Are These Vegetables Bad for Thyroid Health?

Are These Vegetables Bad for Thyroid Health?

Producer Potts  0:09  

Should we only be eating cooked veggies? Is there any truth yet to the idea that eating raw cruciferous veggies is bad for our thyroid health?

Dr. Sarah  0:18  

So the quick answer is no, both from a thyroid health perspective and cruciferous vegetables, as well as just from a general health perspective, with a few caveats for certain health conditions where cooked vegetables can be better tolerated than raw. So let’s tackle the cruciferous vegetables for thyroid health myth first, and then we’ll kind of expand out a layer and kind of talk about cooked versus raw vegetables more generally. So where that myth comes from is that the isothiocyanates in cruciferous vegetables are a product of like so the main class of phytonutrients in cruciferous vegetables are called glucosinolates. Glucosinolates live in a different cellular compartment from an enzyme called myrosinase. When we chew on the cruciferous vegetable, or we chop it up, we break those cell walls, and then those two components meet, and the enzyme myrosinase basically breaks down the glucosinolates into a whole new class of phytonutrients called isothiocyanates. There’s a few other thiocyanates, indoles, but isothiocyanates have been shown in petri dishes to be goitrogens, which means that there are compounds that interferes with thyroid hormone conversion from the pro thyroid, which is t4 to the active thyroid hormone, which is t3 so anything that interferes with thyroid hormone conversion from the prohormone to the active hormone, the pro hormone is a little bit active. It’s not exactly an inactive form, which is why we call it a prohormone. But anything that interferes with that conversion is called goitrogen. So isothiocyanates in petri dishes have been shown to be goitrogenic. There were a couple of studies done decades ago in like iodine deficient rabbits who were eating a ton of cabbage, and they developed goiters, which is a enlargement of the thyroid gland that is most more typically seen with iodine deficiency. So there’s this idea that in the context of iodine deficiency, maybe cruciferous vegetables can cause goiters and hypothyroidism, but there have been a collection of studies in humans eating either cruciferous vegetables, things like broccoli sprouts or rat sprouts, or taking supplements with these isolated compounds that have shown that when we were looking at the like, the full class of compounds, and how that’s like actually interacts with our entire biology, that there is no change in t3, t4 TSH, thyroid antibody numbers for people with autoimmune thyroid disease. So actually in humans, even in the context of iodine deficiency, and there’s some mechanistic studies, some animal studies in rats that have been done over the last five, six years that have been more thorough and more controlled than these original studies and rabbits that weren’t actually designed to test this, it was just kind of like a Oh, whoops. All of our rabbits have goiters. We think this might be it. So when they actually did experiments in rats, where they actually made this group iodine deficiency, and the iodine deficient in this group not, and then they gave this one a bunch of rutabaga sprouts, and this group not, and then they had all that, right, all of the different permutations of those conditions, they’ve been able to show in both these mechanistic studies that are really geared at sort of understanding all the like underlying biochemistry of what’s going on, as well as various human studies where they’ve looked at the viability of isothiocyanate as supplements. So for example, sulforaphane is a really famous member of this class of phytonutrients, and it’s famous because it pretty dramatically reduces risk of cancer, cardiovascular disease, as well as neurodegenerative disease like Alzheimer’s. So it’s a really important health benefiting phytonutrient. So if we can, if we don’t have to avoid it. We really shouldn’t be right, like it’s a very beneficial thing to have in our diets. So these more recent studies in humans, and then the more recent, much better controlled animal studies, have shown no change in thyroid function, even in the context of iodine deficiency. Very high intake of isothiocyanates from cruciferous vegetables. There was actually even one study in humans where it was not statistically significant, but as a statistical trend. So whether or not that would hold up in a larger study, we would have to do the larger study to know, but they actually showed a statistical trend towards the opposite, towards a reduced like basically, they’re looking at the people who qualified as having autoimmune thyroid disease at the beginning of the study versus people who qualified at the end of the study. Some people got a control and some people got an I isothiocyanate supplement. I can’t remember exactly what it was, and so they looked at how many people qualified as having autoimmune thyroid disease, because they had elevated thyroid antibodies at the end of the study. And there was a statistical trend. Again, physical trends always need to be followed up by larger studies, because we don’t know if it’s, if it’s real, or if it’s or if it’s not, and they but they showed a statistical trench towards a reduced incidence of new autoimmune thyroid disease in the people who are getting the high isothio isothiocyanates from cruciferous vegetables. So if anything cruciferous vegetables are doing the opposite, and are reducing the likelihood of developing autoimmune thyroid disease compared to the normal risk of that in the general population. Wow, more studies needed, but at the very least they show people with thyroid conditions or with a family history of hypothyroidism, don’t need to worry about cruciferous vegetables, and there’s so many health benefits to cruciferous vegetables. So the reason why the myth is it’s okay to have them cooked, but not raw, is because cooking deactivates the myrocyanines enzyme, so that if you if you cook the brussel sprout first and then chew it, it doesn’t matter that you’re making the glucosinolates and the myrosinase meet myrocynas is deactivated by the heat, so it can’t make the isothiocyanates. But here’s what’s really important to know, we have a bunch of gut bacteria that make myrocyannas, the enzyme that does the good stuff. So we still make isothiocyanates in our digestive tract. And the more you eat cruciferous vegetables, the more likely you are to have bacteria in your digestive tract that make myrocyanines. So we don’t have to only eat vegetables raw to benefit from isothiocyanates. We don’t need to worry, we’re still we don’t need to worry about only cooking them if we have autoimmune thyroid disease or any other type of thyroid disease. Again, your doctor does Trump me. So if your doctor has another reason for only wanting you to eat cooked Christopher’s vegetables, they, they they still know your health history better than I do, but I would maybe encourage you to bring some of these papers to them so they can see that maybe the science has changed since these rabbit studies from decades ago and and, but again, your doctor knows you better, Right? But yeah. So, like, we don’t need to only eat cruciferous vegetables raw to benefit from these compounds, and we don’t need to only eat them cooked if we have hyperthyroidism. So taking that, that step one level out, which is just talk about the benefits of this class, like not just sulforaphane but basically glucosinolates and their metabolites from when they meet myrocyanines, so isothiocyanates, thiocyanates and indoles as a class of phytonutrients. Their biggest protection for us is reducing the risk of cancer. They’re some of the most cancer protective phytonutrients that we can get. Kind of a their like competitor for anticancer benefits are the thiosulfinates in alliums, so the onion family. So they kind of work through similar mechanisms, but not identical. So it’s best if we eat both cruciferous vegetables, like broccoli, kale, cabbage, rutabaga, as well as onions, garlic chives, like ideally we’d get both. So those classes of phytonutrients very, very powerfully reduces risk of cancer. That doesn’t mean they prevent cancer completely. They just turn down our risk. And it doesn’t mean that they will cure cancer. This is about developing it. There is no diet that will cure cancer. So making sure we’re very, very clear whenever we say the C word, we want to make sure that we are very, very clear that we’re talking about reducing risk and not promising to eliminate risk or any kind of any kind of curative properties. But cruciferous vegetables are one of the most important vegetables to eat on a regular basis for reducing risk of cancer. So. And many, many different types of cancer are reduced by eating cruciferous vegetables regularly. They also reduce risk of cardiovascular disease, and as I mentioned, some of them, like sulforaphane, also reduce risk of neurodegenerative disease. Some of them are also really good for metabolic health, so it can also reduce risk of type two diabetes. So a very, very important class of phytonutrients. So taking that out yet another layer in our onion of raw, however you like vegetables, that’s the way to eat them, right? It’s much more important that you eat enough vegetables than whether or not they’re raw or cooked. Oh, that’s

