Latest / Common Sense Health / Iodine Deficiency: Are You Getting Enough?
Transcript
- Stephen: Hello, iodine! It's the 53rd element on the periodic table. It's the 60th most abundant element on earth. And it's one of those things that sounds like it belongs in a locked medicine cabinet. Yet we mostly meet it through the salt shaker. By the way, researching this has genuinely made me buy some iodized salt. Because iodine is one of those things that can be a tiny input, big consequence nutrient. You don't need much, but you definitely need it. It's also got a couple of party tricks. If you drop iodine onto starch, it turns black or blue straight away. So you could drop it onto bread. ⁓ Paper works too because paper contains about 5 % starch, which is why iodine ends up in those pens used to check your bank notes. Remember bank notes? Anyway, pure iodine is reactive and in the wrong amount poisonous. So it's often diluted like a 2 % antiseptic solution or it shows up as iodide, which is iodine with an extra electron. It's been used for disinfecting skin and even for water in emergencies. You can put five drops of iodine in about a litre of water and within 30 minutes it's safe to drink. But why do we eat it? Well, because the thyroid is obsessed with iodine. The thyroid makes hormones called T3 and T4 and those numbers are literally the number of iodine atoms in each hormone. If you don't have enough iodine, you can't make enough thyroid hormone. Pretty simple really. And when you can't make enough thyroid hormone, the pituitary gland responds by pushing out more TSH, thyroid stimulating hormone. And the thyroid can enlarge as it tries harder to trap iodine from the bloodstream. And that enlargement is a guetta, the visible lump that you get on the neck. And historically they could get really big, mean up to the size of a watermelon. Now, iodine was discovered in 1811 by a French chemist called Bernard Courtois, who was using seaweed to manufacture a saltpeter for gunpowder. in Napoleonic era, so demand was pretty high for gunpowder. Courtois cleaned his seaweed containers with sulfuric acid, added too much one day and purple fumes rose up and condensed into dark crystals. Voila, a new element discovered. It was named after the ancient Greek for violet colour, Ioedes. I'm sure that is not how you say it, but ⁓ I did try to pronounce it with confidence there. not long after this 1811 incident, doctors noticed iodine could treat Goethe's, the Swiss doctor Jean-Francois Coignet worked out that iodine was probably the active ingredient in the old remedy involving burnt sea sponges. And he gave diluted iodine solutions to patients and Goethe's could vanish as fast as eight days in. So that's when it became clear the neck lump wasn't just the full story. It was the bit you could see. And there were some other serious issues as well. Early fetal development relies on thyroid hormone from the mother. Some fetuses don't have an active thyroid until about halfway through pregnancy. severe iodine deficiency in the mother in that context can lead to and this is an outdated and pejorative term Cretinism right historically involving physical stunting muteness deafness and sadly as that awful term implies intellectual disability so Goethe's were the obvious sign, but the bigger cost was often hidden now Here's the environmental twist iodine cycles from the ocean to the air to rain to the soil and then into the food but inland areas can be iodine poor and the places hardest often had glazier ⁓ Damn it. the Ice Age, glaciers scraped away soil layers hundreds of meters deep and stripped them of nutrients. And that's one of the reasons places like Switzerland and the American Midwest had such a strong pattern of iodine deficiency. So, yes, glaciers did a lot more than just give us these scenic valleys. They also bulldozed the pantry. Now, Switzerland became famous for goiters. Mark Twain himself visited and wrote back that he'd seen Mont Blanc and the Goite. So now I'm coming home. Now, in some remote Swiss areas, 94 % of men had goiters and as many as 10 % of babies showed signs of cretinism. The question was what to do about it at scale without dosing people like a chemistry experiment. So a Swiss doctor called Henrik Hunsiker proposed a simple idea. The environment drives iodine deficiency and the thyroid enlarges to compensate. So add iodine back into the diet. The worry was about safety and dosing. So the elegant answer was salt. It's cheap, it's stable, it's widely available and people eat it in small amounts. And then came the best piece of practical medicine I've heard about recently. In the winter of 1918, a physician called Otto Bayard went to Goiter-affected village and used a snow shovel to mix potassium iodide into salt for five families. The train line was then closed for winter so there was no quick undo button. But when he returned in spring, harm had been done and everyone's goiters were gone. So then he expanded it to over a thousand people for six months and got the same results. So by the early 1920s, Switzerland was implementing iodized salt nationally and within a few