Chemical Forms of Iron, Calcium, Magnesium, Zinc, and Copper from Rats Diets Containing Tea

Chemical forms of iron, calcium, magnesium, zinc and copper were measured in rat diets containing 0-3.5% instant black tea. As instant tea in diets increased, more iron was soluble and ionic. Diets containing tea had more complexed iron than without. Calcium had low solubility (10-12%) while almost all magnesium (92-98%) was soluble in all diets. Solubility of zinc and copper increased as the level of tea in diets increased. Chemical availability of iron, calcium, magnesium and zinc was measured in a rat diet without tea (control), containing 2.31% black tea solids and containing 2.31% green tea solids. The control had more soluble (56%), ionic (37%) and complexed (19%) iron than green tea (18%, 2.3%, 16%, respectively) or black tea (8.7%, 4.8%, 3.9%, respectively) diets. Diets did not differ in calcium or magnesium solubility. Zinc was more soluble in both tea diets than the control. Some mineral profiles of the rat diets could be predicted by mineral profiles of teas alone. Changes in mineral profiles were induced by mixing tea with diet components or by freeze drying tea. Chemical availability of minerals in rat diets predicted some but not all results from a rat bioavailability assay.