Apple Polyphenols and Defecation in Overweight Adults with Constipation – A Randomized Controlled Trial

Constipation is a prevalent symptom in adults and has been linked to an increased risk of serious complications, including cardiovascular and renal diseases. This study evaluated the effect of apple polyphenols on defecation among Japanese adults with a body mass index of ≥25 kg/m2 and 2 experiencing constipation who were otherwise healthy. After screening for eligibility, 24 participants were randomly assigned to either the Apple polyphenol or Placebo group in equal numbers. Participants consumed four tablets/day of either unripe apple-derived polyphenols (600 mg/day) or a placebo after breakfast with water for 12 wk. The primary outcome was weekly defecation frequency. Secondary outcomes included the number of days with defecation, the volume and feeling of defecation, the shape and smell of stools, fecal Akkermansia muciniphila counts, physical measurements, body composition, and blood lipid profile. The analysis included 12 participants in the Apple polyphenol and 11 in the Placebo group. After the 12-week intervention, the Apple polyphenol group had a significantly higher weekly defecation frequency versus the Placebo group (7.0 ± 2.1 vs. 4.9 ± 1.4 times; group difference: 2.2 times [95% CI 0.8–3.6], p = 0.004). No significant inter-group differences were observed in fecal A. muciniphila counts, physical measurements, body composition. While blood triglyceride levels tended to be lower in the Apple polyphenol group. These findings suggest that the consumption of polyphenols derived from immature apples may increase defecation frequency and ameliorate constipation; however, it appears not to affect A. muciniphila. Clinical trial registry: UMIN000050393.