If you’ve ever hesitated to eat broccoli, kale, or Brussels sprouts because you heard they “damage your thyroid,” or are “bad for Hashimoto’s” you’re not alone. This persistent nutrition myth has been around for decades, and it keeps many women from enjoying one of the most powerful food groups for hormone balance and long-term protection: cruciferous vegetables.
Let me the record straight.
Where the Myth Comes From
The thyroid produces hormones using iodine, an essential mineral found in foods like seafood, dairy, and iodized salt. In the 1950s and 1960s, studies on animals suggested that compounds in cruciferous vegetables called “glucosinolates” could interfere with iodine uptake in the thyroid.
When glucosinolates are broken down (especially from raw crucifers), they form substances known as goitrogens, which in high concentrations could contribute to goiter (thyroid enlargement) and hypothyroidism by inhibiting uptake of iodine.
This myth was further given traction when animal studies showed that cruciferous extracts led to goiter, but the amounts administered far exceeded what anyone would consume in a normal diet.
While some have touted case studies showing that consuming high amounts of crucifers can cause problems in humans and use it to justify limiting these foods, this observation in humans tends to happen when one is also consuming an iodine-depleted diet.
What the Research Really Says
So, in theory, thyroid problems could potentially happen only when raw crucifers are eaten in very large amounts in their raw form. Think mixing bowls filled with cups of raw kale, every single day, without cooking, steaming, or sautéing. A long-term vegan who loves Kale Caesar salad and eats it multiple times a day while avoiding iodine-rich seafood and dairy may end up with a problem.
Most people aren’t that person, and they aren’t interested in eating more than two pounds (1 kg) of raw broccoli daily. Plus, if you’re cooking your crucifers (which most people do), the enzyme that triggers goitrogen activity is largely deactivated.
So while this pervasive myth is not completely fabricated, there has to be a constellation of very specific circumstances to put oneself at risk.
Who Might Want to Be Cautious?
There are certain individuals who will want to be mindful. While the risk of problems is very low, risk increases in the following situations:
- a historically low-iodine diet. In the modern age, this is most someone who avoids seafood, dairy, eggs, and uses predominately natural sea salt in cooking. Table salt has had iodide added to it since the mid-20th century as a means of curbing goiter in the general population, and it worked like a charm! Some studies do suggest vegetarians are at higher risk of hypothyroidism due to low mineral intake needed by the thyroid, of which iodine is just one.
- an undying love of coleslaw or kale Caesar salad that you just can’t quit. Maybe you are the one-in-a-million who does eat a mixing bowl full of Kale Caesar most days of the week. Perhaps you’ve taken to green juicing and you love kale or broccoli or cabbage and are juicing them daily.
You’ll notice that I do not have anyone with existing thyroid disease is the ‘cautious’ category. I find the benefits of crucifers far too fantastic to recommend caution in this demographic, unless this person also comes with one of the circumstances I outlined above.
Why Crucifers Belong on Your Plate
The real risk is in avoiding crucifers, because this family of vegetables are among the most powerful health promoters we can consume, second only to (or perhaps even tying with) green vegetables. AND – joy of joys – some veggies are lucky enough to be both green and cruciferous! How lucky are we?
Cruciferous vegetables are essential power movers when it comes to detoxification, liver support, and cancer prevention. I’m totally unwilling to shun them based on the evidence that exists regarding thyroid concerns, and the large body of scienticic research supports their health benefits over any risk to thyroid.
Cruciferous vegetables:
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Are hormone helpers: they support estrogen metabolism and balance.
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Protect against cancers: they contain many unique phytonutrients that lower risk of various cancers.
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Promote Detox: AKA, your liver’s bestie – Crucifers support liver pathways that process environmental toxins.
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Are nutrient powerhouses: High in fiber, vitamin C, vitamin K, and loads of antioxidants.
The idea that they “damage the thyroid” is not only misleading, it’s harmful because it prevents women from reaping some of the best nutritional insurance nature offers.
The Takeaway:
Unless you’re eating buckets of coleslaw every day, crucifers are not a thyroid threat. They’re an essential food for hormone balance, disease prevention, and aging with resilience. So go ahead — roast those Brussels sprouts, toss kale into your soup, or mash cauliflower as a comfort-food swap! Add regular old table salt for extra iodine if you’re concerned about your portions.
Your thyroid will be just fine — and the rest of your body will thank you.
Want more practical strategies for hormone-friendly eating? Download my free guide: 5 Ways to 5 a Day and get quick, easy tips to balance your plate — starting with your very next meal.
Resources:
Shaikh A, Thomas R, Khan S. Estimation of Thiocyanate Content from Selected Cruciferous Vegetables. Biotech Res Asia 2023;20(4).
Babiker, A., Alawi, A., Atawi, M., & Alwan, A. (2020). The role of micronutrients in thyroid dysfunction.. Sudanese journal of paediatrics, 20 1, 13-19 .
Candussi, C.J., Bell, W., Thompson, A.S. et al. Risk of hypothyroidism in meat-eaters, fish-eaters, and vegetarians: a population-based prospective study. BMC Med 23, 269 (2025).
Prudencio-Brunello CM, Palencia RMD, Yangzom DK, Boddapati P, Nair A. Effects of a Vegetarian Diet on the Development of Thyroid Disorders. Cureus. 2024 Oct 13;16(10):e71360.
