Probiotics Blunt the Anti-Hypertensive Effect of Blueberry Feeding in Hypertensive Rats without Altering Hippuric Acid Production

PLoS One. 2015 Nov 6;10(11):e0142036. doi: 10.1371/journal.pone.0142036. eCollection 2015.

Abstract

Previously we showed that feeding polyphenol-rich wild blueberries to hypertensive rats lowered systolic blood pressure. Since probiotic bacteria produce bioactive metabolites from berry polyphenols that enhance the health benefits of berry consumption, we hypothesized that adding probiotics to a blueberry-enriched diet would augment the anti-hypertensive effects of blueberry consumption. Groups (n = 8) of male spontaneously hypertensive rats were fed one of four AIN '93G-based diets for 8 weeks: Control (CON); 3% freeze-dried wild blueberry (BB); 1% probiotic bacteria (PRO); or 3% BB + 1% PRO (BB+PRO). Blood pressure was measured at weeks 0, 2, 4, 6, and 8 by the tail-cuff method, and urine was collected at weeks 4 and 8 to determine markers of oxidative stress (F2-isoprostanes), nitric oxide synthesis (nitrites), and polyphenol metabolism (hippuric acid). Data were analyzed using mixed models ANOVA with repeated measures. Diet had a significant main effect on diastolic blood pressure (p = 0.046), with significantly lower measurements in the BB- vs. CON-fed rats (p = 0.035). Systolic blood pressure showed a similar but less pronounced response to diet (p = 0.220), again with the largest difference between the BB and CON groups. Absolute increase in blood pressure between weeks 0 and 8 tended to be smaller in the BB and PRO vs. CON and BB+PRO groups (systolic increase, p = 0.074; diastolic increase, p = 0.185). Diet had a significant main effect on hippuric acid excretion (p<0.0001), with 2- and ~1.5-fold higher levels at weeks 4 and 8, respectively, in the BB and BB+PRO vs. PRO and CON groups. Diet did not have a significant main effect on F2-isoprostane (p = 0.159) or nitrite excretion (p = 0.670). Our findings show that adding probiotics to a blueberry-enriched diet does not enhance and actually may impair the anti-hypertensive effect of blueberry consumption. However, probiotic bacteria are not interfering with blueberry polyphenol metabolism into hippuric acid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antihypertensive Agents / pharmacology*
  • Biological Availability
  • Blood Pressure / drug effects
  • Blueberry Plants / chemistry*
  • Body Weight / drug effects
  • Eating / drug effects
  • Hippurates / metabolism*
  • Hypertension / diet therapy*
  • Hypertension / metabolism
  • Hypertension / microbiology*
  • Male
  • Microbiota / drug effects
  • Nitric Oxide / biosynthesis
  • Oxidative Stress / drug effects
  • Polyphenols / pharmacokinetics
  • Polyphenols / pharmacology
  • Probiotics / pharmacology*
  • Rats
  • Rats, Inbred SHR

Substances

  • Antihypertensive Agents
  • Hippurates
  • Polyphenols
  • Nitric Oxide
  • hippuric acid

Grants and funding

The Wild Blueberry Association of North America (WBANA) provided $5000 USD to support this research. The financial support is not associated with a grant number. Marva Sweeney-Nixon has received funding from WBANA in the past and she was PI on this funding support (http://www.wildblueberries.com/health-research/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.