A newly released study in The Journal of Nutrition shows that regular intake of phenol-rich raspberries and a fructo-oligosaccharide prebiotic regimen improved the composition of the gut microbiota, particularly in individuals with pre-diabetes.

Diet plays an important role in shaping the composition and function of the gut microbiota. Fruits such as red raspberries that are rich in phenolic compounds have been shown to modulate the gut microbiota and to benefit cardiometabolic health. In addition, fermentable carbohydrate fiber sources such as fructo-oligosaccharides that are resistant to human digestion are also beneficial to human health. Previous studies have shown that consuming red raspberries promotes favorable changes in the gut microbiome, which in turn improves postprandial glycemia in individuals with type 2 diabetes.  However, it remains unclear if fructo-oligosaccharides can augment the metabolic effects of red raspberries.

To bridge this knowledge gap, Britt Burton-Freeman (Illinois Institute of Technology) and colleagues investigated whether supplementation with phenolic-rich red raspberries, alone or with a fructo-oligosaccharide prebiotic, would improve biomarkers of cardiometabolic risk and whether the effects were related to modulation of the gut microbiota.   

Healthy adults and those with pre-diabetes participated in a randomized crossover trial with two 4-week supplementation periods.  Subjects consumed either 125 g (~ 1 cup) of red raspberries daily or a combination of red raspberries plus 8 g of fructo-oligosaccharides daily. Each period was separated by a 4-week washout.

Regular intake of phenol-rich red raspberries and a fructo-oligosaccharides prebiotic improved cardiometabolic risk factors as well as the composition of the gut microbiota, particularly in individuals with pre-diabetes. The combination of red raspberries and fructo-oligosaccharides enriched the post-intervention gut microbial community by facilitating the growth of beneficial bacteria and suppressed those considered to be unfavorable. This low-calorie dietary strategy improves the gut microbiota composition and function in individuals with pre-diabetes and results in significant improvements in metabolic health.


Xuhuiqun Zhang, Anqi Zhao, Amandeep K Sandhu, Indika Edirisinghe, Britt M Burton-Freeman, Red Raspberry and Fructo-Oligosaccharide Supplementation, Metabolic Biomarkers, and the Gut Microbiota in Adults with Prediabetes: A Randomized Crossover Clinical Trial, The Journal of Nutrition, Volume 152, Issue 6, June 2022, Pages 1438–1449, https://doi.org/10.1093/jn/nxac037.

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