Organic Milk Consumption during Pregnancy Could Lead to Lower IQ for Baby Later in Life, Study Says

pregnant bellyPeople who drink organic milk do so for a number of reasons. For some, it’s about health. For others, it’s about the treatment of animals. But whatever the reason, there may be a difference between organic milk and “regular” milk that they hadn’t counted on – lower levels of iodine. A recent study suggests, for pregnant women, that one difference could lead to lower IQs for their children later in life.

Important for the production of hormones made by the thyroid, iodine is extremely important during pregnancy because it can have a direct effect on fetal development. Studies have linked serious deficiencies to cretinism (the medical term for retardation), but even mild or moderately deficient can bring harm to their unborn baby, the recent study says.

Published in The Lancet, this study was the first to look at the effects of mild to moderate iodine deficiencies during pregnancy. The researchers, from Surrey and Bristol University, measured the iodine in urine samples or 1,040 during the first three months of pregnancy. Two-thirds were found to be deficient, and their children were more likely to have low scores in verbal IQ, reading accuracy and reading comprehension tests when compared to those that had adequate iodine levels during pregnancy. Overall, their children had a 60 percent higher risk of lower scores and poor reading abilities by ages eight and nine.

Study founder Professor Jean Golding believes it’s likely that this lack of achievement would carry on throughout the child’s life. She added that those who were unable to “achieve their full potential” might end up having lower exam grades, particularly GCSE and A level exams.

“Our results clearly show the importance of adequate iodine status during early pregnancy, and emphasize the risk that iodine deficiency can pose to the developing infant, even in a country classified as only having mildly iodine deficient,” Golding told Daily Mail UK.

Co-author Dr. Sarah Bath told Daily Mail UK that women planning to become pregnant, those who are pregnant and those that are breastfeeding should make sure they have an adequate intake of iodine from natural food sources. She warned that kelp supplements should be avoided since they may have excessive iodine levels, which could be harmful.

Iodine is naturally found in milk, yogurt and oily fish. But for whatever reason, this study indicated that organic milk contains less iodine. However, they pointed out that the iodine content of skim and full-fat milk are the same. In most countries, iodine can also be found in regular table salt. It is not, however, contained in most brands of Sea Salt.

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About the author


Kate Givans is a wife and a mother of five—four sons (one with autism) and a daughter. She’s an advocate for breastfeeding, women’s rights, against domestic violence, and equality for all. When not writing—be it creating her next romance novel or here on Growing Your Baby—Kate can be found discussing humanitarian issues, animal rights, eco-awareness, food, parenting, and her favorite books and shows on Twitter or Facebook. Laundry is the bane of her existence, but armed with a cup of coffee, she sometimes she gets it done.


  • There are scientifically proven health and sustainability benefits of organic milk which are valuable as part of a balanced and healthy diet. Studies show that organic whole and semi-skimmed milk has more beneficial omega-3 fatty acid, Vitamin E and beta-carotene than non-organic milk and studies by Glasgow and Liverpool Universities found that UK organic milk has 68% higher levels of the essential fatty acid than non-organic milk.

    Pregnant women should not stop drinking organic milk in response to a study published in the Lancet today highlighting iodine deficiencies in pregnant women and citing lower levels of iodine in organic milk.

    The Soil Association is aware of potentially lower levels of iodine in organic milk and we are working with farmers and scientists to find ways of addressing this issue whilst keeping all the other benefits consumers rightly expect.

    There are variations of levels of iodine in milk which are unrelated to whether or not it is organic. According to The Dairy Council there are seasonal variations – winter milk, may contain slightly higher levels of iodine than summer milk. It also seems that levels of iodine range sharply depending on whether it is high or low fat milk (British Journal of Nutrition)”

    The fact that organic cows have a natural grass based diet, and do not routinely receive supplements may explain why iodine levels are potentially lower in organic milk. Organic milk is the most researched organic food with significant findings in favour of its nutritional value. Organic milk and dairy products contain more beneficial nutrients than non-organic because organic cows eat more grass.

    • Talk about a misleading title! “Organic Milk Consumption during Pregnancy Could Lead to Lower IQ for Baby Later in Life, Study Says” That’s absurd! And not at all what the “study says”; that is what the author has chosen to say about the study. It’s no secret that organic milk has less iodine in it – iodine is added to commercial animal feed, which organic cows don’t eat. The original study is helpful in understanding the importance of iodine during pregnancy, but this author’s spin on it is irresponsible.

  • I understand that you feel the title and the information is deceptive.

    I relate with the desire to avoid the hormones and cruel treatment of animals. It’s for these reasons (as well as others) that our family chooses to consume organic soy and rice milk.

    When writing this post, I’d also felt that the news source had kind of plugged it in there on their own accord. Unfortunately, because the actual study wasn’t linked, I had no way of verifying whether or not organic milk was actually linked in the study. And because it is a news source, I didn’t want to leave any pertinent information out.

    I apologize for any confusion.

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