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

Abstract

OBJECTIVES

Flavonoids may protect against cardiovascular disease. Tea is a major source of dietary flavonoids. Studies indicate black tea improves endothelial function but data on arterial haemodynamics, blood pressure (BP) and insulin resistance are equivocal. Inconsistency may be due to flaws in study design or flavonoid doses tested. Further, no study has evaluated the dose-response curve. Our study aimed to test the effects of various doses of black tea on vascular function, BP and insulin resistance.

METHODS

According to a randomized, double-blind, controlled, cross-over design, 19 healthy men were assigned to receive either five treatments with a twice daily intake of black tea (0, 100, 200, 400 and 800 mg tea flavonoids/day) in five periods lasting 1 week each.

RESULTS

Black tea dose dependently increased flow-mediated dilation (FMD) from 7.8% (control) to 9.0, 9.1, 9.6 and 10.3% after the different flavonoid doses, respectively (P = 0.0001). Already 100 mg/day (less than 1 cup of tea) increased FMD compared with control (P = 0.0113). FMD improvement after 800 mg/day was significant compared with control (P < 0.0001) but also to 100 mg/day (P = 0.0121) and 200 mg/day (P = 0.0275). Black tea intake decreased office systolic (-2.6 mmHg, P = 0.0007) and diastolic (-2.2 mmHg, P = 0.006) BP as well as stiffness index (P = 0.0159) without changes in other parameters studied.

CONCLUSION

Our study is the first showing black tea ingestion dose dependently improved FMD and decreased peripheral arterial stiffness in healthy volunteers. Our data suggest that worldwide all tea drinkers could benefit from protective cardiovascular effects exerted by tea.

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  • Authors+Show Affiliations

    ,

    Department of Internal Medicine and Public Health, University of L'Aquila, L'Aquila, Italy. davide.grassi@cc.univaq.it

    , , , ,

    Source

    Journal of hypertension 27:4 2009 Apr pg 774-81

    MeSH

    Adolescent
    Adult
    Aged
    Arteries
    Blood Pressure
    Blood Pressure Monitoring, Ambulatory
    C-Reactive Protein
    Cross-Over Studies
    Dose-Response Relationship, Drug
    Double-Blind Method
    Endothelium, Vascular
    Flavonoids
    Humans
    Insulin Resistance
    Male
    Middle Aged
    Nitric Oxide
    Tea
    Vasodilation

    Pub Type(s)

    Journal Article
    Randomized Controlled Trial
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    19516176

    Citation

    Grassi, Davide, et al. "Black Tea Consumption Dose-dependently Improves Flow-mediated Dilation in Healthy Males." Journal of Hypertension, vol. 27, no. 4, 2009, pp. 774-81.
    Grassi D, Mulder TP, Draijer R, et al. Black tea consumption dose-dependently improves flow-mediated dilation in healthy males. J Hypertens. 2009;27(4):774-81.
    Grassi, D., Mulder, T. P., Draijer, R., Desideri, G., Molhuizen, H. O., & Ferri, C. (2009). Black tea consumption dose-dependently improves flow-mediated dilation in healthy males. Journal of Hypertension, 27(4), pp. 774-81. doi:10.1097/HJH.0b013e328326066c.
    Grassi D, et al. Black Tea Consumption Dose-dependently Improves Flow-mediated Dilation in Healthy Males. J Hypertens. 2009;27(4):774-81. PubMed PMID: 19516176.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Black tea consumption dose-dependently improves flow-mediated dilation in healthy males. AU - Grassi,Davide, AU - Mulder,Theo Pj, AU - Draijer,Richard, AU - Desideri,Giovambattista, AU - Molhuizen,Henri Of, AU - Ferri,Claudio, PY - 2009/6/12/entrez PY - 2009/6/12/pubmed PY - 2009/8/27/medline SP - 774 EP - 81 JF - Journal of hypertension JO - J. Hypertens. VL - 27 IS - 4 N2 - OBJECTIVES: Flavonoids may protect against cardiovascular disease. Tea is a major source of dietary flavonoids. Studies indicate black tea improves endothelial function but data on arterial haemodynamics, blood pressure (BP) and insulin resistance are equivocal. Inconsistency may be due to flaws in study design or flavonoid doses tested. Further, no study has evaluated the dose-response curve. Our study aimed to test the effects of various doses of black tea on vascular function, BP and insulin resistance. METHODS: According to a randomized, double-blind, controlled, cross-over design, 19 healthy men were assigned to receive either five treatments with a twice daily intake of black tea (0, 100, 200, 400 and 800 mg tea flavonoids/day) in five periods lasting 1 week each. RESULTS: Black tea dose dependently increased flow-mediated dilation (FMD) from 7.8% (control) to 9.0, 9.1, 9.6 and 10.3% after the different flavonoid doses, respectively (P = 0.0001). Already 100 mg/day (less than 1 cup of tea) increased FMD compared with control (P = 0.0113). FMD improvement after 800 mg/day was significant compared with control (P < 0.0001) but also to 100 mg/day (P = 0.0121) and 200 mg/day (P = 0.0275). Black tea intake decreased office systolic (-2.6 mmHg, P = 0.0007) and diastolic (-2.2 mmHg, P = 0.006) BP as well as stiffness index (P = 0.0159) without changes in other parameters studied. CONCLUSION: Our study is the first showing black tea ingestion dose dependently improved FMD and decreased peripheral arterial stiffness in healthy volunteers. Our data suggest that worldwide all tea drinkers could benefit from protective cardiovascular effects exerted by tea. SN - 1473-5598 UR - https://www.unboundmedicine.com/medline/citation/19516176/Black_tea_consumption_dose_dependently_improves_flow_mediated_dilation_in_healthy_males_ L2 - http://Insights.ovid.com/pubmed?pmid=19516176 DB - PRIME DP - Unbound Medicine ER -