The silent deficiency that is ravaging the ‘healthiest’ – leading to osteoporosis, muscle wasting and wreaking havoc with women’s thyroids. But a simple step could reverse the damage

What do a pregnant woman in her 20s and a woman in her 70s who drinks oat milk have in common? It’s not obvious but they may both be worryingly low in iodine.

For the younger woman this could lower her unborn baby’s IQ, while the older woman is putting herself at risk of osteoporosis, confusion and a stroke.

Iodine is a simple mineral needed to make thyroid hormones, which help control metabolism, growth and brain development. And in the UK too many of us aren’t getting enough – as highlighted last week during International Thyroid Awareness Week.

Yes, another health awareness week. But the two women I’ve described exemplify why this one really matters.

The pregnant woman thinks she’s doing everything right for her baby. She stopped drinking, gave up smoking, cut caffeine and is taking the NHS Healthy Start women’s vitamins (given to those who are pregnant or breastfeeding).

But while she might assume, perfectly reasonably, that these supplements contain the nutrients she and her baby need, she is wrong.

They do not contain iodine. And this matters profoundly.

A developing baby depends on thyroid hormones for brain development. Studies have linked inadequate iodine in pregnancy with lower verbal IQ and poorer reading scores in children – in other words, their intellectual capabilities have been reduced due to a mineral deficiency.

And, worryingly, a new review in the journal Clinical Endocrinology reports that iodine deficiency has quietly re-emerged in the UK, especially among women of reproductive age and those avoiding dairy.

Britons used to get iodine almost by accident.

Milk became one of our main sources, partly because iodine was used in cattle feed (to prevent deficiency in dairy herds, which meant healthier cattle) and partly because of iodine-based disinfectants in dairies.

We did not solve iodine deficiency through a brilliant national strategy. We stumbled into protection through the milk supply.

But diets changed; milk consumption fell as more people moved away from dairy because of changing taste, concerns about lactose intolerance, vegan diets and worries about saturated fat.

Meanwhile, fish and egg (the other main sources of iodine) consumption remained low. As more people avoided dairy, oat milk, almond milk and soya milk became a normal part of our national diet.

There is nothing wrong with choosing a plant-based milk. But while a glass of cow’s milk can provide around 60mcg of iodine, an unfortified plant-based alternative may provide around 2mcg.

Indeed, only 28 per cent of milk alternatives – and just 6 per cent of yoghurt alternatives – are fortified with iodine, according to the new review, which was led by Dr Peter Taylor, an associate professor in diabetes and endocrinology at the University of Birmingham and a world-leading authority on medical problems associated with iodine.

Iodine is awkward to measure: most of the iodine we eat is quickly passed out in urine.

But even urine levels aren’t very useful, because your urine iodine can swing up and down depending on what you ate the day before – if you had a glass of milk, eggs and fish your iodine level may look fine, but if you didn’t, it may look low.

However, if you test enough people, the average urinary iodine level gives a good picture of whether a population is getting enough. And the picture in Britain is not good.

The World Health Organisation considers a urinary iodine level of at least 100mcg per litre is adequate in non-pregnant adults. In pregnant women, the level should be at least 150.

But the latest UK figures show that in women aged 16 to 49, the average level was just 82mcg per litre. In plain English, the very group who can become pregnant and need more iodine are most likely not getting enough in the first place.

Levels have also fallen substantially in teenage girls and adults. Among girls aged 11 to 18, it’s fallen by 29 per cent since 2013, and is now 95mcg per litre; in adults aged 19 to 64, it’s fallen by 25 per cent and is now 89mcg. This is an unacceptable and dangerous national nutritional gap.

Dr Taylor told me many people assume iodine deficiency is a problem of the past.

‘The crazy thing is that the NHS Healthy Start vitamins contain folic acid, vitamin C and vitamin D – but they do not contain iodine. However commercial tablets such as Pregnacare, for example, contain 150mcg iodine. Excellent pregnancy care should be for all, not just those who are knowledgeable enough and rich enough to buy the right pregnancy support vitamins.’

Pregnancy is not the only issue. Take the older woman I described at the start: she’s read all the advice about dairy and saturated fat and cholesterol, and – wanting to be healthier – has swapped her daily glass of cow’s milk for oat milk.

But because most plant milks don’t contain iodine, over time she’s at risk of thyroid hormone problems.

Long-standing iodine deficiency can make the thyroid work harder. This can lead to thyroid enlargement, nodules and multinodular goitre (an enlarged, lumpy thyroid). In older people, nodules can start producing excess thyroid hormone, resulting in an overactive thyroid. This is not a minor inconvenience: it can contribute to atrial fibrillation, an irregular heartbeat which can lead to heart failure and stroke.

It can also lead to osteoporosis and muscle wasting because thyroid hormones help control the speed at which our cells work, including the heart, bones and muscles, with knock-on effects such as frailty and falls.

As an A&E doctor, I see the consequences of these problems all the time. Many of these could have been prevented if more people had been getting enough iodine every day.

But panic-buying iodine tablets is not the answer. Nor are the social media ‘thyroid detoxes’, ‘iodine resets’ and seaweed drinks, which can have wildly unpredictable and sometimes enormous amounts of iodine.

The thyroid is a Goldilocks organ. Too little iodine can cause problems; too much can also disrupt function, especially in people with underlying thyroid disease. The recommended daily iodine intake for UK adults is 140mcg.

If you’re vegan, dairy-free or do not eat fish, look for iodine-fortified foods or consider a supplement containing around 150mcg iodine – in the form of potassium iodide (as recommended in Dr Taylor’s review).

But putting it on to individuals to ensure they’re getting enough iodine is not enough, it is a public health failure dressed up as personal responsibility.

We need a national iodine strategy that finally catches up with how people actually eat and drink in the year 2026, not 1976.

NHS pregnancy vitamins should contain iodine. Plant-based milk alternatives should be fortified.

And we need a serious discussion about fortifying salt with iodine. The UK is unusual among high-income countries in not doing this. Yes, we’re trying to reduce salt intake because too much raises blood pressure. But where salt is already used in food production, particularly in bread, it could be iodised.

The sad irony is that we’re investing billions in artificial intelligence while failing to protect natural intelligence with one of the cheapest public health measures available.

My advice to overweight drinkers 

Another remarkable finding about the new weight-loss injections is that they may not just reduce appetite for food, but also cut the desire to drink alcohol.

This matters because being overweight and drinking too much is a dreadful combination for long-term health.

Both raise the risk of high blood pressure, fatty liver disease, heart disease, poor sleep, depression and some cancers. Together, the risks are even higher.

A new study, published in The Lancet, showed that when adults living with obesity and who drank significantly (about 60 units a week, around three to four pints a day) were given semaglutide (the drug in Ozempic and Wegovy), after 26 weeks they had fewer heavy drinking days than those on a placebo. They also drank less alcohol overall and reported less craving for booze.

(And this wasn’t just based on what people said; blood markers linked to alcohol use also improved.)

If you are overweight and drink too much alcohol, my firm view now is that you should use obesity injections.

Follow Professor Rob Galloway at @drrobgalloway