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16 February 2016

New study published in the British Journal of Nutrition finds lower iodine in organic milk

A study published today has reviewed the evidence for the nutritional difference between organic and non-organic milk. 

By combining the results of 196 individual studies, the researchers can estimate the overall difference – this is called a meta-analysis. The full study can be found here. The results show that organic milk contains less iodine than non-organic milk but that organic milk contains more omega-3 fatty acids.


How do the iodine figures relate to a glass of milk?

  • According to figures published in the new paper, a glass (200ml) of non-organic milk is estimated to contain 29.4 μg, whereas a glass of non-organic milk is estimated to contain 49.6 μg.
  • In relation to the adult requirement of 140 μg/day, this means that a glass of organic milk would provide 21% of the requirement, but a glass of non-organic milk would provide 35%.
  • In other words, a glass of non-organic milk would provide 14% more of the adult requirement than a glass of non-organic milk.
  • This is true whether the milk is full-fat, semi-skimmed, or skimmed.


What about the potential for additional omega-3 fatty acids in organic milk?

  • The researchers have reported that 500ml of full-fat organic milk would provide 16% of the requirement for long-chain omega-3 fatty acids, but 500ml of full-fat non-organic milk would provide 11%. In other words, organic milk would provide 5% more of the requirement for long-chain omega-3 fatty acids than non-organic milk.
  • However, if these figures are calculated on the basis of a glass of milk (200ml), organic milk would provide an additional 2% (6.4% compared to 4.4% in non-organic) of the daily requirement for long-chain omega-3 fatty acids.
  • As the majority of consumers drink semi-skimmed milk, it is likely that the difference would be smaller than the 2% calculated using the figures for full-fat milk.


What if you choose to drink organic milk?

  • There are many reasons why consumers may choose organic milk, and these might not be focussed on nutritional differences.
  • Milk and dairy products are the main source of iodine in the UK diet. Organic milk can still contribute towards the daily iodine requirement but if organic milk is chosen, the lower iodine concentration needs to be kept in mind.
  • Consumers should ensure that they are likely to meet their iodine requirement. Information on alternative sources of iodine is in our fact sheet.