Acute black tea consumption improves cutaneous vascular function in healthy middle-aged humans.

BACKGROUND & AIMS: Dietary flavonoids, such as those present in black tea, are associated with reduced risk of cardiovascular disease (CVD), possibly through improving nitric oxide (NO) mediated vascular function. The aim of this study was to examine the effect of acute black tea ingestion on cutaneous microvascular function. METHODS: Twenty healthy participants (58 ± 5 y, 9 men) attended two experimental trials (tea, placebo), 7-days apart in a randomised, controlled, double-blind, cross-over design. Participants ingested a single dose of 200 ml black tea or placebo, followed by assessment of forearm cutaneous perfusion using laser-Doppler flowmetry (LDF) using three distinct heating protocols, enabling us to distinguish between axon- and endothelium-dependent vasodilation: 1. rapid 42°C, 2. rapid 39°C and 3. gradual 42°C. On the contralateral arm, full-field laser perfusion imaging (FLPI) was used to assess forearm perfusion during gradual 42°C. Data were presented as cutaneous vascular conductance (CVC; flux/mean arterial pressure, MAP) and CVC expressed as a percentage of maximal CVC (%CVCmax). RESULTS: Rapid local heating to 39°C or 42°C demonstrated no effect of tea for flux, CVC or %CVCmax (all P > 0.05). Gradual local heating to 42 °C, however, produced a higher skin blood flow following black tea ingestion for absolute CVC (P = 0.04) when measured by LDF, and higher absolute flux (P < 0.001) and CVC (P < 0.001) measured with FLPI. No effect of tea was found for %CVCmax when assessed by either LDF or FLPI. CONCLUSIONS: Acute tea ingestion enhanced cutaneous vascular responses to gradual local heating to 42 °C in healthy, middle-aged participants, possibly through a mechanism related to activation of endothelium-derived chemical mediators, such as NO. These improvements may contribute to the cardiovascular health benefits of regular tea ingestion.

Polyphenols and Microvascular Function in Humans: A Systematic Review.

BACKGROUND: Polyphenol-rich dietary sources are acknowledged to have potential cardiovascular health benefits, particularly in reducing cardiovascular disease risk. METHODS: This systematic review sought to determine the effect of polyphenol-rich foods and beverages upon microvascular function, which is of considerable importance in its contribution towards the pathophysiology of microvascular-related complications but also in the future development of (macro-vessel) cardiovascular disease. RESULTS: Overall, consumption of polyphenol-rich foods and beverages demonstrate improved microvascular function, although this is dependent upon the polyphenol source, the dose of the product, the duration of consumption and the population group studied. Most subgroups reviewed suggest an overall beneficial effect on microvascular function, particularly grape-derived products, cocoa, tea, pine bark and Rutaceae aurantiae. Other groups remain equivocal and require further study due to the limited research performed to date. CONCLUSION: Polyphenols are abundant in the human diet and this systematic review demonstrates that they are an inexpensive, non-pharmacological approach for improving cardiovascular health in currently healthy individuals and in populations with microvascular dysfunction.

Forearm Skin Blood Flow After Kinesiology Taping in Healthy Soccer Players: An Exploratory Investigation.

CONTEXT: Kinesiology tape (KT) has become popular among athletes for both injury prevention and rehabilitation due to its reported therapeutic effects, including facilitation of lymphatic flow and enhanced peripheral blood flow. However, evidence to support such claims is insufficient. OBJECTIVE: To determine whether KT improves skin blood flow (SkBF) responses in young, elite soccer players. DESIGN: Randomized crossover study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirteen healthy, elite, adolescent male soccer players (age = 14.7 ± 0.6 years). INTERVENTION(S): Participants completed 2 experimental trials; during trial 1, the volar aspect of the dominant forearm was taped. Forearm SkBF was measured within the taped area and 3 cm lateral to the taped area. During trial 2, no tape was applied to either site. Both trials were performed within 7 days. MAIN OUTCOME MEASURE(S): Baseline and maximal thermally (42°C) stimulated SkBF responses were assessed using laser Doppler flowmetry. Continuously measured SkBF and derived mean arterial pressure obtained at 5-minute intervals were used to calculate cutaneous vascular conductance (CVC), the primary outcome measure. RESULTS: No differences were observed for baseline SkBF or CVC between trials or measurement sites. After local heating, no differences were evident for SkBF or CVC between trials or measurement sites. CONCLUSIONS: Our findings suggest that, in healthy, trained adolescent males, KT was not associated with increased forearm SkBF.