Study Examines Iodine Deficiency Risk in Paleo vs. Nordic Diets
The Popularity of the Paleo Diet
A new randomized controlled trial investigates whether the Paleo diet increases the risk of developing iodine deficiency compared to the Nordic diet. The Paleo diet, often referred to as the caveman or stone-age diet, has gained traction as a weight loss approach. Followers of this diet eliminate modern foods and consume items similar to those eaten during the Paleolithic era, primarily consisting of fresh fruits, vegetables, meats, and nuts. This diet excludes grains, legumes, dairy, refined sugars, processed oils, and salt.
Health Claims Surrounding the Paleo Diet
Research indicates that the health claims associated with the Paleo diet may hold some validity. Numerous studies suggest that the elimination of high-fat and processed foods can enhance health. By prioritizing fruits, vegetables, and meat while restricting carbohydrates, the diet may lead to reduced caloric intake. Some studies have reported short-term benefits, such as improvements in waist circumference and blood glucose levels, which could mitigate the risk of chronic diseases. Conversely, others argue that there is insufficient evidence to substantiate the long-term benefits of the Paleo diet.
The Importance of Iodine
Essential Nutrient for Thyroid Function
Iodine is a crucial nutrient necessary for the production of thyroid hormones. It is found in salt, seafood, dairy products, and certain meats. Iodine deficiency is a widespread nutritional disorder linked to various health issues, including goiter, hypothyroidism, and cognitive impairments in infants born to iodine-deficient mothers. Since the 1920s, iodized salt has been widely used in developed countries to combat the prevalence of goiter.
Measuring Iodine Deficiency
The most effective method for determining iodine deficiency in populations involves analyzing urine samples, as iodine is excreted through urine. A median iodine concentration below 50 mg/L indicates mild deficiency, while levels below 20 mg/L signify severe deficiency. Given that individual iodine intake can fluctuate, assessing urinary iodine excretion over several days offers a more accurate iodine status evaluation.
Comparative Study of Iodine Levels
Research Methodology
A recent study published in the European Journal of Clinical Nutrition explored iodine levels in participants following the Paleo diet versus those adhering to the Nordic diet, based on the Nordic Nutrition Recommendations. The Nordic diet emphasizes traditional foods from Nordic countries and recommends an iodine intake of 150 mg/L per day.
The Swedish researchers compared 24-hour urinary iodine concentrations in 49 postmenopausal obese women assigned to either the Paleo or Nordic diet. The study was conducted from 2007 to 2010, with clinical assessments occurring at the study’s onset, six months, and 24 months.
Dietary Composition
The Paleo diet primarily consisted of lean meats, fish, seafood, fruits, vegetables, eggs, and nuts, contributing 30% of energy intake from protein, 40% from fat, and 30% from carbohydrates. This diet excluded dairy, cereals, beans, refined fats, sugars, and added salt. In contrast, the Nordic diet featured lower protein and fat intake but higher carbohydrate consumption, with 15% of energy from proteins, 25-30% from fat, and 55-60% from carbohydrates.
Findings on Iodine Levels
Initial results indicated similar median 24-hour urinary iodine concentrations (71 mg/L) and urinary iodine excretion (134 mg/d) for both diet groups. However, after six months, the Paleo group experienced a decrease in urinary iodine concentration to 36 mg/L and excretion to 77 mg/d, while iodine levels in the Nordic diet group remained stable. Additionally, hormone levels, including FT3, decreased in the Paleo group, though FT4 and TSH levels were comparable in both groups.
Implications of Long-Term Paleo Diet
Potential for Mild Iodine Deficiency
The study underscores that long-term adherence to the Paleo diet may lead to mild iodine deficiency. Participants who initially had sufficient iodine levels became deficient after six months on the Paleo diet. Interestingly, urinary iodine levels increased in the Paleo group by the 24-month mark, possibly due to challenges in maintaining the diet. Consistent with mild iodine deficiency, FT4 and TSH levels remained unchanged.
Significance of the Study
This research is notable as it is the first to examine the link between iodine deficiency and the Paleo diet. Despite a small sample size, the precision of sample collection enhances the study’s strength. The findings suggest that differences in iodine levels between the two diets reflect the true impact of dietary changes.
Recommendations for Paleo Diet Followers
Need for Iodine Supplementation
The study concludes with a cautionary note regarding the potential adverse effects of restrictive weight loss diets. The resurgence of iodine deficiency in the UK exemplifies the iodine challenges associated with the Paleo diet. The observed low urinary iodine concentrations in participants following the Paleo diet confirm an increased risk of iodine deficiency. Researchers recommend that individuals adhering to the Paleo diet consider iodine supplementation to maintain healthy iodine levels.
Citation
Written by Preeti Paul, MS Biochemistry. Reference: S Manousou et al. “A Paleolithic-type diet results in iodine deficiency: a 2-year randomized controlled trial in postmenopausal obese women.” European Journal of Clinical Nutrition (2018) 72, 124-129; doi:10.1038/ejcn.2017.134.