Miryan M, Soleimani D, Alavinejad P, Abbaspour M, Ostadrahimi A. Effects of propolis supplementation on irritable bowel syndrome with constipation (IBS-C) and mixed (IBS-M) stool pattern: A randomized, double-blind clinical trial. Food Sci Nutr. April 20, 2022;10(6):1899-1907. doi: 10.1002/fsn3.2806.

Irritable bowel syndrome (IBS) presents as recurrent abdominal pain and altered bowel function. Its pathophysiology is not well known; however, research shows it may result from disruption of gut microbiota balance, gut-brain axis dysfunction, gut motility and/or permeability issues, and immune dysfunction. Additionally, gastrointestinal (GI) inflammation, psychological stress, chronic infections, genetics, and food choices have been attributed to IBS. Recent studies show that inflammation and oxidative stress play a primary role in diagnosis. Current treatment includes avoidance of gas-producing foods. Propolis is a resin-like substance honeybees make using tree buds, sap, and other botanicals to seal open spaces in beehives. It is rich in polyphenols with secondary metabolites well-known for their antioxidant properties. Propolis has been shown to modulate inflammatory pathways, immune system function, gut microbiota, and GI permeability. The purpose of this double-blind, placebo-controlled clinical trial was to assess the efficacy of propolis on the severity of IBS symptoms.

Participants were recruited between September 2019 and January 2020 from the Soroush Special Clinic of Ahvaz (Ahvaz, Iran). Eligible patients were aged 18 to 65 years; were diagnosed with IBS by a gastroenterologist according to Rome IV criteria; had constipation subtype IBS (IBC-C) or mixed subtype (IBS-M) based on the Bristol stool form scale (BSFS); and were without allergies to bee products. Patients were excluded who were pregnant or breast feeding; had a malignancy, chronic GI disease, or history of GI surgery; used medications that modify GI motility, pre- or probiotics, laxatives, or antibiotics; had a history of psychotherapy drug use; or were currently dieting. Additionally, patients were withdrawn from the study who failed to take ≥ 80% of their supplements, were unwilling to continue, experienced severe physical or mental trauma, or changed diet plan or physical activity during the study period.

Propolis tablets consisted of 450 mg propolis extract (90 mg of polyphenols and 67 mg of flavonoids); the placebo contained micro-crystalline cellulose. Both were manufactured by the Mashhad School of Pharmacy, Mashhad University of Medical Sciences (Mashhad, Iran). Patients were instructed to take one tablet before lunch and dinner (900 mg/day) for six weeks.

A total of 56 participants were evenly randomized to either the propolis group or placebo group. Two in the propolis and three in the placebo discontinued the trial for unrelated reasons. No significant between-group differences were seen at baseline regarding demographics, metabolic equivalent of task (MET), IBS subtypes, disease duration, and anxiety state. No significant changes were observed for mean energy and nutrient intake within or between groups from baseline to culmination. There were no significant changes in weight, body mass index (BMI), waist circumference (WC), or MET values from baseline to culmination within or between groups.

The anxiety score significantly decreased in the propolis group compared to placebo after six weeks (P = 0.04). Overall IBS symptoms and scores significantly decreased in the propolis group following the trial period (P < 0.05). After adjustment of anxiety score as a covariant, significant decreases in mean scores between the two groups were observed for overall IBS symptoms (P = 0.011), severity of abdominal pain (P = 0.004), and frequency of abdominal pain (P = 0.041). In the placebo group, severity of abdominal distension significantly decreased following the trial period (P < 0.05). The percentage of patients achieving a minimum of a one grade deduction in IBS symptoms was significantly higher in the propolis group compared to placebo (P = 0.015), and patients in the propolis group were 6.22 times more likely to realize improvement in IBS symptoms (P = 0.035).

Study strengths included the use of appropriate diagnostic criteria, stratified block randomization, and high compliance rate. Limitations included self-reporting of physical activity and dietary intake, and lack of laboratory biomarkers for IBS. The authors conclude that propolis intake may have beneficial effects on the severity of IBS-M and IBS-C by reducing severity and frequency of abdominal pain. The authors suggest that propolis can be used as adjunctive therapy. Further studies are needed to investigate the effects of propolis supplementation on diarrhea-predominant IBS subtype (IBS-D) and on the gut microbiome of patients diagnosed with IBS.

The authors declare no conflicts of interest.

—Samaara Robbins