(P22-017-23) Study Protocol: A Reverse Translational Approach to Understanding the Role of the Gut Microbiome in Blueberry Polyphenol Bioavailability

Objectives: Mounting evidence indicates age-related vascular endothelial dysfunction (VED), characterized by impaired endothelium-dependent dilation, is central to cardiovascular disease pathogenesis. The gut microbiome is the collection of intestinal microorganisms and their genes and has been linked to the development of VED. Accumulating evidence suggests that polyphenols, present in blueberries, exert cardiovascular-protective effects. Polyphenols are secondary plant metabolites, many of which are catabolized by the gut microbiota to metabolites that are released into circulation, where they interact with tissues and organs to exert health effects. Our laboratory demonstrated that daily blueberry consumption for 12 weeks improved VED in postmenopausal women with above-normal blood pressure (BP) in a randomized controlled trial, and that there were increases in several plasma flavonoid and microbial metabolites. We hypothesize the ability of blueberries to improve VED in postmenopausal women with above-normal BP is dependent on the gut microbiota, in part due to their role in metabolizing blueberry polyphenols, and that blueberry polyphenol bioavailability is enhanced over time with daily consumption due to the prebiotic effects of polyphenols.

Methods: Fecal samples collected from our human intervention study pre-blueberry consumption, 12 weeks post-blueberry consumption, and 12 weeks post-placebo consumption were transplanted to 6-week-old germ-free (GF) male C57BL/6 mice, while one GF control group of mice did not receive fecal transplants (total n=20, n=5/group). Six weeks after microbiota colonization, mice were gavaged with 116.1 mg of freeze-dried blueberry powder, and blood was collected after 1 and 6 hours. Using targeted metabolomics, we will quantify 88 plasma polyphenol metabolites to evaluate bioavailability.

Results: N/A - protocol abstract

Conclusions: This study will investigate whether the gut microbiota is critical in determining levels of exposure to blueberry polyphenol metabolites (GF vs. colonized mice) and whether a microbiome that had been pre-conditioned by chronic daily blueberry exposure has a greater capacity to metabolize blueberry components.

Funding Sources: USDA National Institute of Food and Agriculture [grant no. 2020-67017-30833/project accession no. 1021875] and the US Highbush Blueberry Council.