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Iodine deficiency 'may lower UK children's IQ'

Iodine deficiency 'may lower UK children's IQ'

Imagine my shock, not at the science/medicine/health, not only that it was in the media, but that it was even on the headlines of the Today program on Radio 4!

Seems there is a Lancet article.

2 May 2013 Last updated at 07:53

Iodine deficiency 'may lower UK children's IQ'

By James Gallagher Health and science reporter, BBC News

Mild iodine deficiency during pregnancy could be dimming the intellect of some babies born in the UK, say researchers.

Their study of 1,000 families, published in the Lancet, showed lower IQs and reading scores in primary school pupils whose mother had had too little iodine while pregnant.

Academics advise women of child-bearing age to maintain iodine in their diets by eating dairy products and fish.

Women were warned not to take seaweed pills, as they contain too much iodine.

Iodine is essential for the development of the brain as it is needed to build some of the body's hormones. A severe deficiency is the leading cause of preventable brain damage in the world.

It was mainly thought of as a problem in developing countries, yet previous studies have also suggested that some women in the UK are mildly deficient. The impact of low-level deficiency was, however, previously unknown.


Researchers at Surrey and Bristol Universities looked at iodine levels in urine samples taken from pregnant women in south-west England.

"It's very well known that iodine deficiency can lead to impaired brain development in areas of severe iodine deficiency," the lead researcher told BBC Radio 4's Today programme.

Prof Margaret Rayman said: "What's novel about our study is that we've carried this out in an area where the deficiency is much less."

The study showed that iodine deficiency was common - affecting two-thirds of women.

Their children went on to have slightly lower IQs at the age of eight and worse reading ability aged nine.

Dr Sarah Bath told the BBC: "We saw a three-point IQ difference between children who were born to mothers with low iodine in early pregnancy and children who were born to mothers above the cut-off."

The researchers said this "may prevent a child reaching their full potential" and was an "important public health issue".

Their advice, published on the British Dietetic Association website, recommends that pregnant and breastfeeding women need 250 micrograms per day and other adults need 150mcg.

<Table of Iodine Content omitted because it would be unreadable - see and follow link at end>

Prof Rayman said: "Our advice is to make sure they have enough iodine intake, and take additional iodine in safely, probably from food - dairy products, fish."

But she pointed out that iodine levels in organic milk are 42% lower than in regular milk, adding that if pregnant women are drinking organic milk, "they need to drink more of it".

Dr Bath warned against using kelp or seaweed supplements, as they are packed with so much iodine it could cause problems.

A large number of pregnancies are unplanned, so the advice is to all women of child-bearing age.


It had been thought that the UK had dealt with its iodine problem decades ago by "lucky accident". Changes to dairy farming meant cows' milk contained more iodine and at the same time the government was encouraging people to drink more milk.

Other countries - including the US, Denmark and the Netherlands - added iodine to salt so that bread and processed foods became a major source of iodine.

However, the researchers argue it is too soon for the UK to consider a similar measure, as iodine deficiency across the country has yet to be assessed.

Dr Mark Vanderpump, a consultant physician at the Royal Free Hampstead NHS Trust, argues in favour of adding iodine to salt.

However, he said this would provoke fierce debate similar to arguments about adding fluoride to water in order to protect teeth.

In the meantime, he warned pregnant women against suddenly starting to take supplements.

"If you take a supplement during pregnancy, the thyroid gets stunned and goes down. Taking a supplement during pregnancy may not be the best thing to do."

A Department of Health representative said a healthy balanced diet should be enough for women but: "We keep track of emerging research, such as today's report.

"The Scientific Advisory Committee on Nutrition is currently considering the issue of iodine deficiency in the UK. There are currently no plans for fortification of salt with iodine."

They specifically said that seaweed products have TOO MUCH IODINE and could be problematic.


15 Replies

Its also in the papers today as Chris Evans was reading it out on Radio 2.

Moggie x


I heard this and the piece about Vit C on Radio 4 too.

I recall being told when pregnant with my first child ( who is now 40) that it was important to ensure a good intake of iodine, and to eat fish and seafood, both of which I love so it was no problem for me. I also seem to recall that many years ago they used to add iodine to salt, I'm sure it used to be on the labels, but it hasn't been added routinely for a very long time. Funny how things come full circle!!

In the supermarket whose name sounds like 'leeeeetle' - not sure if we can say real shop names - they sell packets of salt which clearly state they contain iodine.

It makes you wonder if the current dietary advice about reducing salt has thrown the baby out with the bath water.

As my granny used to say 'a little of what you fancy does you good' and 'all things in moderation'.


There is no problem honestly mentioning shops and products.

Lidl do indeed always stock iodised salt. Several other supermarkets also do so - maybe not in all branches, maybe not all of them.

