I drink black tea but my hair analysis showed low Mn.
Drinking black tea does seem to increase Mn intake, but not markers of Mn status or expression of Mn-dependent enzymes according to this 2005 study in a sample population of students and staff at Kings College London.
Influence of tea drinking on manganese intake, manganese status and leucocyte expression of MnSOD and cytosolic aminopeptidase P
https://www.nature.com/articles/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 (>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.