Iodine is instrumental in the creation of thyroid hormones, which normalize metabolism, development, and growth, from birth right up to the end of life. Accordingly, iodine deficiency can have negative effects on brain function, fertility, and child development.
This nutrient can be found in foods such as seaweed, fish, iodized salt, dairy products, and some fortified grains. It can also be taken as a dietary supplement.1,2
Studying Iodine Status and Associated Factors Across Canada
In the Prospective Urban and Rural Epidemiological (PURE) study, researchers studied iodine deficiency in 800 adults across Vancouver, Hamilton, Ottawa, and Quebec City, as well as potential risk and protective factors associated with iodine deficiency.1
Urine samples were collected over 24 hours and examined for iodide and sodium, which are reflective of iodine and sodium intake, respectively. During these 24 hours, participants also documented foods they had consumed, as well as aspects of medical history and lifestyle.
The researchers found evidence of iodine deficiency in 25.3% of the participants – 16.6% of participants had moderate to severe deficiency. On the contrary, excessive iodine intake was evident in 31.3% of participants.1
Factors that were associated with sufficient iodine intake included iodine supplementation, thyroxine use, dairy intake, and sodium intake. Consuming bread and cereal was also slightly associated with iodine sufficiency. Factors that were associated with iodine deficiency included alcohol and tobacco use.1
The researchers also found that iodine deficiency was different depending on where the participants were living. They suggest that this may be due to variations in iodine found in dairy products across the country, depending on farming practices in each particular location.1
Thiocyanate and Nitrate
Thiocyanate and nitrate decrease the body’s ability to absorb iodine. Thiocyanate is produced by the body and found in tobacco products and some vegetables, while nitrate is abundant in leafy green vegetables. To determine the level of exposure to these compounds, the researchers measured thiocyanate and nitrate levels in participants’ urine samples1.
Like iodine status, exposure to thiocyanate and nitrate also varied among the four urban centers. Thiocyanate exposure was associated with tobacco use while nitrate exposure was associated with vegetable consumption. The researchers indicated that thiocyanate and nitrate intake may be another contributing factor to iodine deficiency1.
Based on the results of this study, iodine status was satisfactory in the majority of participants. Iodine deficiency was associated with lower consumption of dairy products and sodium and greater exposure to thiocyanate and nitrate. Based on these findings, the researchers pointed out that plant-based and/or low sodium diets may pose a risk for iodine deficiency, demonstrating a need for further optimization of national food guides.1
While this study provided some insight into iodine statuses and associated factors across Canada, the researchers acknowledged that future studies evaluating these factors in a broader population, including children and pregnant women, will provide a more accurate representation. Moreover, the researchers have indicated that studying other potential sources of iodine and nitrate, such as drinking water, will provide additional information about protective and risk factors associated with iodine deficiency.1
1. Mathiaparanam et al. (2022, June 21). The Prevalence and Risk Factors Associated with Iodine Deficiency in Canadian Adults. Public Health Nutrition and Healthy Aging 14(13), 2570;
2. McMaster University (2022, July 7). Iodine status varies across Canada, raising deficiency risk in some regions.
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