The concentration of nutrients in animal food products is linked to the diets of the animals reared. Conventional production methods provide mineral diet supplements, while in organic farming animals depend on the mineral content in soil, which may not be sufficient.
For this reason, researchers at the University of Santiago de Compostela compared the mineral and toxic elements of organic and conventional milk taken from over thirty farms located in the northeast of the Iberian Peninsula.
The results demonstrated that mineral element content in organic milk is low compared with conventional milk, although no differences were 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," Marta López, researcher at the University of Santiago de Compostela and co-author of the study, explains.
In the researcher's opinion, the fact that organic milk contains lower levels of elements such as copper and zinc is not a problem because milk is not the primary source of these elements in our diets.
"Iodine is another matter," López goes on to clarify. "The contribution of iodine to our diets in countries like Spain is covered by iodised salt; in other countries, like England, with milk. In Spain the lack of sufficient iodine in some kinds of milk is especially relevant for children, due to the importance of iodine in neurological development, but also to people with diets low in salt."
Iodine is necessary for the metabolism, especially during pregnancy and infancy. Iodine deficiency can cause scurvy, which has historically been a big problem the world over, particularly in populations at a distance from the coast, who did not eat much fish, and so milk and its derivatives were the primary source of iodine.
