A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: a controlled trial in a cohort of healthy UK women using a stable iron isotope [Vitamins, minerals, and phytochemicals]

  1. Salma F Ahmad Fuzi1,2,
  2. Dagmar Koller3,
  3. Sylvaine Bruggraber3,
  4. Dora IA Pereira3,
  5. Jack R Dainty4, and
  6. Sohail Mushtaq1
  1. 1Faculty of Medicine, Dentistry, and Life Sciences, University of Chester, Chester, United Kingdom;
  2. 2Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Selangor, Malaysia;
  3. 3Medical Research Council, Elsie Widdowson Laboratory, Cambridge, United Kingdom; and
  4. 4Norwich Medical School, University of East Anglia, Norwich, United Kingdom
  1. Address correspondence to SM (e-mail: s.mushtaq{at}chester.ac.uk).
  • Supported by the University of Chester; the UK Medical Research Council (grant U105960399) provided support with the iron
    isotopic analyses.

  • Supplemental Tables 1 and 2 are available from the “Online Supporting Material” link in the online posting of the article
    and from the same link in the online table of contents at http://ajcn.nutrition.org.

  • Present address for DK: Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom.

  • Present address for SB: Department of Paediatrics, University of Cambridge, Cambridge, United Kingdom.

  • Present address for DIAP: Department of Pathology, University of Cambridge, Cambridge, United Kingdom.

Abstract

Background: Tea has been shown to be a potent inhibitor of nonheme iron absorption, but it remains unclear whether the timing of tea
consumption relative to a meal influences iron bioavailability.

Objective: The aim of the study was to investigate the effect of a 1-h time interval of tea consumption on nonheme iron absorption in
an iron-containing meal in a cohort of iron-replete, nonanemic female subjects with the use of a stable isotope (57Fe).

Design: Twelve women (mean ± SD age: 24.8 ± 6.9 y) were administered a standardized porridge meal extrinsically labeled with 4 mg
57Fe as FeSO4 on 3 separate occasions, with a 14-d time interval between each test meal (TM). The TM was administered with water (TM-1),
with tea administered simultaneously (TM-2), and with tea administered 1 h postmeal (TM-3). Fasted venous blood samples were
collected for iron isotopic analysis and measurement of iron status biomarkers. Fractional iron absorption was estimated by
the erythrocyte iron incorporation method.

Results: Iron absorption was 5.7% ± 8.5% (TM-1), 3.6% ± 4.2% (TM-2), and 5.7% ± 5.4% (TM-3). Mean fractional iron absorption was found
to be significantly higher (2.2%) when tea was administered 1 h postmeal (TM-3) than when tea was administered simultaneously
with the meal (TM-2) (P = 0.046). An ∼50% reduction in the inhibitory effect of tea (relative to water) was observed, from 37.2% (TM-2) to 18.1%
(TM-3).

Conclusions: This study shows that tea consumed simultaneously with an iron-containing porridge meal leads to decreased nonheme iron absorption
and that a 1-h time interval between a meal and tea consumption attenuates the inhibitory effect, resulting in increased nonheme
iron absorption. These findings are not only important in relation to the management of iron deficiency but should also inform
dietary advice, especially that given to those at risk of deficiency. This trial was registered at clinicaltrials.gov as NCT02365103.

Keywords:

Footnotes

  • Abbreviations used: CRP, C-reactive protein; ICP-MS/MS, inductively coupled plasma–tandem mass spectrometry; TM, test meal.

  • Received May 25, 2017.
  • Accepted September 13, 2017.

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