Bioavailability and pharmacokinetics of (poly)phenols following consumption of selected blueberries and a blueberry-rich protein bar by adult males and females: a randomized, crossover, controlled trial

Abstract

Background

It is commonly believed that higher nutrient content equates to healthier foods and that food processing lowers nutrient content, although bioavailability studies often indicate otherwise. Blueberries, a rich source of (poly)phenols with proven health benefits, provide a feasible model to evaluate phytochemical bioavailability following consumption of raw and processed fruits.

Objectives

This study evaluates the effect of processing on the bioavailability of (poly)phenols following consumption of 4 interventions: 2 blueberry varieties (i.e., Elliott and Olympia) selected based on differing (poly)phenol content and in vitro bioaccessibility, a (poly)phenol-rich protein bar providing an equivalent amount of blueberries, and a control beverage.

Methods

This blinded, randomized, 4-way crossover, controlled trial (n = 18; 42.06 ± 12.53 y; body mass index [BMI] 24.75 ± 2.97 kg/m²) fed 1 serving (150 g) of Elliott and Olympia blueberries and a (poly)phenol-rich protein bar containing 1 serving of Elliott blueberries, compared with a macronutrient-matched control beverage. (Poly)phenols and metabolites were analyzed in blood and urine over 48 h, with bioavailability and pharmacokinetics assessed via linear mixed-effects repeated measures ANOVA.

Results

Recovery of metabolites was similar following consumption of blueberry varieties of differing (poly)phenol composition, with higher total urinary recovery after Elliott blueberry relative to Olympia blueberry and protein bar (21% and 29%, respectively). Serum AUC was similar across berry-derived treatments, whereas differences in maximum concentration (C_max) and time at maximum concentration (T_max) were observed; for example, urinary recovery of 3-methoxycinnamic acid-4-O-glucuronide was similar following Elliott blueberry and protein bar (P = 1.00), whereas C_max was 1.24 h later after Elliott blueberry compared with protein bar (T_max = 3.84 compared with 2.60 h). Alternatively, C_max for 3-(3-hydroxyphenyl)propanoic acid was higher following Elliott blueberry compared with Olympia blueberry and protein bar (26.63 and 25.32 ng/mL higher, respectively).

Conclusions

Differing berry (poly)phenol content and bioaccessibility only minimally affect bioavailability following consumption of blueberries relative to a blueberry-rich protein bar, suggesting (poly)phenol-dense foods, such as bars and snacks, could provide similar health benefits as raw fruits. Further studies using other crops are required to assess if these findings are translatable.

This trial was registered at clinicaltrials.gov as NCT04175106.