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Epidemiology
Research
Total volume and composition of fluid intake and mortality in older women: a cohort study
  1. Wai H Lim1,2,
  2. Germaine Wong3,4,
  3. Joshua R Lewis1,3,
  4. Charmaine E Lok5,
  5. Kevan R Polkinghorne6,7,8,
  6. Jonathan Hodgson1,9,
  7. Ee M Lim10,
  8. Richard L Prince1,11
  1. 1Sir Charles Gairdner Hospital Unit, University of Western Australia School of Medicine and Pharmacology, Perth, Western Australia, Australia
  2. 2Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  3. 3Centre for Kidney Research, Children's Hospital at Westmead, Sydney, New South Wales, Australia
  4. 4School of Public Health, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
  5. 5Department of Medicine, University of Toronto; Division of Nephrology, Toronto General Hospital, Toronto, Ontario, Canada
  6. 6Department of Nephrology, Monash Medical Centre, Clayton, Melbourne, Australia
  7. 7Department of Medicine, Monash University, Clayton, Melbourne, Australia
  8. 8Department of Epidemiology and Preventive Medicine, Monash University, Prahan, Melbourne, Australia
  9. 9School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
  10. 10PathWest, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  11. 11Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  1. Correspondence to Dr Wai H Lim; wai.lim{at}health.wa.gov.au

Abstract

Objectives The health benefits of ‘drinking at least 8 glasses of water a day” in healthy individuals are largely unproven. We aimed to examine the relationship between total fluid and the sources of fluid consumption, risk of rapid renal decline, cardiovascular disease (CVD) mortality and all-cause mortality in elderly women.

Design, setting and participants We conducted a longitudinal analysis of a population-based cohort study of 1055 women aged ≥70 years residing in Australia.

Main outcome measures The associations between total daily fluid intake (defined as total volume of beverage excluding alcohol and milk) and the types of fluid (water, black tea, coffee, milk and other fluids) measured as cups per day and rapid renal decline, CVD and all-cause mortality were assessed using adjusted logistic and Cox regression analyses.

Results Over a follow-up period of 10 years, 70 (6.6%) experienced rapid renal decline and 362 (34.4%) died, of which 142 (13.5%) deaths were attributed to CVD. The median (IQR) intake of total fluid was 10.4 (8.5–12.5) cups per day, with water (median (IQR) 4 (2–6) cups per day) and black tea (median (IQR) 3 (1–4) cups per day) being the most frequent type of fluid consumed. Every cup per day higher intake of black tea was associated with adjusted HRs of 0.90 (95% CI 0.81 to 0.99) and 0.92 (95% CI 0.86 to 0.98) for CVD mortality and all-cause mortality, respectively. There were no associations between black tea intake and rapid renal decline, or between the quantity or type of other fluids, including water intake, and any clinical outcomes.

Conclusions Habitual higher intake of black tea may potentially improve long-term health outcomes, independent of treating traditional CVD risk factors, but validation of our study findings is essential.

  • fluid intake
  • EPIDEMIOLOGY
  • elderly
  • mortality
  • tea

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2016-011720

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    Footnotes

    • WHL, GW and JRL contributed equally.

    • Contributors All authors participated in the design of the work, interpretation of the data (WHL, GW and JRL participated in the conception and analysis), drafting of the work, given final approval and are accountable for all aspects of the work. The lead author (WHL) affirms that the manuscript is an honest, accurate and transparent account of the study being reported; and that any discrepancies from the study as planned have been explained.

    • Funding The study was supported by Healthway Health Promotion Foundation of Western Australia, Sir Charles Gairdner Hospital Research Advisory Committee Grant and by project grants 254627, 303169 and 572604 from the National Health and Medical Research Council of Australia. The salary of JRL is supported by a National Health and Medical Research Council of Australia Career Development Fellowship.

    • Competing interests None declared.

    • Ethics approval The Human Ethics Committee of the University of Western Australia approved the study protocol and consent forms (approval number 05/06/004/H50).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Data regarding this cohort (plus other available variables for this cohort) can be requested from http://www.lsaw.com.au/pages/view/about.