Not getting enough iodine when kids are growing can hurt their brain development for good, because iodine is needed to make important brain hormones.

We don't have strong enough proof to say whether mild or moderate iodine deficiency really affects thyroid function, because the studies done so far aren't very reliable or consistent.

For kids, teens, and adults, not getting quite enough iodine doesn’t seem to clearly affect thyroid hormone levels — some studies see no change, others see mixed results, so we can’t say for sure either way.