Final answer:
Tea most adversely affects the absorption of iron due to phytic and oxalic acids which form insoluble compounds with iron. Orange juice enhances absorption by converting iron into a more soluble state.
Step-by-step explanation:
The menu item that would most adversely affect the absorption of iron is tea. Tea contains substances like phytic acid and oxalic acid which form insoluble compounds with iron, thereby decreasing its absorption. On the contrary, items such as orange juice could potentially enhance iron absorption due to the presence of ascorbic acid which converts ferric iron into the more soluble ferrous state. Milk may also impact iron absorption due to its calcium content which, in excess, can interfere with iron absorption; however, the effect is generally less pronounced than that of the compounds found in tea.
Club soda, being essentially water with added carbonation, is least likely to affect iron absorption. It's important to understand that iron absorption mainly occurs in the duodenum and the proximal jejunum, and the body's need for iron, as well as its current levels of saturation, plays a significant role in how much iron is absorbed.