Whole foods

Goitrogens and Your Thyroid

September 12, 2023

Should you be worried? Can veggies be bad for you? A sensible approach to dietary goitrogens.

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I'm a Nutritionist, Metabolic Balance coach, foodie, Mamma & Hashimoto's thriver. A few years ago Hashi's was kicking my in the butt. Now I help other women to regain their energy & maintain a healthy weight with ease. 


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Heard that you shouldn’t be eating things like cabbage, broccoli or spinach because they are bad for your thyroid?

If some people are to be believed then those with Hashi’s should cut out grains, nightshades, soy, eggs, nuts, seeds, dairy, chocolate, sugar, alcohol and a decent percentage of vegetables that are considered goitrogenic like broccoli, cauliflower, kale, spinach, cabbages, bok choy, turnips, radishes, almonds and fruits like strawberries, peaches, cherries, plums, apricots the list goes on.

Personally, I hate kale so I’m happy to have an excuse not to eat that one but everything else? What’s left?! And surely broccoli as the beloved staple of most Australian homes is worthy of its place on our dinner plates. We’ve all been brought up with the knowledge that broccoli is a super healthy food. I’m sure you’ll agree it is worth looking into this further.

So, what actually are goitrogens?

Goitrogens are natural compounds found in certain foods that can potentially interfere with the normal function of the thyroid gland. They are named after “goiter,” a term used to describe an enlarged thyroid gland. Goitrogens aren’t necessarily unhealthy, antioxidant flavonoids also have goitrogenic potential. Goitrogens work by disrupting the thyroid’s ability to produce hormones, primarily by interfering with iodine uptake but some do affect the thyroid via other mechanisms. And if you’ve ever looked into thyroid health you’ll know that iodine is a rather important mineral. It’s an essential ingredient for your thyroid to manufacture hormones. It’s like basil to tomatoes, Sam to Frodo or big hair to The Bee Gees.

Interesting Fact; a goiter forms as the thyroid tissue becomes enlarged to try and capture more iodine so it can perform its hormone production responsibilities. Iodine deficiency is the most common cause of goiters.

But as goitrogen describes anything that has the potential to cause goiters or thyroid enlargement by interfering with iodine uptake, here are a few non-food examples too; cigarettes, fluoride, pesticides, nitrates, regular exposure to swimming pools & spas, lithium and other medications, Perchlorates (found in munitions, fire works, matches), chlorine, bromines, endocrine disrupters such as BPA, parabens, phthalates and other industrial chemicals and environmental pollutants.

So as you can see it’s not just food that can be problematic. In some circumstances the exposure to these goitrogens can be much higher than exposure through food and are therefore potentially far more concerning.

I’ve got something that might blow your mind too, too much iodine can also be goitrogenic! This is why I don’t recommend high iodine doses and why it’s essential you seek testing and professional guidance prior to supplementation. It can actually make things much worse as I discovered when I was administered an iodine based contrast dye as part of a medical imaging test a couple of years before I was diagnosed with Hashimoto’s disease.

FYI Iodine deficiency is the most common cause of hypothyroidism in developing countries where dietary iodine intake is lower. In the West the most common cause of hypothyroidism is autoimmunity AKA Hashimoto’s thyroiditis.

Should goitrogenic vegetables be avoided?

In short, no. I advocate for a more sensible approach where we don’t need to fear healthy whole foods. While there are many goitrogens, whole foods sources are the least of concern and offer many health benefits with regular consumption. But I do have some guidelines to ensure they aren’t a problem.

  • Cook or ferment goitrogenic vegetables to reduce the goitrogens by about 30%. Boiling them for 30 minutes reduces the goitrogens by 90% but you’ll also lose a lot of other nutrients and it will be a mushy and tasteless mess. I recommend steaming goitrogenic vegetables to al dente or stir frying them. This does mean that having slaw every night for dinner or a spinach & kale smoothie for breakfast every day may be too much for you. You can steam kale and spinach and then freeze for smoothie or find alternatives. I still eat slaw but only once a fortnight or so.
  • Variety is key! If you eat a broad variety of plant foods then you’ll never be in danger of over consuming one type of food. Almonds and some fruits are goitrogenic but if you make sure you have a variety of nuts & fruit then you will be reducing your overall load of goitrogens. So if your dinner staples are always broccoli, carrots & peas, it’s time to get creative and shake up your dinner routine.
  • Get your iodine levels checked, if you are deficient then it needs to be addressed so that the dose of goitrogens found in vegetables isn’t problematic for you. And if you start supplementing, get it retested every 3 months so you don’t accidentally get into iodine excess.
  • Meal plan iodine rich foods into your week like seaweed varieties, fish, shellfish, eggs and sea salt. I don’t recommend iodised salt because it can lead to iodine excess which is just as problematic. Iodine is the biggest balancing act in the thyroid world and you want to get it right. Don’t DIY it with supplements which is essentially what salt fortified with iodine is. Sea salt will naturally contain some iodine as it comes from the ocean so look for a good quality sea salt instead of table salt which is bereft of naturally occurring minerals due to how it is processed.

What about soy?

Soy is a bit of a special case as so many Hashimoto’s sufferers are intolerant to it. Gluten, dairy, soy and corn are the worst food intolerance offenders I see in clinic (in that order). So I would trial eliminating it for two weeks and then challenging it back into your diet to see how your body responds first. If you think you tolerate it then again, make sure it is cooked or fermented (tempeh anyone?) and don’t over consume it. It’s also a food that is higher in pesticides and GMO so select high quality soy products that are organic and GMO free. Again, make sure your iodine levels are adequate.

So unless you need an excuse not to eat kale at a dinner party – so sorryyy, I can’t eat kale it’s goitrogenic – you should not worry about avoiding goitrogenic foods.

The bottom line is not to fear any vegetables or whole foods unless you’ve established that you are intolerant to them but also, keep an eye on those iodine levels. Make them part of your annual thyroid check up, it’s too important to ignore.

Enjoy your broccoli!

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