Can black tea influence plasma total homocysteine concentrations

Background: Polyphenols can act as acceptors of methyl groups during the metabolism of methionine to homocysteine. This may result in elevations in plasma total homocysteine (tHcy) concentrations after ingestion of polyphenol-rich beverages such as tea. Objectives: Our major objective was to determine whether regular, moderate-to-high intakes of black tea alter tHcy concentrations. We also assessed the relation between the degree of O-methylation of tea-derived polyphenols and the change in tHcy with regular ingestion of tea.Design: Twenty-two subjects completed a randomized, controlled crossover study. Subjects consumed 1250 mL black tea/d (5 cups each containing 2 g tea leaves in 250 mL boiled water) and 1250 mL hot water/d for 4 wk each. Fasting tHcy concentrations and 24-h urinary excretion of 4-O-methylgallic acid (40MGA, the major O-methylated metabolite of gallic acid) were measured at the end of each period. 40MGA was used as a marker of overall O-methylation of tea-derived polyphenols.Results: Black tea did not significantly alter mean ( SEM) tHcy concentrations (9.9 +/- 0.5 and 10.0 +/- 0.5 mumol/L for the hot water and black tea periods, respectively). However, the increased excretion of 40MGA as a consequence of black tea consumption was positively associated with the change in tHcy from the hot water period to the black tea period (r = 0.55, P = 0.008). Subjects in the bottom quartile of increase in 40MGA excretion had a significant decrease in tHcy (-0.28 0.10 mumol/L; P = 0.046), and those in the top quartile had a significant increase in tHcy (0.78 +/- 0.16 mumol/L; P = 0.005).Conclusions: Overall, regular ingestion of black tea did not alter mean tHcy concentrations. However, individual differences in O-methylation of polyphenolic compounds may influence the ultimate effects of black tea on tHcy.