Probiotics have gained increasing clinical attention as adjunctive treatment for lower gastrointestinal disorders. However, evidence supporting their therapeutic efficacy remains limited, particularly with regard to sex-related differences. This expert review provides evidence-based insights and practical recommendations for the use of probiotics in patients with irritable bowel syndrome (IBS), functional constipation (FC), and Clostridioides difficile infection (CDI), considering possible sex-related differences. Evidence from randomized controlled trials and meta-analyses indicates that probiotics can modestly improve global symptoms, abdominal pain, and bloating in IBS and enhance bowel movement frequency and stool consistency in FC. However, these effects are strain-specific and heterogeneous. Although clinical studies on probiotics in IBS have not confirmed significant sex-related differences, experimental animal studies using stress-induced IBS models have demonstrated sex-dependent responses to specific probiotic strains, supporting the biological plausibility of such differences. For CDI, the efficacy of probiotics in preventing primary or recurrent infections remains inconsistent across large trials, and current guidelines usually do not recommend their routine use. However, sex- and age-related immunologic differences support the clinical differences of CDI. Probiotics are generally considered safe for healthy individuals, although caution is advised in patients who are immunocompromised or critically ill. Clinicians should select probiotic products based on strain-specific clinical evidence, adequate viable doses, patient characteristics and sex. In conclusion, probiotics might play a role as adjunctive therapy for IBS and FC, with variability in responses influenced by microbial, host, and potential sex-related factors. Further research is needed to establish optimized personalized probiotic strategies.

Objectives: Gastric cancer (GC) demonstrates a sex disparity that may also be associated with body mass index (BMI). This study explored whether the effect of BMI on the risk of GC varies by sex.

Methods: The study cohort included 341,999 Koreans aged 40 years or older from the National Health Insurance Service–Health Screening Cohort, with a median follow-up period of 10 years. Participants were categorized into five groups based on their BMI. The effect of BMI was evaluated using Cox proportional hazard regression. Additionally, stratification analysis was performed according to waist circumference.

Results: An increased risk of developing GC was observed across the study population among those with obesity (BMI 25.0–29.9 kg/m²; hazard ratio [HR], 1.11; 95% CI , 1.03–1.20) and severe obesity (BMI ≥30.0 kg/m²; HR, 1.22; 95% CI, 1.01–1.47), considering a 2-year latency period. Notably, the rise in GC risk was particularly pronounced among women with obesity and men with severe obesity. In the age-stratified analysis, severe obesity (BMI ≥30.0 kg/m²) was associated with an increased risk of GC in men under 50 years old (HR, 1.83; 95% CI, 0.99–3.37). For individuals aged ≥50 years, obesity was linked to a heightened risk of GC in both sexes. Furthermore, normal BMI (18.5–22.9 kg/m²) was associated with an increased GC risk in women.

Conclusion: These findings indicate a positive association between excess body weight and the risk of GC in Koreans, particularly among men with severe obesity.

Citations

• Sex- and Subsite-Specific Links between Adiposity and Gastric Cancer: Beyond Body Mass Index Alone
  Seung-Joo Nam
  Gut and Liver.2026; 20(2): 161.     CrossRef
• Gender equity in medicine, artificial intelligence, and other articles in this issue
  Sun Huh
  The Ewha Medical Journal.2024;[Epub]     CrossRef