years, goiters had largely disappeared. Now the US had its own version of this, particularly in the so-called goiter belt in northern Michigan in 1917. More than 20,000 men were ineligible for military service because of goiters, the biggest reason for medical disqualification in that area. School surveys found goiter rates of 70 to 100 percent in children. So a doctor called Dr. David Cowey pushed iodized salt hard, giving nearly 200 lectures. in 1924, local producers rolled out iodized salt. And within months, it was 90 percent of salt sales in Michigan. So in Michigan, iodized salt stayed around 90 to 95 percent of sales. And within 10 years, less than two percent of children in the Detroit area had goiters down from over 90 percent. So Switzerland saw those other knock on benefits as well. The national rate of deaf mute births fell from one in six hundred to one in three thousand matching worldwide levels for the first time. And since 1930, there had been zero documented cases of a Swiss child born with cretinism. So globally, almost 90 percent of the world now has access to iodized salt. And this has prevented an estimate of 720 million iodine deficiency disorders in the past 30 years. But it's not finished work. There's still about a billion people that still don't have access to iodine. Over 200 million still have goiters and an estimated 5 million babies are still born each year with iodine deficiency disorders. So now let's go to the practical bit. How much do we actually need? Now the baseline recommendation intake is at least 150 micrograms per day. And women planning pregnancy or who are pregnant or even to the point now where they're breastfeeding are advised to take a daily supplement containing at least 150 micrograms of iodine. In the U.S. iodine salt is made by adding potassium iodide in water about 0.01 percent and it's calibrated on the assumption that If have about a teaspoon of salt per day, you'll land around the intended iodine target. You can consume too much iodine, but on a normal diet that's pretty difficult. You'll usually hit your salt limit first. So where do you find iodine in food? Well, here's the reality check given as micrograms of iodine per 100 grams of food. Now most plants, many fruits, veg and grains, they sit around one to three micrograms. Most meat is under five micrograms. Fish is not reliable because some saltwater whitefish and shellfish have a lot of iodine, others don't have even a tenth of that. The real standouts are seaweed at 2100 micrograms per 100 grams and iodized salt at around 5200 micrograms per 100 grams. Which is why the just eat vegetables and you'll be fine advice is comforting, but not mathematically persuasive. Then there's the curvable, dairy. Now nearly half of iodine intake in the US is thought to come from dairy. Part of that may be iodine added to cattle feed, but there's a very plausible second factor. Iodine is used as an antiseptic to clean cows and milk in equipment, and some ends up in the milk. It's not the perfect system to rely on, by the way, but the story does fit the evidence. Australia, for instance, they've got a cautionary tale because once the iodine containing dairy sanitizers were removed over contamination concerns, the country became iodine deficient. Pretty much overnight actually. So one more point on testing ⁓ about iodine. You'll often hear that iodine is hard to assess because intake fluctuates and single measurements can be noisy. Well, that said, it's simply not correct to imply you can't test an individual at all. You can assess iodine status using an iodine clearance test. It's a test where you're given a set dose of iodine and over the next 24 hours your urine is collected to see how much you have excreted. If you are deficient in iodine your body will hold on to it and very little if any will show up in the urine. Simple really. The amount of iodine in the urine will provide a good guide to supplement requirements if there are any. It's very straightforward. And where I've landed is really simple. I'm not binning my kosher salt, my Celtic salt or my Malden sea salt because I'm still human and I like it on my food and it does taste great. But I have added a small shaker of iodized salt to the mix and I'll use a bit of it across the week as a little bit of a hedge. It's not a dramatic lifestyle change. It's just one of those small sensible adjustments that prevents you from rediscovering an old problem the hard way. Now, ⁓ If you've enjoyed this sort of practical, easy to understand content and you want more of it, come and join my online community using the link in the description to this video or use the QR code which is on the screen. Anyway, I to thank you for watching. If you've got to the end, I do hope you enjoyed it. And if you did, please consider liking, sharing and subscribing. Add a comment if you want. If you got to the end and you didn't really like it or you thought it was a bit too wishy washy for you, then put a comment to that effect and I'll try and do better on the next video. Anyway, I want to thank you for watching and I hope to see you on the next one.