Which of the following substances can inhibit iron absorption?

Calcium is known to inhibit iron absorption in the body. When calcium is present in the digestive system, it can compete with iron for absorption in the intestine. This is particularly relevant when calcium and iron are consumed together, as the presence of calcium may hinder the bioavailability of iron, making it less accessible for absorption into the bloodstream. Studies have shown that high doses of calcium can significantly decrease the absorption of non-heme iron, which is the type found in plant-based foods and supplements.

In contrast, Vitamin C is known to enhance iron absorption, particularly non-heme iron, by converting it into a more soluble form that is easier for the intestines to absorb. Folic acid and potassium do not have a significant direct impact on iron absorption. Folic acid plays a role in red blood cell formation and overall health but does not prevent iron absorption. Potassium is not linked to iron absorption mechanisms in the body.