Iodine deficiency might be making a comeback, but not in Hamilton, Mac study finds

A new study by McMaster researchers brings good news to Hamiltonians: residents in Hamilton and Ottawa have sufficient iodine levels compared to those in Vancouver and Quebec City.

According to the study, which analyzed urine samples from 800 individuals, including 217 in Hamilton, Hamiltonians showed good iodine levels. This is likely due to daily dairy consumption and low exposure to environmental iodine uptake inhibitors - perchlorate, thiocyanate, and nitrate - which prevent the body's absorption of iodine, researchers say.

Both Hamilton and Ottawa residents tend to have a great correlation with their self-reported dairy consumption. The more dairy they consumed each day, the higher their iodine status," said Philip Britz-McKibbin, a professor at McMaster and the lead author of the study.

But that's not the case everywhere.

The research, which was published in the journal Nutrients, shows that where you live can have an impact on your iodine intake, and that iodine deficiency might be making a comeback as people change how they eat. Individuals from Vancouver and Quebec City showed higher risk for iodine deficiency due to high iodine uptake inhibitors.

Britz-McKibbin said the paradox is that even though individuals from Quebec City consume more dairy on average, there is a difference in the source of the dairy. Due to sanitation practices when milking cows, iodine-based antiseptics are used on the teats of the cows between milking and leak into the milk supply.

Within Canada the iodine content is quite variable from region to region, and our data suggests, we don't have direct evidence of that, the milk supplies from the cities in Ontario examined tend to have a stronger association of iodine status and dairy intake, which we didn't find in Vancouver and Quebec City," said Britz-McKibbin.

Other contributing factors could be more people following vegetarian or vegan diets or using noniodized salt products, eating more processed foods, and trying to reduce sodium intake.

Britz-McKibbin explained iodine plays an important role in many health functions especially during pregnancy and for childhood development, and a low iodine intake can cause irreversible cognitive impairment in children.

Beatriz Baleeiro is a reporter at The Hamilton Spectator.bbaleeiro@torstar.ca