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

Eur J Clin Nutr. 2006 Jan;60(1):1-8. doi: 10.1038/sj.ejcn.1602260.

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 (> 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aminopeptidases / metabolism*
  • Beverages
  • Case-Control Studies
  • Female
  • Humans
  • Male
  • Manganese / administration & dosage*
  • Manganese / blood
  • Manganese / metabolism*
  • Middle Aged
  • Nutrition Policy
  • Nutritional Status
  • Superoxide Dismutase / metabolism*
  • Surveys and Questionnaires
  • Tea / chemistry*
  • United Kingdom

Substances

  • Tea
  • Manganese
  • Superoxide Dismutase
  • Aminopeptidases
  • X-Pro aminopeptidase