Iron fortification efforts boosted by protein-nanoparticle combo

The teasm believe the creation of an iron–amyloid fibril hybrid could be a highly effective delivery system for iron in both solid and liquid matrices. ©iStock

A combination of whey protein nanofibrils and iron nanoparticles could help food and drink formulators provide a sustainable and cost-effective strategy to reduce iron-deficiency.

The Nature study details the use of a hybrid material made up of these nanofibrils, which are combined with iron nanoparticles that can safely be absorbed by the body.

“On examining the organs and tissues of the rats, we did not find any evidence of nanoparticles or nanofibrils accumulating or possibly causing organ changes", said Dr Raffaele Mezzenga, study lead author and head of the Laboratory of Food & Soft Materials at the Swiss Federal Institute of Technology in Zurich (ETH Zurich).

"Our new iron supplement has enormous potential for successfully combating iron deficiency in an economic and efficient way."

The approach uses materials that are cheap and in plentiful supply. Whey proteins, for example are a side-product of the dairy industry and iron salts are also cheap and readily available.

As both the process and the ingredients are easy to work with, this iron food supplement would also help people living in resource-poor countries that are more prone to iron deficiency.

Iron Deficiency Anaemia (IDA) is a major global health problem affecting 2.2 bn people worldwide.

Estimates have placed the average prevalence of iron deficiency in Europe at 5-10%.  

Whilst diagnosed in 4-8% of children between 13-15 years of age, the highest prevalence is seen in women during their reproductive years (20%).

Boosting iron levels through the diet or supplements is tricky, as the iron must be in a form that the body is able to absorb successfully.

The most bioavailable forms of iron tend to turn the colour, taste and smell of food to a much more unappealing form, making it far less appetising.

Iron nanoparticles are also easily oxidized and can clump in solution due to their instability limiting their use in food fortification.

However last year, Nestlé researchers detailed a number of approaches that could help reduce undesirable changes to colour and flavour resulting from the addition of iron.

Iron out compound issues

Led by Dr Mezzenga and Dr Michael Zimmermann, also from the ETH, whey protein was first heated to 90°C (194°F) to form the nanofibrils.

Acid treatment then hydrolysed them into the final protein filaments. The team then combined these nanofibrils with iron nanoparticles - 20 nanometres (nm) in size that instantly bound to the protein nanofibrils surface stabilising the structure.

This compound was then given to iron-deficient rats, which improved the animals' iron deficiency and the associated anaemia just as effectively as iron sulphate (FeSO4), the most commonly-used iron supplement used in humans.

Additional findings found the supplement to be well-tolerated by the animals, which easily digested the whey protein nanofibrils.

In addition, the team also found the iron nanoparticles dissolved into iron ions, which can be absorbed into the blood and used to produce new red blood cells.

“The iron-coated whey protein nanofibrils can be administered either in powder or liquid form, and the new compound can be easily added to different types of food without affecting their taste or smell or colour,” the researchers said.

Safety considerations

From a structural point of view, these structures are similar to amyloid fibrils, which accumulate in the brain and have been linked to Alzheimer's disease.

However, as the researchers point out, the study uses hydrolysed edible food proteins that were found not to accumulate in the body and potentially produce tissue anomalies.

“Feeding the rats with these hybrid materials did not result in abnormal iron accumulation in any organs, or changes in whole blood glutathione concentrations, inferring their primary safety,” the study highlighted.

Although iron oxide nanoparticles have been considered as biocompatible, the influence of nanoparticle surface coating, size, or dose, and of other factors such as treatment time or cell type, has been demonstrated to be significant for iron oxide nanoparticles in vitro toxicity manifestation. 

In vivo studies have shown distribution of iron oxide nanoparticles to different tissues and organs, including brain after passing the blood-brain barrier.

Source: Nature Nanotechnology

Published online ahead of print: doi:10.1038/nnano.2017.58

“Amyloid fibril systems reduce, stabilize and deliver bioavailable nanosized iron.”

Authors: Raffaele Mezzenga and Michael B. Zimmermann et al.


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