Protective effect of tannic acid in mice receiving dietary lead
Mice fed a diet containing both tannic acid and lead acetate showed increased weight gain and greater fecundity when compared with those on a diet containing lead acetate alone. The most significant improvement was provided by adding 2% tannic acid (wt/wt) to ground food containing 3% lead acetate. The affinity of tannic acid for heavy metals is suggested as a reason for this protective effect.
Peaslee, M. H., and F. A. Einhellig. "Protective effect of tannic acid in mice receiving dietary lead." Experientia 33, no. 9 (1977): 1206-1206.