Which substance inhibits non-heme iron absorption?

• A. Phytates
• B. Vitamin C
• C. Heme iron
• D. Vitamin A

Answer: (A)

Non-heme iron absorption is especially vulnerable to dietary inhibitors. Phytates bind iron in the intestinal lumen, forming insoluble iron-phytate complexes that stay poorly soluble at gut pH. This prevents iron from being solubilized and taken up by enterocytes, reducing absorption of non-heme iron from plant-based sources. By contrast, vitamin C enhances non-heme iron absorption by reducing ferric to ferrous iron and creating soluble complexes, so it doesn’t inhibit. Heme iron, from animal foods, is absorbed by a different mechanism and is less affected by phytates. Vitamin A doesn’t act as a direct inhibitor in this context.