Ascorbic acid–ferrous iron complex

The Ascorbic acid–Fe2+ luminal complex, commonly known as ferrous ascorbate, is a chemical chelate formed in the gastrointestinal tract between vitamin C and ferrous iron (NIH, 2020). Its primary biological role is to enhance the bioavailability of non-heme iron by maintaining it in a soluble, reduced state within the intestinal lumen (The Blood Project, 2025). In the acidic environment of the stomach, ascorbic acid reduces dietary ferric iron (Fe3+) to ferrous iron (Fe2+) and forms a stable complex that prevents iron from precipitating as insoluble hydroxides or phosphates in the more alkaline duodenum (MDPI, 2020). This complex facilitates the transport of iron across the apical membrane of enterocytes via the divalent metal transporter 1 (DMT1). Beyond its role in absorption, the interaction between iron and ascorbate can participate in the Fenton reaction, leading to the generation of reactive oxygen species (ROS) which may cause localized oxidative stress or gastric irritation (NIH, 2020). Clinically, this complex is a key component in oral iron supplements designed to optimize absorption and minimize the inhibitory effects of dietary factors like phytates and polyphenols.

Other names

Ferrous ascorbateVitamin C-iron complexAscorbate-iron complexLuminal iron-ascorbate chelateFe(II)-ascorbate complex

The complex enhances iron bioavailability by reducing ferric iron (Fe3+) to the ferrous state (Fe2+) and forming a soluble chelate that prevents the formation of insoluble iron precipitates in the alkaline environment of the duodenum, thereby facilitating uptake through the divalent metal transporter 1 (DMT1).