Iron deficiency remains the leading nutrient deficiency in both developed as well as developing countries. It affects around one in five women in the UK.
Many women are encouraged to take supplements but research suggests that these are not always very effective as the body has trouble taking up the form of iron provided.
New research from Fabian Rohner from ETH Zurich, in collaboration with researchers from the University of Zurich, appears to indicate that by reducing one such iron compound, iron phosphate, to the nanoscale, may boost its bioavailability.
"To our knowledge, this is the first study investigating the potential nutritional value of Fe-containing nanoparticles," wrote Rohner in the Journal of Nutrition. "The [iron phosphate] small particles, with a [diameter] of 10.7 nm, demonstrated in vitro solubility and in vivo [relative bioavailability value] equivalent to commercial [iron sulphate]… the reference Fe compound for food fortification for humans."
Rohner and colleagues used the flame spray pyrolysis (FSP) technique to prepare two sets of iron phosphate nanoparticles (average size 30.5 and 10.7 nanometres), and then assessed their bioavailability in iron-deficient rats.
The preparations were found to have similar solubility at low pH to commercially available iron phosphate as well as handling characteristics.
To test the bioavailability of the FSP nanoparticles, male Sprague-Dawley rats were randomly assigned to nine groups, with between nine and 12 rats per group, to consume diets fortified with one of three iron phosphate (two nanoscale preparations plus one commercial preparation at 10 or 20 mg per kg doses), commercial iron sulphate, or placebo (no added Fe).
Rohner and colleagues report that the nanoparticles significantly increased red blood cell haemoglobin and increased body weight gain in iron-deficient rats. The researchers stated that the relative bioavailability value (RBV) of the small nanoparticles (10.7 nm) did not differ significantly from the iron sulphate reference.
"These results suggest that reducing the size of poorly soluble iron compounds to nanoscale may increase their value for human and animal nutrition," wrote the researchers.
No toxicity issues were found by the researchers.
"This study does not suggest absorption of the iron phosphate nanoparticles via paracellular uptake or the lymphatic system… Considering the high solubility of the iron phosphate nanoparticles, they were most likely dissolved during digestion in the intestinal lumen and absorbed through the usual receptor-mediated pathway of non-heme Fe absorption," they said.
Several challenges still exist, most notably questions about whether such research can be replicated in humans, and also whether the nanoscale iron phosphate adversely affects sensorial characteristics when formulated in food.
"Although sensory aspects were not considered in this study, compared with iron sulphate, the iron phosphate nanoparticles may possibly produce fewer adverse organoleptic changes in food vehicles, particularly in colour-sensitive foods, such as rice, salt, milk-based drinks, and highly refined cereal flours," said the researchers.
"However, the sensory characteristics of the Fe nanoparticles needs further investigation."
Source: Journal of Nutrition
March 2007, Volume 137, Pages 614-619
"Synthesis, characterization, and bioavailability in rats of ferric phosphate nanoparticles"
Authors : F. Rohner, F.O. Ernst, M. Arnold, M. Hilbe, R. Biebinger, F. Ehrensperger, S.E. Pratsinis, W. Langhans, R.F. Hurrell, and M.B. Zimmermann
