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Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial.

Abstract

There is a belief that caffeinated drinks, such as tea, may adversely affect hydration. This was investigated in a randomised controlled trial. Healthy resting males (n 21) were recruited from the general population. Following 24 h of abstention from caffeine, alcohol and vigorous physical activity, including a 10 h overnight fast, all men underwent four separate test days in a counter-balanced order with a 5 d washout in between. The test beverages, provided at regular intervals, were 4 × 240 ml black (i.e. regular) tea and 6 × 240 ml black tea, providing 168 or 252 mg of caffeine. The controls were identical amounts of boiled water. The tea was prepared in a standardised way from tea bags and included 20 ml of semi-skimmed milk. All food taken during the 12 h intervention period was controlled, and subjects remained at rest. No other beverages were offered. Blood was sampled at 0, 1, 2, 4, 8 and 12 h, and a 24 h urine sample was collected. Outcome variables were whole blood cell count, Na, K, bicarbonate, total protein, urea, creatinine and osmolality for blood; and total volume, colour, Na, K, creatinine and osmolality for urine. Although data for all twenty-one participants were included in the analysis (mean age 36 years and mean BMI 25·8 kg/m(2)), nineteen men completed all conditions. Statistical analysis, using a factorial ANOVA approach within PROC MIXED, revealed no significant differences between tea and water for any of the mean blood or urine measurements. It was concluded that black tea, in the amounts studied, offered similar hydrating properties to water.

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  • Publisher Full Text
  • Authors+Show Affiliations

    ,

    Nutrition Communications, Front Lebanon, Cupar, UK. carrie@nutrition-communications.com

    Source

    The British journal of nutrition 106:4 2011 Aug pg 588-95

    MeSH

    Adult
    Caffeine
    Cross-Over Studies
    Dehydration
    Humans
    Kinetics
    Male
    Middle Aged
    Potassium
    Sodium
    Tea
    Water-Electrolyte Balance
    Young Adult

    Pub Type(s)

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

    Language

    eng

    PubMed ID

    21450118

    Citation

    Ruxton, Carrie H., and Valerie A. Hart. "Black Tea Is Not Significantly Different From Water in the Maintenance of Normal Hydration in Human Subjects: Results From a Randomised Controlled Trial." The British Journal of Nutrition, vol. 106, no. 4, 2011, pp. 588-95.
    Ruxton CH, Hart VA. Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial. Br J Nutr. 2011;106(4):588-95.
    Ruxton, C. H., & Hart, V. A. (2011). Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial. The British Journal of Nutrition, 106(4), pp. 588-95. doi:10.1017/S0007114511000456.
    Ruxton CH, Hart VA. Black Tea Is Not Significantly Different From Water in the Maintenance of Normal Hydration in Human Subjects: Results From a Randomised Controlled Trial. Br J Nutr. 2011;106(4):588-95. PubMed PMID: 21450118.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trial. AU - Ruxton,Carrie H, AU - Hart,Valerie A, Y1 - 2011/03/30/ PY - 2011/4/1/entrez PY - 2011/4/1/pubmed PY - 2011/10/1/medline SP - 588 EP - 95 JF - The British journal of nutrition JO - Br. J. Nutr. VL - 106 IS - 4 N2 - There is a belief that caffeinated drinks, such as tea, may adversely affect hydration. This was investigated in a randomised controlled trial. Healthy resting males (n 21) were recruited from the general population. Following 24 h of abstention from caffeine, alcohol and vigorous physical activity, including a 10 h overnight fast, all men underwent four separate test days in a counter-balanced order with a 5 d washout in between. The test beverages, provided at regular intervals, were 4 × 240 ml black (i.e. regular) tea and 6 × 240 ml black tea, providing 168 or 252 mg of caffeine. The controls were identical amounts of boiled water. The tea was prepared in a standardised way from tea bags and included 20 ml of semi-skimmed milk. All food taken during the 12 h intervention period was controlled, and subjects remained at rest. No other beverages were offered. Blood was sampled at 0, 1, 2, 4, 8 and 12 h, and a 24 h urine sample was collected. Outcome variables were whole blood cell count, Na, K, bicarbonate, total protein, urea, creatinine and osmolality for blood; and total volume, colour, Na, K, creatinine and osmolality for urine. Although data for all twenty-one participants were included in the analysis (mean age 36 years and mean BMI 25·8 kg/m(2)), nineteen men completed all conditions. Statistical analysis, using a factorial ANOVA approach within PROC MIXED, revealed no significant differences between tea and water for any of the mean blood or urine measurements. It was concluded that black tea, in the amounts studied, offered similar hydrating properties to water. SN - 1475-2662 UR - https://www.unboundmedicine.com/medline/citation/21450118/abstract/Black_tea_is_not_significantly_different_from_water_in_the_maintenance_of_normal_hydration_in_human_subjects:_results_from_a_randomised_controlled_trial_ L2 - https://www.cambridge.org/core/product/identifier/S0007114511000456/type/journal_article DB - PRIME DP - Unbound Medicine ER -