An 8-week freeze-dried blueberry supplement impacts immune-related pathways: a randomized, double-blind placebo-controlled trial

Abstract

Background Blueberries contain high levels of polyphenolic compounds with high in vitro antioxidant capacities. Their consumption has been associated with improved vascular and metabolic health. Purpose The objective was to examine the effects of blueberry supplement consumption on metabolic syndrome (MetS) parameters and potential underlying mechanisms of action. Methods A randomized double-blind placebo-controlled intervention trial was conducted in adults at risk of developing MetS. Participants consumed 50 g daily of either a freeze-dried highbush blueberry powder (BBP) or a placebo powder for 8 weeks (n = 49). MetS phenotypes were assessed at weeks 0, 4 and 8. Fasting blood gene expression profiles and plasma metabolomic profiles were examined at baseline and week 8 to assess metabolic changes occurring in response to the BBP. A per-protocol analysis was used. Results A significant treatment effect was observed for plasma triglyceride levels that was no longer significant after further adjustments for age, sex, BMI and baseline values. In addition, the treatment*time interactions were non-significant therefore suggesting that compared with the placebo, BBP had no statistically significant effect on body weight, blood pressure, fasting plasma lipid, insulin and glucose levels, insulin resistance (or sensitivity) or glycated hemoglobin concentrations. There were significant changes in the expression of 49 genes and in the abundance of 35 metabolites following BBP consumption. Differentially regulated genes were clustered in immune-related pathways. Conclusion An 8-week BBP intervention did not significantly improve traditional markers of cardiometabolic health in adults at risk of developing MetS. However, changes in gene expression and metabolite abundance suggest that clinically significant cardiometabolic changes could take longer than 8 weeks to present and/or could result from whole blueberry consumption or a higher dosage. BBP may also have an effect on factors such as immunity even within a shorter 8-week timeframe. Clinical trial registration clinicaltrials.gov, NCT03266055, 2017

Fruit and Vegetable Supplemented Diet Modulates the Pig Transcriptome and Microbiome after a Two-Week Feeding Intervention

“…In support of our observations, a polyphenol-rich variety of apples provided in the diet to healthy adults was also shown to induce changes in peripheral blood mononuclear cells (PBMC) gene expression with differential regulation of immunoglobulin-related genes that had roles in immunoglobulin production and B-cell mediated immunity [75]. Significant changes in the expression of genes associated with immune-related pathways were also detected in adults at risk of developing metabolic syndrome who received a freeze-dried blueberrysupplemented diet [76], thus demonstrating that controlled nutritional interventions have the potential to affect health through immune response modulation. However, more studies with larger sample numbers are needed to explain the molecular mechanism of action of different FV-enriched diets and its regulation of inflammation on metabolic diseases.…”

Impact of Blueberry Consumption on the Human Fecal Bileacidome: A Pilot Study

“…Samples analysed in this study were originally collected from volunteers of a randomized, double-blind, placebo-controlled trial measuring the impact of BBP supplementation on immune related pathways (see reference [18]). Briefly, the original study was conducted between 2017 and 2019 at the Institute of Nutrition and Functional Foods (INAF) of Université Laval in the Quebec City area (Canada).…”

“…From the 49 participants involved in the original trial [18] only those from the intervention group were selected for the present proof of concept study on bile acids. A sample from one participant in the BBP group could not be used as it was in insufficient quantity to be profiled for BAs.…”

“…In sum, the final cohort involved in the present investigations comprised 24 Caucasian individuals (11 men and 13 premenopausal, non-pregnant and nonlactating women) of the BBP intervention group that are at risk of metabolic syndrome (Table 1). As extensively described in Rousseau M. and colleagues [18], inclusion criteria were a BMI of 25.0-40.0 kg/m 2 or abdominal obesity (waist circumference ≥ 94 cm for men and ≥ 80 cm for women); triglycerides ≥ 1.35. mmol/L or fasting insulin concentration ≥ 42 pmol/L [19]. Participants were excluded if, prior to the study, they were diagnosed with diabetes, hypercholesterolemia, or hypertension, and if they were taking medications for these conditions.…”

“…Participants were excluded if, prior to the study, they were diagnosed with diabetes, hypercholesterolemia, or hypertension, and if they were taking medications for these conditions. Participants were also excluded if they took antibiotics during of up to months before the study [18].…”