Influence of tea drinking on manganese intake, manganese status and leucocyte expression of MnSOD and cytosolic aminopeptidase P.
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.


METHODS
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).


METHODS
In total, 24 tea drinkers (> or = 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.
Hope
S- J
S
WRc-NSF Ltd, Henley Road, Medmenham, Marlow, Buckinghamshire, UK.
Daniel
K
K
Gleason
K L
KL
Comber
S
S
Nelson
M
M
Powell
J J
JJ
D000328:Adult; D000626:Aminopeptidases / Q000378:metabolism*; D001628:Beverages; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008345:Manganese / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism*; D008875:Middle Aged; D018673:Nutrition Policy; D009752:Nutritional Status; D013482:Superoxide Dismutase / Q000378:metabolism*; D011795:Surveys and Questionnaires; D013662:Tea / Q000737:chemistry*; D006113:United Kingdom
D013662:Tea; D008345:Manganese; D013482:Superoxide Dismutase; D000626:Aminopeptidases; C022750:X-Pro aminopeptidase