The scenarios - the iodine intake if household salt and industrial salt used in bread

This section answers question 2 in the terms of reference: What would the iodine intake in the general population and among identified risk groups be if household salt and industrial salt used in bread were to be iodized and if plant-based milks were to be fortified with iodine levels comparable to those in cow’s milk? The iodine intakes resulting from the various scenarios should be estimated both with and without the added effect of iodine fortification of plant-based alternatives to dairy products (milk 15 μg/100 g). The estimates should also be considered in the context of the Salt Strategy 2015 (governmental initiatives to reduce salt consumption).

The scenario estimates for all age groups not using iodine containing supplements are presented in Tables 7.4-3 - 7.4-14.

We have presented 12 scenario tables, three scenarios (household salt alone, salt in bread alone and both household salt and salt in bread) for each iodization level (15, 20, 25 and 50 mg iodine per kg salt). In the text below, we present only the scenarios for iodine added to both household salt and industrial salt used in bread, since the scenarios with iodine only in

VKM Report 2020: 05 166 household salt or only in industrial salt used in bread do not increase the iodine intakes in the groups at risk of low intakes, sufficiently.

The percentages of the population groups with intakes above the EAR increase with increasing iodization levels, but so do also the percentages with intakes above the ULs for iodine.

The scenarios –adults, 13-, 9- and 4-year-olds, the general population In Tables 8.2.1.1-1 and 8.2.1.1-2 we have presented how the estimated iodine intakes in the groups at risk of low intakes (women 18-45 years and 13-year-old girls) increase with the increasing iodization level scenarios.

The iodization option yielding the combined lowest proportions of the population below EAR and above UL, is the scenario of adding 15 µg iodine per kg salt to both household salt and salt in bread. At this iodization level, 93-100% of all adults and adolescents have iodine intakes above EAR and the proportion exceeding UL is ≤ 1%.

At this scenario, 94% of women 18-45 years have estimated iodine intakes above EAR.

Estimated mean (median) intakes are 176 (166) µg/day, and the estimated iodine intake in the 5th percentile is 97 µg/day.

In the same scenario, 93% of the 13-year-old girls have estimated iodine intakes above EAR.

Estimated mean (median) intakes are 132 (122) µg/day and the estimated intake in the 5th percentile is 70 µg/day.

At the scenario of adding 20 µg iodine per kg salt to both household salt and salt in bread, 97% of the women (18-45 years) and 13-year-old girls have estimated intake levels above EAR. The estimated mean intakes are 189 and 145 µg/day in women (18-45 years) and 13-year olds, respectively, and the intakes in the 5th percentiles are 107 and 80 µg/day.

At the scenario of adding 25 µg iodine per kg salt to both household salt and salt in bread, the estimated intake in the 5th percentile has increased to 90 µg/day in the 13-year-old girls.

At the scenario of adding 50 µg iodine per kg salt to both household salt and salt in bread, all age-groups have estimated iodine intakes above the EAR. All the women still have

estimated intakes below the UL, however, 1-20% of the men and children are exceeding UL.

The scenario estimates for the different iodization levels in adults including iodine supplements (users only) are presented in Table V-2 in Appendix V.

The scenarios – 2-year-olds, the general population

For 2-year-olds, all scenarios lead to a decrease in the proportion of children expected to be within the acceptable range. While iodization of both household salt and bread lifts the children with low iodine intake over the EAR, a larger part will have intakes exceeding the

VKM Report 2020: 05 167 UL. At the highest iodization scenarios including iodization of salt in bread (salt+bread50), the proportion of children expected to exceed the UL rises to 63%.

At the scenario of adding 15 µg iodine per kg salt to both household salt and salt in bread, 17-19% of the 2-years-olds have iodine intakes exceeding UL, and the estimated iodine intake in the 95th percentile is 250 and 252 µg/day in girls and boys, respectively. At the scenario of adding 20 µg iodine per kg salt to both household salt and salt in bread, 21-23%

of the 2-year-olds exceed UL, and the estimated iodine intake in the 95th percentile is 259 and 263 µg/day in girls and boys, respectively. At the scenario of adding 25 µg iodine per kg salt to both household salt and salt in bread, 25-30% of the 2-year-olds exceed UL, and the estimated iodine intake in the 95th percentile is 271 and 273 µg/day in the girls and boys, respectively. At the scenario of adding 50 µg iodine per kg salt to both household salt and salt in bread, 57-63% of the 2-year-olds exceed UL.

