# iodine **URL:** \ **Category:** Factual Questions\ **Created:** [July 5, 2012, 2:07pm UTC](https://boards.straightdope.com/t/iodine/627308 "2012-07-05T14:07:04Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![bardos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bardos/32/1069_2.png) [@bardos](https://boards.straightdope.com/u/bardos)\ **Post date:** [July 5, 2012, 2:07pm UTC](https://boards.straightdope.com/t/iodine/627308/1 "2012-07-05T14:07:04Z")
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? ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [July 5, 2012, 2:51pm UTC](https://boards.straightdope.com/t/iodine/627308/2 "2012-07-05T14:51:40Z")
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. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [July 5, 2012, 2:52pm UTC](https://boards.straightdope.com/t/iodine/627308/3 "2012-07-05T14:52:30Z")
it is added to commercial table salt (iodized salt) to prevent deficiencies. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [July 5, 2012, 4:01pm UTC](https://boards.straightdope.com/t/iodine/627308/4 "2012-07-05T16:01:44Z")
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](http://aesl.ces.uga.edu/publications/plant/Nutrient.htm)) and food grown in iodine-poor soils is linked to human deficiencies of iodine: > [@University of Michigan Health System](#): > > Is iodine deficiency common in the United States? > > Iodine deficiency is now rare in the U.S. as a result of widespread distribution of foods from iodine sufficient areas. The incidence of iodine deficiency occurs in certain geographical areas at higher altitudes with iodine depleted soil - usually in areas away from the seacoast and in countries where salt is not fortified with 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](http://www.iodinedfcsolutions.co.uk/resources/global-iodine-deficiency-sm.jpg).) 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](http://books.google.com/books?id=dUzceto6yjkC&lpg=PA421&ots=pgMlgRFqIX&dq=%22soil%20type%22%20%22iodine%20deficiency%22&pg=PA421#v=onepage&q=%22soil%20type%22%20%22iodine%20deficiency%22&f=false). 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](http://www.ehow.com/how_6734206_test-iodine-soil.html). ---
**Author:** ![bardos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bardos/32/1069_2.png) [@bardos](https://boards.straightdope.com/u/bardos)\ **Post date:** [July 5, 2012, 4:22pm UTC](https://boards.straightdope.com/t/iodine/627308/5 "2012-07-05T16:22:09Z")
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. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [July 5, 2012, 6:32pm UTC](https://boards.straightdope.com/t/iodine/627308/6 "2012-07-05T18:32:44Z")
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](http://www.whfoods.com/genpage.php?tname=nutrient&dbid=69) though. ---
**Author:** ![purplehorseshoe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/purplehorseshoe/32/2996_2.png) [@purplehorseshoe](https://boards.straightdope.com/u/purplehorseshoe)\ **Post date:** [July 5, 2012, 10:33pm UTC](https://boards.straightdope.com/t/iodine/627308/7 "2012-07-05T22:33:13Z")
I would have thought that using seaweed would introduce too much salt into the vegetable garden soil … 😕