Iron supplements in nano form may be gentler on the gut

Iron deficiency is the most common and widespread nutritional disorder in the world with two billion people – over 30% of the world’s population across both developing and developed countries – suffering from anaemia. As a result, many people take oral iron supplements.

Currently available iron supplements predominantly rely on soluble iron compounds, which can have adverse effects on the gastrointestinal tract leading to constipation and diarrhoea, and these soluble iron compounds can also interact with some medicines and with bacteria in the gut. However, a recently published UK study in the journal Nanomedicine indicates that iron supplements in nanoparticle form might have fewer gastrointestinal side effects than currently available preparartions.

The form of iron found naturally food is called ferritin, and this is less reactive than soluble iron compounds such as ferrous sulphate. Ferritin is therefore less likely to interact with bacteria and chemical compounds in the gut, but it is expensive to extract from food. In this new study, the researchers developed five synthetic formulations of ferritin made up of molecule clusters less than 10 nanometres across. They attached various combinations of organic acids so that the particles would better resemble the version of ferritin found in food.

Having confirmed that nano-iron is non-toxic in cell and mouse experiments, the team tested their different formulations on 26 pre-menopausal women, a group more likely to be lacking iron than the rest of the population. The most promising preparation was iron hydroxide adipate tartrate which, in humans, was 80% as bioavailable as ferrous sulphate, and was effective in replenishing haemoglobin, but without side effects.

Concern is often expressed about the potential toxicity of nanoparticles in the gastrointestinal mucosa. In the rat study presented in this paper, there were no ultra-structural changes in the small intestine tissue or abnormal iron deposition in the intestinal mucosa for the nano ferric material following 14 days of feeding. This is apparently contrary to what has been observed for some soluble ferric iron chelates, leading the authors of the current nano-iron study to suggest that nano iron materials may be safer to the gut than soluble iron. The next step, they say, is to conduct larger trials in a wider range of people, but the hope is that by making oral iron an nano-particulate there exists the potential to make it better tolerated by the human gut.