Abstract
Iron deficiency and anaemia affect two billion people globally. Iron fortification can help to treat anaemia, but most current fortificants are limited by low absorption and/or poor sensory properties. Here we introduce oat protein nanofibrils (OatNF) carrying ultrasmall iron nanoparticles that are engineered to carry iron in ferrous or ferric form. In a prospective cross-over stable-isotope absorption trial in young iron-deficient women (n = 52), OatNF reduced with sodium ascorbate carried mainly ferrous iron and showed high fractional absorption with water and with polyphenol-rich food, showing 1.76- and 1.65-fold higher absorption, respectively, compared with ferrous sulfate. When sodium hydroxide was used as the reducing agent, OatNF carried mainly ferric iron, which was also well absorbed and featured good sensory properties in reactive food matrices. OatNF hybrids offer a plant-based strategy for delivering highly bioavailable iron for food fortification.