Iodine fortification may hurt longevity for some older adults
20 Nov 2021
Iodine fortification appears to contribute to increased mortality risk among older adults with a history of hyperthyroidism and moderate iodine deficiency, as reported in a recent study.
The retrospective study used data from Danish registries and included 68-year-olds from the general population in the city of Randers in Denmark. All participants completed a questionnaire and underwent physical examination and blood and urine sampling at baseline (1988). They were followed through 2017.
Median urinary iodine concentration at baseline was 42 µg/L, which was consistent with moderate iodine deficiency. Hyperthyroidism (thyrotropin <0.4 mIU/L) was detected in 37 (9.1 percent) participants.
Kaplan–Meier survival curves revealed an increase in mortality among participants with hyperthyroidism after iodine fortification. Hyperthyroidism had no significant association with mortality prior to iodine fortification compared with normal thyroid gland function.
Following iodine fortification, however, mortality increased for hyperthyroid than euthyroid participants (adjusted hazard ratio, 2.22, 95 percent confidence interval, 1.44–3.44).
There was a transient rise in hyperthyroidism that ensued following the introduction of iodine fortification of salt in Denmark. The findings of the present study underscore the need for cautious and monitoring of iodine supplementation. This is important as older adults are at risk of complications to hyperthyroidism that could prove fatal to vulnerable individuals.