We all need it. I remember reading that it is in certain soils, especially those near the sea. I grow vegetables on land about 100 miles from the sea. Will the soil contain iodine, and therefore be transmitted to the vegies?
We only need a tiny amount of iodine in the diet, you know. I wouldn’t be worrying about it. The chances are you are getting plenty of it anyway, certainly if you use iodized salt, and very probably even if you don’t.
I do not think the vegetables themselves need it at all. It is only needed in humans and other animals because it is a component of thyroid hormone.
I do not think it is possible to say whether your soil contains iodine without actually testing your soil. The chances are that it does - before salt was iodized, thyroid deficiency due to lack of iodine was quite rare and confined to specific local areas (in a time when, unlike now, people mostly ate entirely locally produced food) - but, as I say, it does not really matter.
it is added to commercial table salt (iodized salt) to prevent deficiencies.
Not all soils and not all plants contain sufficient iodine to meet human needs.
Plants in general do not require iodine as a nutrient (see list of nutrients here) and food grown in iodine-poor soils is linked to human deficiencies of iodine:
Most global maps of iodine deficiency that I have been able to find categorize the level of human iodine deficiency by country (like this one.) But you may be able to get detail of you area’s soils from your local department of agriculture or agricultural extension office. Different types of soils have differing likelihoods of iodine deficiency. You may find that if you are in an area with sandy soils that have little clay content or are water-logged (with freshwater, not seawater); then you are in an area likely to have low soil iodine concentrations. If you are in an area with lots of peat, rich in organic matter, and alkaline or pH-neutral soils, than you are in an area likely to have high soil iodine concentrations. See mostly UK- and Ireland-relevant discussion here.
In the United States, I seem to recall something about Great Lakes region soils being unusually low in iodine, but definitely either find out for your local area or test the soils in your area for iodine.
Well, on the map, looking good. I’m in Spain. Just a note, lately I have taken to using Himalayan Salt, which I think does not contain iodine.
There seems to be a fair amount of Iodine in seaweed if you want to enhance the dietary intake.
My dad used to use a lot of seaweed as a compost in his vegetable gardens and claimed it increased the Iodine content of the vegetables that he grew.
This may or may not be true but sounds like a possibility.
His garde was beside a tidal river and he collected the seaweed from there at low tide so it was highly convenient for him if nothing else.
He never suffered from Iodine deficiency either, as far as I can tell.
It does appear to be readily available in quite common foods though.
I would have thought that using seaweed would introduce too much salt into the vegetable garden soil …