Some processed foods, especially those sourced from Germany, are made with iodised salt. Classic examples are some stock cubes.

I do not believe that iodised salt was ever that common in the UK - though certainly Cerebos brand has long been an option.

What I have never seen is a product similar to Lo-Salt (i.e. a low sodium form of salt) which is also iodised.



There was an article about this in the Daily Mail today. Absolutely no mention that low iodine levels give you hypothyroidism as the theyroid has no raw materials to work with..... and it is this that causes cretinism. And absolutely no mention of the fact that the UK is iodine deficient in the soil..... this was announced a couple of years ago in a press release by the society for endocrinolgy.



Yes I heard about this on the BBC morning show - they did mention that it could cause thyroid issues in the last sentence of the report but that was it.


As pregnancy seems to be the start of thyroid problems for so many women does this show us anything? Not making myself very clear here. I became overactive after my son was born, graves disease. I are a very healthy diet, plenty of the right foods full of iodine, folic acid etc. We had been told we could not have children so pregnancy at 41 and I was doing it right!! My son is extremely smart, no honestly, not just a proud mum i obviously did well with my iodine intake but did I have too much resulting in my condition? I know that it is not as simple as that but is there a link as lots of women are hypo after pregnancy, is it possible our intake of iodine starts us down the road to thyroid problems? Anne F


The whole iodine issue is going to remain difficult until both the science is better understood and the clinical aspects addressed. As I have repeatedly said here, lack of any real urinary iodine testing regime in the UK, we really don't know where we are. Neither individually nor as a community.

(Some other less awkward and, hopefully, less expensive test would be good, that at least is a realistic possibility but I do not know of any.)



I take BioCare TH207 Thyroid health complex, with Dulce seaweed. The daily dose of 2 capsules - and I only take 1 - provides 140 mcg of elemental iodine, which is not above the daily recommended dose. I think it is important to supplement or complement iodine with selenium and I have been told by the endo to take 100 mcg of selenium daily if 'I want my thyroid to live longer'.


Are you on any thyroid hormone supplementation at all (levothyroxine, liothyronine or desiccated thyroid)?

If so, have you factored the iodine content of that into your daily intake?

Plus whatever is present in your diet.

I am not saying that you are taking the huge sort of dose some say they do. Simply that it is so very, very easy to get it wrong for one reason or another. At the end of the line, it would be wonderful if we could, for next to no cost or inconvenience, actually measure our iodine levels accurately enough to know whether we need to supplement at all, and by how much. (That is, able to do it regularly enough to closely monitor.)



Thank you for this, Rod. I am not currently on any medication and only take 1 capsule to allow for anything I eat/drink. Should I be started on any medication I would alter or discontinue iodine intake but it is indeed always trial and error with what we take.


I have read that Selenium helps with utilisation of Iodine and if more Iodine than needed is taken down-regulates its action/absorption.

NB This advice also said that natural Se [as in 2 Brazil nuts] works for this event -rather than pharma mineral version found in muli- vits.


One point that I do not see mentioned in any of the postings and may be of interest to forum members is the fact that during the discussion with Prof Rayman on the Today programme, she was questioned about the organic milk issue and the fact that it contained less iodine.

The interviewer asked if pregnant women should avoid organic milk and she replied that they would need to drink more in order to obtain the necessary amounts.

She went on to explain that the cows diet contained clover which is goitergenic and this prevents the uptake of iodine by the thyroid.

I haven’t seen this explanation mentioned again in any of the articles elsewhere and I don’t know if a pregnant women with an existing thyroid condition should avoid organic milk, it would be useful to know.


That is very interesting and a quick google around found several sites (including several academic sites) which appear to back up that idea/theory.

So what is the effect on organic cows in other ways? Are they all hypothyroid? Do calves of organic cows tend to have a lower IQ?

The ripples from this sort of issue have a tendency to ripple ever outwards.



That's an interesting thought, I don't know anything about cow's physiology but there are papers on pub-med concerning thyroid gland activity in cattle.

I shall resist the urge to start reading these, I have enough trouble trying to work out my own thyroid function.

I did find the link to the University of Surrey who carried out the research;

and the link for the factsheet on the subject;

The other issue on the Today programme concerned the advice for pregnant women to eat more fish in order to increase their iodine intake.

I seem to remember that government advice was to limit this to two portions a week as some fish may contain high levels of mercury. The interviewer did question the advice given and the response was that organic fish shoud be consumed. There is no mention of this in the factsheet, even though mercury may harm an unborn baby's developing nervous system.

It does seem irresponsible to distribute this advice when it's incomplete - Maddie


It is a total nightmare trying to do the right thing!

I guess farmed fish don't get fed clover? :-) :-) :-)

But there have been many questions over the use of various pesticides in fish farming and mercury is usually highest in wild fish, is it not?

Yes - fish do have thyroids!



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