups. The study aimed to determine whether probiotics could prevent infections in the vaginal, respiratory, gastrointestinal (GI), or urinary tracts, reduce antibiotic use, or improve cardiovascular risk factors.
Urinary and Vaginal Tract Infections
Urinary tract infections (UTIs) are the most common bacterial infections globally, particularly among females. One trial found that weekly vaginal application of suppositories containing Lactocaseibacillus rhamnosus GR-1 and Limosilactobacillus fermentum B-54 for one year significantly reduced UTI recurrence. Similarly, young women with a history of recurrent UTIs who took Lactobacillus crispatus CTV-05 experienced fewer episodes compared to those who received a placebo. Additionally, oral administration of Lactobacillus reuteri RC-14 and Lacticaseibacillus rhamnosus GR-1 reduced UTI recurrence rates compared to antibiotic therapy.
For vaginal tract infections, characterized by disruptions in normal microbiota due to pathogens, probiotics have shown potential in replenishing beneficial lactobacilli. One trial involving women with bacterial vaginosis (BV) treated with vaginally administered Lactobacillus crispatus IP 174178 capsules showed a reduction in BV recurrence. Another study found that intravaginal capsules of Streptococcus thermophilus, Lactobacillus acidophilus, or Lacticaseibacillus rhamnosus led to lower BV recurrence rates compared to a placebo.
Respiratory and GI Tract Infections
Probiotic research has extensively explored their role in preventing antibiotic-associated diarrhea (AAD), a common side effect of antibiotic use. Various systematic reviews and meta-analyses have indicated that probiotics can reduce the risk of AAD by up to 37%. Probiotics such as Lacticaseibacillus rhamnosus GG and Saccharomyces boulardii have shown significant effectiveness compared to placebo or no intervention.
Travelers’ diarrhea (TD), a frequent issue for those traveling from developed to less-developed regions, has also been a focus. A systematic review found that both probiotics and rifaximin reduced the incidence of TD, with rifaximin proving more effective.
Regarding respiratory tract infections (RTIs), clinical studies involving thousands of healthy adults and children have consistently shown that probiotics decrease the risk and incidence of RTIs.
Cardiovascular Health
Cardiovascular disease (CVD) remains the leading cause of death globally. While long-term studies on probiotics for CVD prevention are lacking, research has investigated their impact on cardiovascular risk factors such as obesity, hypertension, and glucose metabolism. One study highlighted that probiotics slightly but consistently improved multiple metabolic risk factors related to non-alcoholic fatty liver disease, obesity, and diabetes. Additionally, supplementation with probiotics or synbiotics (a combination of prebiotics and probiotics) led to reductions in total cholesterol levels among individuals with metabolic syndrome.
A meta-analysis further supported these findings, showing that synbiotics increased high-density lipoprotein cholesterol levels and reduced serum insulin, low-density lipoprotein cholesterol, total cholesterol, triglycerides, systolic blood pressure, body weight, and waist circumference. These results were both statistically significant and clinically relevant.
Concluding Remarks
The study concludes that while the current evidence is insufficient to make broad preventive recommendations for probiotic use in healthy individuals, this does not imply that probiotics lack efficacy. The research on probiotics is still relatively nascent, and the absence of conclusive evidence underscores the need for further studies. Despite this, the review provides a compelling foundation for future research and potential funding in the field of probiotics.
Journal Reference: Merenstein DJ, Tancredi DJ, Karl JP, et al. Is there evidence to support probiotic use for healthy people? Advances in Nutrition, 2024, DOI: 10.1016/j.advnut.2024.100265, ScienceDirect.