Producer Potts  10:38  

good, okay, both,

Dr. Sarah  10:40  

If you like, both the changes in the fiber structure from cooking. When you take a raw vegetable and you cook it, however you cook it, heat is what causes the changes. So it doesn’t matter if you steam it or boil it or roast it or saute it or stir fry it or grill it, right however you cook it, the changes that that heat causes in the fiber structure change what species of bacteria will eat that fiber. It basically changes the food so that it will support different species of bacteria, still good species. So we’ve got great, good, desirable gut bacteria that like to eat the fiber from raw vegetables, and we’ve got other good, desirable gut bacteria that like to eat the fiber from cooked vegetables. So in an ideal world, because dietary diversity helps to support gut microbiome diversity, this also refers to diversity in preparation methods for at least fruits and vegetables. So ideally, we would mix it up and sometimes eat our vegetables cooked and sometimes eat our vegetables raw. So ideally, we’d be consuming both. Studies that have looked at how raw versus cooked vegetables impact all cause mortality, which is a general indicator of health and longevity, show that they’re independently beneficial, again, meaning we are healthiest when we consume both, when we incorporate both raw and cooked vegetables into our overall diets, and they both reduce risk of all cause mortality by about 10% per 100 grams we consume per day. So kind of a similar magnitude of benefit. So ideally, we would have raw and cooked vegetables every day, or at least most days mixing it up. But again, that is like, secondary to getting enough vegetables. So if you only like your vegetables roasted that’s the only way you’re going to eat vegetables. It’s much better to eat those roasted vegetables than to try to, like, choke back the carrot sticks that you hate, right? If you only like salad and you don’t like roasted vegetables, it’s much better to eat that salad rather than to, like, gag on the roasted vegetables, right? So it’s, you eat enough vegetables, but like the next, the next level of iterating on, if we’ll call it, an optimal human diet, although I’m not sure such a thing truly exists. But the next level of iteration would be to mix up raw versus cooked, in addition to mixing up full eat the rainbow and the different fruit and vegetable families, and, you know, also hitting dietary diversity and your 30 plant foods a week, like, among all of that, like next level stuff, would be mixing up raw versus cooked, because they’re independently beneficial.

Producer Potts  13:18  

This is so incredibly helpful. Thank you for busting that myth and then also just making us realize we don’t have to fuss as much as we think we do like it’s just about enjoying them how we like them. And if that’s a mix, that’s great and if not, no big deal. So where can we learn more about myth busting like this? This was fascinating, so we

Dr. Sarah  13:40  

are adding a lot more myth busting articles to nutrivore.com and there is an entire chapter busting myths like this, including talking about isothiocyanates as goitrogens in my book nutrivore. So chapter 10 is entirely dedicated to busting myths that make you afraid of food. So I would like to alleviate your fear of especially health promoting foods that are easy to prepare, accessible, found in most grocery stores, and budget friendly. I want to make sure that I am giving you good information about those foods to counteract all of the fear mongering misinformation that’s online about those foods. So that’s why there’s an entire chapter of my book dedicated to myth busting. So I would say, come check out the website, youtuber.com or pick up a copy of my book. Also, you can request a copy of your local library if your library doesn’t have a copy already. And also, like, stick around, because we like to bust myths on social media. So probably, if there’s a myth you’ve heard, it’s probably on my video To Do List, too.