I would be most grateful if you would tell me where to look.
Tea is rich in tannin, which very efficiently complexes iron ions in solution.
The iron-tannate complex can't be assimilated by the body. There are several ways to determine iron in tea. References P. B. Disler, S. R. Lynch, R. W. Charlton, et al. P. B. Disler, S. R. Lynch, J. D. Torrance, et al. Sign up for a free monthly newsletter describing updates, new features, and changes on this site.