In the June 29th, 2006 issue of The New England Journal of Medicine, researchers from China followed three groups of people with differing intakes and excretion levels of iodine. What they found was startling. People with excessive and more than adequate intakes of iodine had a higher incidence of subclinical hypothyroidism than did those with low intakes. The upper groups also had a higher incidence of auto-immune thyroiditis as well. The group with mildly deficient iodine intake seemed to do best.
A couple of comments here. First off, as is typical with medical research, only one item was looked at and that was the relationship between iodine and thyroid function which is myopic and counter to the complexity of human biochemistry. Did they look at the interactions with protein intake, especially tyrosine competency? Did they look into the availability of selenium in the diet? Of course not. Instead they made a sweeping statement that excessive iodine can cause hypothyroidism and even hinted that too much iodine can cause thyroid cancer. This then is taken by the media to be gospel and public health officials will make decisions based on incomplete science.
If the concept of metabonomics is utilized as it should be, then personalized judgements of the need for iodine would be on a biochemically individualized basis instead of population based guesswork. Medicine needs to catch up to science before more damage to the public’s health is done.
What is important about this study is that blanket statements that everyone needs iodine is potentially dangerous as you may induce hypothyroidism instead of preventing it. Back to biochemical individuality if you ask me.