Iodine in milk

WHEN it comes to iodine content, conventional milk tends to have more compared to organic milk. So says a study conducted by researchers at the University of Santiago de Compostela in Spain. The difference has to do with the diet of the cows reared for milk production.

The concentration of nutrients in animal food products is linked to the diets of the animals reared. Conventional production methods provide mineral diet supplements, whilst in organic farming, animals depend on the mineral content in soil, which may not be sufficient. Hence, the study recommends that animals in organic farms should have their diets supplemented with natural sources of iodine such as seaweed, since iodine is a very important element for children and pregnant women.

Researchers compared the mineral and toxic elements of organic and conventional milk taken from over 30 farms located in the northeast of the Iberian Peninsula. Their findings showed that mineral element content in organic milk is low compared with conventional milk, although there were no differences found in the quantity of toxic compounds such as cadmium, which were also detected in very low concentrations.

“Levels of the elements that are typically supplemented in the diets of livestock in conventional systems – particularly iodine, copper, selenium and zinc – are higher than those found in organic milk,” said Marta López, researcher and co-author of the study.
Not only is organic milk lower in iodine, it is also lower in copper and zinc. However, milk is not the main source of these two elements. But iodine is important since it helps in metabolism, and is a dietary requirement for expectant women and infants. Therefore a source of iodine other than iodised salt is necessary, according to Ms López.

From this study, manufacturers can take their cue to improve the nutrient content of organic milk. But whilst the research shows the inadequacy of organic milk in terms of iodine, it does not necessarily state that conventional milk is better either. “Organic milk may have lower content of certain minerals, but it has other properties that are much more beneficial than those of conventional milk,” Ms López said.