Effects of Chokeberry Juice Added to a Mediterranean-Style Diet on Glycemic Control and Redox Homeostasis in Women with Prediabetes: A Randomized Controlled Trial.

Background

Prediabetes is characterized by impaired glucose regulation and altered redox homeostasis, which may contribute to progression to type 2 diabetes. Polyphenol-rich foods may improve metabolic and redox balance.

Methods

Fifty-four women aged 30-60 years with prediabetes were randomly assigned to an intervention group (IG) or control group (CG); 50 completed the 12-week study (25 per group). Both groups received Mediterranean diet recommendations. The IG additionally consumed 100 mL/day of chokeberry juice, providing 457 mg GAE of total polyphenols and 9.7 mmol antioxidant capacity (FRAP), whereas the CG received no study product. Fasting plasma glucose (FG), HbA1c, 2 h plasma glucose (2h-PG), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were assessed at baseline and 12 weeks. Between-group differences in individual changes were analyzed using the Mann-Whitney U test with Benjamini-Hochberg false discovery rate correction. The randomized substudy reported here was conducted within the broader single-group parent study registered at ClinicalTrials.gov (NCT06435130), which enrolled a larger mixed-sex cohort; the present analysis concerns only the nested 12-week randomized comparison in women with prediabetes.

Results

Compared with the CG, the IG showed greater reductions in FG, HbA1c, 2h-PG, TOS, and OSI and a greater increase in TAS. All between-group differences remained significant after FDR correction (adjusted p < 0.001), with large Cliff's delta values.

Conclusions

Adding 100 mL/day of chokeberry juice to Mediterranean diet recommendations for 12 weeks was associated with modest but statistically significant improvements in glycemic and redox-related outcomes in women with prediabetes. The small sample, short follow-up, and lack of placebo control limit generalizability; larger, longer placebo-controlled trials are warranted.