Iodine in Ukraine: why iodized salt still matters

The thyroid needs iodine to make its hormones. A lack of it early in life impairs growth and brain development, and in adults it is a key factor in thyroid disease (Zimmermann, Boelaert, 2015). Ukraine has long been among the regions where food is low in iodine — and research shows the problem still hasn’t been solved.

How much iodine Ukrainians get

The largest dataset comes from the Ukrainian-American study of the Chornobyl accident’s consequences: urinary iodine was measured in almost 12,000 people from regions affected by the accident. Between two screening cycles the median rose from 41.7 to 47.5 µg/L, but stayed in the mild-to-moderate deficiency range by WHO criteria. Iodine was lower in villages than in towns (Tronko et al., 2005).

Pregnant women are the most vulnerable: iodine needs rise during pregnancy. In Zhytomyr, 148 women up to 16 weeks pregnant were tested: their median urinary iodine was just 13 µg/L — versus 62 µg/L in non-pregnant women — and in 95.9% it was below 150 µg/L, meaning their intake was insufficient. The authors call this severe deficiency (Sekitani et al., 2013).

Why even mild deficiency is a problem

Severe iodine deficiency causes goitre and hypothyroidism. In mild-to-moderate deficiency the thyroid can usually compensate by working harder — but at a price: over the years, nodular goitre and hyperthyroidism become more common in such populations (Zimmermann, Boelaert, 2015).

A developing child’s brain is especially sensitive to iodine. The British ALSPAC study analysed 1,040 mother–child pairs. Children of women who were low in iodine in the first trimester were more likely to score in the bottom quarter for verbal IQ at age 8 (odds ratio 1.58), and for reading accuracy (1.69) and comprehension (1.54) at age 9. The lower the mother’s iodine, the worse the scores — in a country considered only mildly iodine deficient (Bath et al., 2013).

Ukraine has one more reason to remember iodine. A study in Belarus and Russia after Chornobyl found that the risk of thyroid cancer from radioactive iodine received in childhood was three times higher where ordinary iodine was lacking, and that taking potassium iodide cut this risk threefold (Cardis et al., 2005). A thyroid short of iodine takes up any iodine more eagerly — radioactive iodine included.

The salt that could solve it

The best-proven approach is to iodize all food-grade salt: both the salt in your shaker and the salt used for bread, cheese and sausages. In 2000–2009, 13 of the 15 successful countries in Central and Eastern Europe and the former USSR made such iodization mandatory. Voluntary iodization, or iodizing only household salt, worked less well. The review’s authors named weak political leadership in Russia and Ukraine as the main reason the region lagged behind (van der Haar et al., 2011).

More and more of our salt comes from processed foods rather than the shaker. A study in five countries, Ukraine among them, estimated that if manufacturers use iodized salt, a day’s worth of bread or another popular product alone can supply 10% to 80% of the recommended iodine intake (Knowles et al., 2017). So it matters which salt the bakery buys, not just which salt you buy.

WHO advises adults to eat less than 5 g of salt a day — about a teaspoon — and also stresses that all the salt we consume should be iodized. The two pieces of advice don’t conflict: use less salt, and choose iodized. Rules differ from country to country, so if you live outside Ukraine, it’s worth checking whether salt where you live is iodized — and whether that’s mandatory or voluntary.

Does iodine disappear during cooking?

Partly, yes. Researchers in India measured how much iodine from iodized salt is lost with different cooking methods: from 6.6% to 51%. The least was lost in quick shallow frying, when the salt was on the heat for just over a minute, and the most in a pressure cooker, where it stayed for 26 minutes. Boiling lost 40%, microwaving 27%, roasting and deep frying about 10%. The authors concluded that losses depend on the cooking method and on when the salt is added (Rana, Raghuvanshi, 2013). So it’s best to salt long-cooked dishes towards the end.

Why the calculator can’t count iodine precisely

The USDA database we take food composition from lists iodine for only a handful of items — for example, milk and plain yogurt. So the calculator shows iodine but leaves it out of the “consistently short” list: with data this sparse, the daily total would be too low. For most of us the main source of iodine is iodized salt, and the calculator can’t see it.

Can you overdo it? When iodine intake rises in a deficient population, hyperthyroidism becomes temporarily more common, along with a small increase in subclinical hypothyroidism and autoimmune thyroid disease (Zimmermann, Boelaert, 2015). So taking iodine tablets “just in case” without a reason isn’t a good idea. If you’re pregnant or planning a pregnancy, discuss iodine with your doctor.