Is Indian tea (chai) detrimental to dietary iron absorption?

Indian tea preparation involves addition of milk to brewed black tea. It is a well-known fact that individually both tea polyphenols and milk proteins inhibit iron absorption by forming complexes with dietary iron, rendering it insoluble in the gut. However, when present in combination these dietary components could have an ambiguous effect of either increasing the available iron by binding each other or decreasing iron availability by showing additive inhibitory effect. Our objective was to investigate effect of milk addition to tea on iron bioavailability using in vitro digestion method. Treatments namely, tea only (A), tea+milk (B) and milk only (C), were mixed with FeCl3 to yield solutions that are 5 mM in iron. These solutions were subjected to simulated gastrointestinal digestion and were further estimated for percent dialyzability and solubility of iron using ferrozine as indicator. Results obtained showed that dialyzable iron in the treatment of tea with milk was lowest (19.83 ± 1.71% of total iron in the treatment) compared to treatment of tea only (30.8 ± 2.03%) and milk only (24.72 ± 3.73%). Our results suggest that tea and milk when taken together could have higher deleterious effect on iron availability than taken individually, and this might be a possible factor contributing to the prevailing iron deficiency throughout the country.