Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers

doi:10.1017/S1368980010000170

Paper

Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers

Published Feb 10, 2010 · I. Persson, Karin Persson, S. Hägg

Public Health Nutrition

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56

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Abstract

Abstract Objective Tea has been reported to reduce cardiovascular mortality, but the underlying mechanisms are largely unknown. The aim of the current project was to investigate the effect of green tea (Japanese Sencha), black tea (Indian Assam B.O.P.) and Rooibos tea (South Africa) on angiotensin-converting enzyme (ACE) and nitric oxide (NO). Design Seventeen healthy volunteers received a single oral dose of 400 ml green tea, black tea or Rooibos tea in a randomized, three-phase, crossover study. ACE activity and NO concentration were measured (at 0, 30, 60 and 180 min) in all phases. ACE activity was analysed by means of a commercial radioenzymatic assay. Nitrite was analysed as a marker of NO concentration. In addition, ACE genotype was determined using a PCR method. Results Oral intake of a single dose of Rooibos tea significantly inhibited ACE activity after 30 min (P < 0·01) and after 60 min (P < 0·05). A significant inhibition of ACE activity was seen with green tea for the ACE II genotype 30 min after intake of the tea (P < 0·05) and for the ACE ID genotype 60 min after intake (P < 0·05). A significant inhibition of ACE activity was also seen with Rooibos tea for the ACE II genotype 60 min after intake (P < 0·05). No significant effect on NO concentration was seen. Conclusions These results suggest that green tea and Rooibos tea may have cardiovascular effects through inhibition of ACE activity.

RCT

Study Snapshot

Green tea and Rooibos tea may have cardiovascular effects through inhibition of ACE activity, while black tea and nitric oxide show no significant effect on ACE activity.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Effects of green tea, black tea and Rooibos tea on angiotensin-converting enzyme and nitric oxide in healthy volunteers

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References

Black tea consumption dose-dependently improves flow-mediated dilation in healthy males

Black tea consumption dose-dependently improves flow-mediated dilation and decreases peripheral arterial stiffness in healthy males, suggesting potential protective cardiovascular effects for all tea drinkers.

Flavonoids, flavonoid-rich foods, and cardiovascular risk: a meta-analysis of randomized controlled trials.

Flavonoids from soy and cocoa have been shown to reduce blood pressure and cholesterol, while black tea and green tea have shown mixed effects on blood pressure and LDL cholesterol.

Health effects of quercetin: from antioxidant to nutraceutical.

Quercetin, found in foods and supplements, may have beneficial health effects, including protection against diseases and aging, due to its ability to scavenge reactive species like peroxynitrite and hydroxyl radicals.

Inhibition of cardiovascular cell proliferation by angiotensin receptor blockers: are all molecules the same?

Telmisartan effectively inhibits the proliferation of vascular smooth muscle cells and cardiac fibroblasts, suggesting its antiproliferative effects involve more than just angiotensin II receptor blockade or PPAR activation.

Anti-oxidative and inhibitory activities on nitric oxide (NO) and prostaglandin E2 (COX-2) production of flavonoids from seeds of Prunus tomentosa Thunberg

Six flavonoids from Prunus tomentosa seeds exhibit potent anti-oxidative activity and inhibitory effects on nitric oxide and prostaglandin E2 production.

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