Plant-based oat protein hybrid doubles iron absorption in women

By Dr. Liji Thomas, MDReviewed by Lauren HardakerNov 12 2025

A new study from ETH Zurich reveals that tiny iron nanoparticles bound to oat protein nanofibrils nearly double absorption rates in women, offering a clean, plant-based solution to one of the world’s most widespread nutritional deficiencies.

Study: Oat protein nanofibril-iron hybrids as a stable, high-absorption iron delivery platform for human nutrition. Image credit: BooDogz/Shutterstock.com

*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Iron deficiency anemia (IDA) is a global public health concern. While iron fortification and supplements are widely used to increase iron intake, they often suffer from poor absorption and undesirable changes in the taste, smell, or appearance of foods. A recent study published as a preprint on the medRxiv server discusses the synthesis and performance of a novel hybrid form of iron that could transform the field of iron fortification and mitigate the global problem of IDA.

Global impact of iron deficiency

IDA affects a large portion of the nearly two billion people worldwide living with anemia, including 30% of the world’s women. It accounts for 422 years lived with disability per 1,00,000 population, reinforcing the demand for iron fortification of foods.

Young women are recommended to take 18 mg of iron daily through supplementation or iron fortification, as it is unlikely to be supplied through the ordinary diet. Ferrous sulfate is the gold standard for this use, being highly bioavailable and inexpensive.

However, it adversely affects the smell, taste, and appearance of most fortified foods. In many plant-based foods, compounds such as polyphenols and phytic acid hinder the body’s ability to absorb iron, although this effect is reduced with alternatives like sodium iron EDTA. Excess unabsorbed iron in the gut can also lead to inflammation and disrupt the gut microbiome's balance.

The challenge in formulating iron supplements is to obtain highly bioavailable ferrous iron compounds while retaining the appearance, taste, and smell of the food they are contained in intact. The current experiment sought to overcome these barriers using oat protein nanofibrils (OatNF) loaded with ultrasmall iron nanoparticles.

The resulting hybrids were tested in a small cohort of iron-deficient Thai women to assess their bioavailability and absorption, both in the presence of water and in the context of polyphenol-rich foods.

How OatNF binds iron

The OatNF bound, reduced, and stabilized iron strongly. OatNF efficiently binds nanosized iron particles in both ferric and ferrous forms, likely through supramolecular interactions. It also offers strong antioxidant and stabilizing effects, thanks to its abundance of reducing amino acids and other compounds, which help maintain colloidal iron in a stable state.

The synthesis process was tailored to obtain the ferrous or ferric form, as required. For instance, reducing with sodium ascorbate stabilizes iron in ferrous form at the sub-nanoscale on the surface of the OatNF. When synthesized with sodium hydroxide as the reducing agent, ferric iron was the primary deposited form.

About 46% of ferrous iron was absorbed in iron-deficient women from this hybrid molecule when administered with water. Even when consumed with polyphenol-rich foods, about 13% was absorbed. This represents a 76% and 66% increase in absorption compared to ferrous sulfate, respectively.  

The increased iron absorption with the use of sodium ascorbate is probably due to the efficient and stable reduction of iron to stable ferrous form on the surface of this hybrid molecule, coupled with a relative enrichment of glutamine.

The use of sodium hydroxide resulted in a high ferric iron content, but surprisingly high bioavailability. This amounted to 80% and 75% of ferrous sulfate bioavailability in the presence of water and polyphenol-rich food, respectively.

In both cases, the use of the OatNF-iron nanoparticle hybrids produced minimal alteration in the sensory experience of the foods when compared to conventional ferrous sulfate preparations, providing the pleasant smell and taste of oats. These are also highly soluble in water. The study further confirmed, through advanced imaging and spectroscopic analyses (cryo-TEM and XPS), that the OatNF hybrids contained sub-nanometer iron particles, with up to 90% of the iron in the ferrous state, contributing to their exceptional bioavailability and stability.

Breakthrough in iron availability

The current study builds upon prior research by the same authors, which demonstrated the high absorption and bioavailability of ferric phosphate nanoparticles and presented iron nanoparticles as suitable for iron fortification. However, the bioavailability still fell below that of ferrous sulfate, unlike in the present case, where the hybrids had extremely high bioavailability compared to ferrous sulfate.

The scientists also extended their preclinical work on milk-derived protein nanofibril–iron nanoparticles in rats to this human study. They found that the OatNF-iron hybrids achieved 176% of the bioavailability of ferrous sulfate, indicating a significant improvement in iron absorption.

We believe that the plant-based OatNF-SA-Fe hybrids introduced in this work may offer a breakthrough strategy for effective delivery of highly absorbed iron in fortified foods and beverages and may contribute to the mitigation of iron deficiency and anemia on a global scale.

The plant-based nature of this formulation makes it appealing to all dietary groups, including vegans and vegetarians, while maintaining high bioavailability. Moreover, it is shelf-stable, and its manufacture is inexpensive and straightforward.

Next steps for food fortification

This pioneering work demonstrates the exceptionally high performance of oat nanofibril-iron nanoparticle hybrids, making them a potentially ideal solution for iron fortification of foods and beverages.

The OatNF-SA-Fe hybrids showed 176% and 166% relative bioavailability compared to ferrous sulfate when administered with water and polyphenol-rich food, respectively.

These promising results introduce OatNF hybrids as a possible cost-effective, plant-based and organoleptic-friendly solution to the global challenge of iron deficiency anemia.t

Download your PDF copy now!

*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.