Original Article
European Journal of Clinical Nutrition (2006) 60, 1–8. doi:10.1038/sj.ejcn.1602260; published online 24 August 2005
Influence of tea drinking on manganese intake, manganese status and leucocyte expression of MnSOD and cytosolic aminopeptidase P
Guarantor: JJ Powell.
Contributors: JJP is a nutritional scientist and he devised the overall study with help from KLG (nutritionist). KD is a molecular biologist and he devised and undertook the preparation of RNA/cDNA and the PCR analysis with help from S-JH (PhD student) and JJP. MN is a nutritional epidemiologist and he devised and advised on the FFQ including its administration and analysis, which were undertaken by S-JH with help on the administration from KLG. S-JH and SC (analytical chemist) devised the methodology for and undertook all Mn analyses. S-JH and KLG recruited and venesected the volunteers. S-JH prepared the blood, plasma and white cells. All authors contributed to data analysis, which was coordinated by JJP. All authors contributed to the writing and the editing of the manuscript, which was coordinated by SJ-H and JJP.
S-J Hope1, K Daniel2, K L Gleason3, S Comber1, M Nelson3 and J J Powell3,4
- 1WRc-NSF Ltd, Henley Road, Medmenham, Marlow, Buckinghamshire, UK
- 2Kings College London, Department of Immunology, The Rayne Institute, Denmark Hill, London, UK
- 3Kings College London, Department of Nutrition and Dietetics, 150 Stamford Street, London, UK
- 4MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, UK
Correspondence: Professor JJ Powell, MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK. E-mail: jonathan.powell@mrc-hnr.cam.ac.uk
Received 5 October 2004; Revised 23 May 2005; Accepted 16 June 2005; Published online 24 August 2005.
Abstract
Objective:
Since black tea contains high levels of manganese (Mn), we investigated the relationship between dietary Mn intake, circulating Mn levels and leucocyte expression of two Mn-dependent enzymes in tea drinkers and non-tea drinkers.
Design:
We assessed Mn intakes (food frequency questionnaire), fasting whole blood and plasma Mn levels, and quantitative expression of peripheral blood mononuclear cell Mn-dependent superoxide dismutase (MnSOD) and cytosolic aminopeptidase-P (cAP-P).
Setting and subjects:
In total, 24 tea drinkers (
1 l black tea/day) and 28 non-tea drinkers were recruited from the staff and students of King's College London by circular email.
Results:
Dietary Mn intakes (mean (range)) were significantly lower (P<0.0001) in non tea drinkers (3.2 mg/day (0.5–6.5)) than tea drinkers (5.5 mg/day (2–12) or 10 mg/day (5–20) depending upon the value used for Mn levels of black tea). Whole blood, plasma Mn levels and expression of MnSOD and cAP-P did not differ between the groups. In a continuous analysis, whole blood Mn levels and expression of MnSOD correlated inversely but no other parameters associated with each other.
Conclusions:
Tea drinking is a major source of dietary Mn and intakes commonly exceed proposed adequate intake values of 1.8–2.3 mg Mn/day and, on occasion, exceed upper limits of 10–11 mg/day. Dietary Mn intake has little influence on markers of Mn status or expression of Mn-dependent enzymes. Fasting whole blood Mn levels and leucocyte expression of MnSOD could, together, be further investigated as markers of Mn status.
Sponsporship:
S-JH was supported through the EPSRC PTP scheme. Running costs were from the UK Technical Tea Trade Association.
Keywords:
manganese, intake, status, tea, superoxide dismutase, cytosolic aminopeptidase P
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