After iodine, an iron shot for salt

By M R Gandhi & Team

For several years now, iodine has been a standard ingredient in common salt that we use in India. The presence of iodine has almost eradicated the goitre disease that occurred because of iodine deficiency.

Our team at the CSMCRI has often been asked whether common salt can be fortified with iron as well. Iron deficiency is a common problem in India. Women, especially during pregnancies, need a good dose of iron, which cannot be supplied by a normal diet.

About couple of years ago, we made attempts to add iron supplements to salt. While the process might seem to be a straightforward case of adding a chemical into salt, but that is not the case. When we tried to add iron, we found that the iodine in the salt got destabilised. Iodine is present in salt in the form of Potassium iodate (KIO3). When we tried to add iron, in the form of Ferrous fumarate or Ferrous sulphate (FeSO4), the two compounds reacted to produce another set of compounds that produced a very pungent smell. In addition, while Ferrous fumarate is dark in colour, Ferrous sulphate is greenish. This resulted in a change in colour of the salt.

We had to find a way to prevent the iron and iodine compound from reacting with each other. To tackle this problem we decided to use Magnesium hydroxide Mg(OH)2 molecules. The Magnesium hydroxide has lattice-like structure which traps other molecules and acts like a cage. We decided to use this method for iron and iodine compounds.

In our experiments, we saw that the IO3- ion indeed was getting trapped inside the matrix consisting of layers of Mg(OH)2 molecules. Even the iron, Fe3+++, ion was getting trapped. We, therefore, produced two Magnesium hydroxide matrices, one comprising iodate ions and the other having ferric ions. When the common salt was fortified in this form, the iron and iodate ions don’t come in contact with each other. This method imparted ultra fine stability to the constituents.

The resulting double-fortified salt has cleared animal trials. For this, three sets of mice were starved of iron because of which the haemoglobin in their blood dropped. Then one set of mice were given normal salt, that is available in the markets, and the other set was given the salt which had iron and iodine in the Magnesium hydroxide matrix, and the third set was given iron and iodine salt, without the Magnesium hydroxide matrix.The results showed that the maximum improvement in the haemoglobin levels happened in the mice that were given iodine and iron through the Magnesium hydroxide matrix.

We believe that salt fortification does not need human trials, but we have done that as well. Two trials on batches of 10 candidates each have been carried out and the toxicity results have been normal. Another round of human trials is currently on.

Meanwhile, our laboratory has tied up with the district administration of Bhavnagar to include this salt in the mid-day meal programme.

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