• 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.

      Ahmad Fuzi, Salma F.; Koller, Dagmar; Brugrabber, Sylvaine; Pereira, Dora I. A.; Dainty, Jack R.; Mushtaq, Sohail; University of Chester; Elsie Widdowson Laboratory, Cambridge; University of East Anglia; University Putra Malaysia (American Society for Nutrition, 2017-10-18)
      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 6 SD age: 24.8 6 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% 6 8.5% (TM-1), 3.6% 6 4.2% (TM-2), and 5.7% 6 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 w50% 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.
    • Dietary vitamin D supplementation improves haematological status following consumption of an iron-fortified cereal: an 8-week randomised controlled trial

      Mushtaq, Sohail; Ahmad Fuzi, Salma F.; University of Chester
      Vitamin D, a secosteroid, has recently been implicated in the stimulation of erythroid precursors and ultimately the rate of erythropoiesis. However, there are a paucity of randomised controlled trials (RCT), investigating the effect of vitamin D supplementation iron status, especially in populations at risk of iron deficiency. An eight-week, double-blind RCT was carried out in 50 female (mean age (± SD): 27 ± 9 years), iron-deficient (plasma ferritin concentration < 20 μg/L) participants, randomised to consume an iron-fortified cereal containing 9 mg of iron, with either a vitamin D supplement (1,500 international units (IU)/day, 38 μg/day) or placebo. The effect of dietary vitamin D supplementation on haematological indicators was investigated. Blood samples were collected at baseline, 4-weeks and 8-week timepoints for measurement of iron and vitamin D status biomarkers. The effect of intervention was analysed with a mixed-model repeated measures ANOVA using IBM SPSS statistical software (Version 21, IBM Corporation, New York, USA). Significant increases were observed in two haematological parameters: haemoglobin concentration and haematocrit level from baseline to post-intervention in the vitamin D group, but not in the placebo group. The increase from baseline to post-intervention in haemoglobin concentration in the vitamin D group (135 ± 11 to 138 ± 10 g/L) was significantly higher than in the placebo group (131 ± 15 to 128 ± 13 g/L) (P ≤ 0.05). The increase in haematocrit level from baseline to post-intervention was also significantly higher in the vitamin D group (42.0 ± 3.0 to 43.8 49 ± 3.4%) compared to the placebo group (41.2 ± 4.3 to 40.7 ± 3.6%) (P ≤ 0.05). Despite non-significant changes in plasma ferritin concentration, this study demonstrates that dietary supplementation with 1,500IU vitamin D, consumed daily with an iron-fortified cereal led to improvement in haemoglobin concentration and haematocrit levels in women with low iron stores. Further long-term studies are required, however, these findings suggest a potential role for improvement of vitamin D status as an adjunct therapy for recovery of iron status in iron-deficient populations.
    • The effect of dietary components on non-haem iron absorption in healthy and iron-deficient women

      Mushtaq, Sohail; Ahmad Fuzi, Salma F. (University of Chester, 2017-02)
      Two clinical trials investigating the effect of modulating two dietary components, tea containing polyphenols and vitamin D aimed at improving non-haem iron absorption and iron status recovery, were carried out in a cohort of healthy and iron deficient UK women, respectively. Tea has been shown to be a potent inhibitor of non-haem iron absorption but it remains unclear whether the timing of tea consumption relative to a meal influences iron bioavailability, with limited published evidence, especially in human trials. The aim of the first study was to investigate the effect of tea consumption on non-haem iron absorption and to assess the effect of time interval of tea consumption on non-haem iron absorption relative to an iron-containing meal, in a cohort of healthy female participants using a stable iron isotope (57Fe).