Adding lemon juice to spinach is a smart nutritional pairing because vitamin C significantly improves the absorption of plant-based iron.

Spinach contains non-heme iron, the form of iron found in plants. Non-heme iron is more sensitive to inhibitors like oxalates and phytates, which can reduce how much iron your body absorbs. Lemon juice is rich in vitamin C, and vitamin C chemically converts non-heme iron into a form that is more easily absorbed in the small intestine. Studies show that vitamin C can substantially increase non-heme iron absorption when consumed in the same meal.