Despite what you may think organic does not mean more nutritious, at least when it comes to milk. That was the take home message from a paper published in the Journal Food and Chemical Toxicology.
The Organic label relates to the welfare of the animals and non use of chemical sprays, not to nutritious content. It turns out that some of our much needed trace elements such as iodine, are present in non organic milk due to supplementation of the food we give them.
Iodine is important in areas far from the sea and milk can be the main source of iodine in these areas. It is very important during pregnancy and for women breast feeding. Deficiencies in iodine can cause severe fatigue or lead to a swelling of the thyroid gland called goiter. Iodised salt is one simple way to ensure you are getting enough and is widely available.
One interesting observation in the paper was a very large value of iodine recorded in one sample of conventional milk. It is thought this came from the use of iodine as a sterilising agent on the teats of the cows.