Should women on a paleo diet be taking iodine supplements?

By Stephen Daniells

- Last updated on GMT

© Getty Images / nito100
© Getty Images / nito100

Related tags Obesity Iodine deficiency

The paleo diet may increase the risk of iodine deficiency, says a new study that calls for iodine supplementation for people adhering to the growing trend.

Long-term adherence to a paleolithic-type diet, which excludes table salt (which is iodized) and dairy products, led to the development of mild iodine deficiency for healthy postmenopausal Swedish women, whereas women consuming a diet according to the Nordic Nutrition Recommendations (NNR), according to data published in the European Journal of Clinical Nutrition.

“[D]iets used for reducing obesity may have adverse effects that are not immediately recognized,”​ wrote researchers from Kungalv’s Hospital, the University of Gothenburg, and Umeå University in Sweden.

“The iodine issue is an ongoing concern, as is exemplified by the reoccurrence of [iodine deficiency] in the UK, and awareness of new risk groups is necessary. In this study, the low [24-h urinary iodine excretion] in subjects on [paleo diet] confirms for the first time the hypothesis that a [paleo diet] results in a higher risk of developing [iodine deficiency], than a diet according to the NNR. Therefore, we suggest iodine supplementation should be considered when on a [paleo diet].”

Paleo explosion

Interest in the Paleo or ‘caveman’ diet has steadily increased amongst America’s health and fitness fans and the number of food firms directly targeting Paleo is on the rise. The diet encourages eating lean meats, most fruits and vegetables, but no grains, dairy, corn, potatoes or legumes. Putting a number on the actual market is not easy, however, with different data sources quoting different figures, depending on labeling and positioning of products.

For example, IRI data on US retail sales of foods and beverages with Paleo in the name of the product indicated that the market increased 8% to $11.6m in the year to June 11, 2017. The number of products featuring Paleo claims on pack, certified Paleo or referencing Paleo in marketing materials is somewhat higher, and sales could reach $4bn by 2020, Sally Lyons-Wyatt, executive president and practice leader at IRI, told our sister publication FoodNavigator-USA​ earlier this year.

According to SPINS, the largest share of Paleo-positioned products are sold via the natural channel, with US retail sales up 123.4% to $76.8m in the year to May 21, 2017, but the conventional channel experienced the most growth, with sales up 218% to $55.8m over the same period.  Meanwhile, sales in the specialty gourmet channel were up 131.2% to $4.4m.

Mintel data showed 190 paleo-labeled products entered the US food retail market in 2016, which remains very small compared to around 20,000 new food and beverage products launched each year.

The new study brings a new perspective on the issue, and is reportedly the first study to evaluate the impact of the paleo diet on iodine nutrition.

Study details

A 2016 Australian study supported the weight loss potential of a paleo diet, with women adhering to the diet plan losing 4.3% of their body weight and 3.8% of their waist circumference in four weeks (Nutrients, 2016, 8(5), 314; doi:10.3390/nu8050314).However, along with the weight loss in the paleo group came lower intakes of key micronutrients, including lower iodine, sodium and calcium.Image © Getty Images / Rostislav_Sedlacek

The researchers recruited 70 healthy postmenopausal overweight or obese women to participate in their two-year prospective randomized weight loss trial. Women were randomly assigned to consume either the paleo diet or a diet according to the Nordic Nutrition Recommendations (NNR).

At the start of the study, both groups had similar iodine levels, as measured by 24-h urinary iodine concentration (24-UIC) and 24-h urinary iodine excretion (24-UIE). Decreases in both measures were observed in the paleo group, but no changes were observed in the NNR group.

Iodine levels increased again in the paleo group between the six month and two year period, noted the researchers, but levels did not return to the same values seen at the start of the study nor did they reach the levels seen in the NNR group. The increase was attributed to poorer compliance with the actual diet plan the longer the study progressed.

“In this study it is for the first time demonstrated that long-term use of a [paleo diet] is associated with the development of mild [iodine deficiency], whereas a normal iodine status is maintained while on the NNR diet. This occurred during ad libitum intake of both diets and concurrent weight reduction,” ​concluded the researchers.

Source: European Journal of Clinical Nutrition
Published online ahead of print, doi: 10.1038/ejcn.2017.134
“A Paleolithic-type diet results in iodine deficiency: a 2-year randomized trial in postmenopausal obese women”
Authors: S. Manousou et al.

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