Iron transporter discovered; major impact for supplements
has identified for the first time a molecule responsible for
absorption of the mineral in the gut.
The scientists from King's College London who discovered the transporter of the haem form of iron - the type found in animal tissues - say they will be able to learn why iron is so well absorbed from meat and transfer this knowledge to synthetic forms of iron.
Haem iron is absorbed around five times more efficiently than the inorganic iron from plant sources and is therefore better at preventing deficiency.
The British researchers reported in Friday's issue of Cell (vol 122, pp789-801) that the transporter, called HCP1 (haem carrier protein), is expressed in the first part of the intestine, the duodenum.
They found that the protein shifted position within the intestinal cells in response to changes in the body's iron stores, allowing cells to take up more or less haem as required.
"This is the first transporter that has been shown to be involved in haem uptake. Finding this molecule helps us to understand how haem iron is so readily absorbed," said Dr Andrew McKie, who led the research team.
Their work is significant because 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 especially 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.
"Currently pregnant women suffering from anaemia are given supplements of inorganic iron, but these are poorly absorbed in the gut and can have unpleasant side effects," said Dr McKie.
"Having identified the haem transporter scientists can now create in vitro tests of how well synthetic versions of haem iron are absorbed, which could lead to much more effective iron supplements being produced."
Better bioavailability of supplements would not only help tackle iron deficiency and related diseases like anaemia but could also improve treatment of hereditary diseases such as haemochromatosis that cause people to absorb too much iron from the diet.
Recent studies of northern Europeans have shown that around one in 400 are likely to be at risk of developing iron overload.
Mutations in HCP1 are likely to affect the body's ability to absorb haem, noted the researchers, and therefore make it a potential culprit in haemochromatosis. Drugs that inhibit HCP1 could be used to reduce some of the symptoms of this disorder.
