Previous research has shown that resveratrol can increase cerebral blood flow (CBF) in the absence of improved cognitive performance in healthy, young human subjects during the performance of cognitively demanding tasks. This lack of cognitive effects may be due to low bioavailability and, in turn, reduced bioefficacy of resveratrol in vivo. Piperine can alter polyphenol pharmacokinetics, but previous studies have not investigated whether this affects the efficacy of the target compound. Therefore, the objective of the present study was to ascertain whether co-supplementation of piperine with resveratrol affects the bioavailability and efficacy of resveratrol with regard to cognition and CBF. The present study utilised a randomised, double-blind, placebo-controlled, within-subjects design, where twenty-three adults were given placebo, trans-resveratrol (250 mg) and trans-resveratrol with 20 mg piperine on separate days at least a week apart. After a 40 min rest/absorption period, the participants performed a selection of cognitive tasks and CBF was assessed throughout the period, in the frontal cortex, using near-IR spectroscopy. The presence of resveratrol and its conjugates in the plasma was confirmed by liquid chromatography -MS analysis carried out following the administration of the same doses in a separate cohort (n 6). The results indicated that when co-supplemented, piperine and resveratrol significantly augmented CBF during task performance in comparison with placebo and resveratrol alone. Cognitive function, mood and blood pressure were not affected. The plasma concentrations of resveratrol and its metabolites were not significantly different between the treatments, which indicates that co-supplementation of piperine with resveratrol enhances the bioefficacy of resveratrol with regard to CBF effects, but not cognitive performance, and does this without altering bioavailability.

Plant roots and animal guts have evolved specialized cells layers to control mineral nutrient homeostasis that must tolerate the resident microbiota while keeping homeostatic integrity. Whether and how the root diffusion barriers in the endodermis, critical for the mineral nutrient balance of plants, coordinates with the microbiota, is unknown. We demonstrate that genes controlling endodermal function in the model plant Arabidopsis thaliana contribute to the plant microbiome assembly. We characterize a regulatory mechanism of endodermal differentiation driven by the microbiota with profound effects on nutrient homeostasis. Furthermore, we demonstrate that this mechanism is linked to the microbiota’s capacity to repress responses to the phytohormone abscisic acid in the root. Our findings establish the endodermis as a regulatory hub coordinating microbiota assembly and homeostatic mechanisms.

Single doses of resveratrol have previously been shown to increase cerebral blood flow (CBF) with no clear effect on cognitive function or mood in healthy adults. Chronic resveratrol consumption may increase the poor bioavailability of resveratrol or otherwise potentiate its psychological effects. In this randomised, double-blind, placebo-controlled, parallel-groups study, a total of sixty adults aged between 18 and 30 years received either placebo or resveratrol for 28 d. On the 1st and 28th day of treatment, the performance of cognitively demanding tasks (serial subtractions, rapid visual information processing and 3-Back) (n 41 complete data sets) was assessed, alongside blood pressure (n 26) and acute (near-IR spectroscopy (NIRS)) and chronic (transcranial Doppler) measures of CBF (n 46). Subjective mood, sleep quality and health questionnaires were completed at weekly intervals (n 53/54). The results showed that the cognitive effects of resveratrol on day 1 were restricted to more accurate but slower serial subtraction task performance. The only cognitive finding on day 28 was a beneficial effect of resveratrol on the accuracy of the 3-Back task before treatment consumption. Subjective ratings of 'fatigue' were significantly lower across the entire 28 d in the resveratrol condition. Resveratrol also resulted in modulation of CBF parameters on day 1, as assessed by NIRS, and significantly increased diastolic blood pressure on day 28. Levels of resveratrol metabolites were significantly higher both before and after the day's treatment on day 28, in comparison with day 1. These results confirm the acute CBF effects of resveratrol and the lack of interpretable cognitive effects.

We have positively identified metabolites and conjugates, some novel, in the urine of healthy volunteers after intake of multiple phenolics from a mixed puree from berry fruits, with each being excreted at specific and signature times. Some of these compounds could potentially be used as biomarkers of fruit intake. The possible biological activities of these colonic metabolites require further assessment.