In the bread15 or bread20-scenario, the proportion of 1-year-olds exceeding the UL increases from 18% to 32 or 36%, respectively. In the bread15-scenario, the estimated iodine intake in the 95th percentile of 1-year-olds is 302 µg/day, and in the bread20-scenario, the iodine intake in the 95th percentile of 1-year-olds is 316 µg/day.

The scenarios – other specified risk groups of low and high iodine intakes.

There was no information available from the national dietary surveys to calculate the effect of the different iodization levels on the iodine intakes in the other specified groups at risk of low iodine intakes levels such as e.g. persons with allergy or intolerance to fish, milk or dairy products, vegans, vegetarians and some ethnic minorities. However, as salt consumption is assumed to be correlated with energy intake, the increase in iodine intake with increasing levels of iodized salt may be expected to be similar in these potential risk groups as in the rest of the population, although with large individual variations within the different groups.

In addition, we do not have exact data on bread consumption among persons in these specified groups at risk. The variation in bread consumption among persons with allergy or intolerance to fish, milk or dairy products, vegans, vegetarians and some ethnic minorities may be assumed to be fairly similar to the variation in bread consumption in the general population. Consequently, for persons with few iodine sources in the diet (low milk in take), vegans and people with allergy or intolerance), the increase in iodine intake in these

potential risk groups may be the same as the increase in the lower percentiles in the scenarios, e.g. the 5th percentiles in the scenarios in Tables 7.4-3 - 7.4-14.

Groups at risk of high iodine intake might be individuals consuming dried kelp or kelp

supplements. In pregnant women, an abrupt moderate increase in iodine intake may cause a transient thyroid stunning effect, with a transient inhibition of maternal or fetal thyroid hormone production.

VKM Report 2020: 05 168 Plant-based alternatives to cow’s milk

This section responds to the following in the terms of reference: The iodine intake resulting of the various scenarios should be estimated both with and without the added effect if plant-based alternatives were to be fortified with iodine levels comparable to those in cow’s milk i.e. 15 µg per 100 g.

The suggested iodine level in plant-based alternatives to cow’s milk corresponds to the concentration in cow’s milk. The national dietary surveys have not collected information on use of plant-based milk alternatives. The project group has, due to lack of intake data, assumed that consumption of plant-based milk alternatives replaces consumption of cow’s milk, and that consumption of plant-based alternatives have similar individual variations as for cow’s milk. The tables presenting iodine exposure in sections 7.3 and 7.4 are therefore applicable for both cow’s milk users and users of the plant-based alternatives given that all plant-based alternatives have the same iodine content and bioavailability as cow’s milk.

Iodization of plant-based alternatives may contribute to increased iodine intake in vegans.

Individuals with low consumption of plant-based alternatives will receive only small amounts of iodine from this source, whereas high-consumers will receive larger amounts. The risks related to high iodine intakes from iodized plant-based alternatives are not considered to be any larger than risks related to milk consumption in any age groups.

Effect of potential salt reduction on the scenario estimates for iodine

This section responds to the following in the terms of reference: The iodine intake estimated should also be considered in the context of the Salt Strategy 2015 (governmental initiatives to reduce salt consumption).

The main goals in the Salt Strategy are 30% relative reduction in mean population intake of salt/sodium within year 2025 and a long-term target of mean salt consumption of 5 g/day.

An intermediate objective is to reduce salt in bread to 0.9 g salt per 100 g bread. This corresponds to approximately 18% reduction in salt in bread compared to our scenario calculations.

A 30% reduction in salt consumption would imply a need for approximately 40-45%

increased iodization levels to achieve the same levels of daily iodine intake as given in the scenario Tables 7.4-3-7.4-14 for all the age groups (1/(1-0.3) = 1.43). This estimate assumes a uniform 30% reduction, and no consideration is given to whether the salt reduction is unevenly distributed between various food groups. Similarly, a reduction of salt in bread to 0.9 g salt per 100 g bread, would imply a need for approximately 22% increased iodization levels to achieve the same levels of daily iodine intake as given in the scenarios.