One of the first things you’ll find when you Google “thyroid” and “diet” is advice telling you to stop eating broccoli and it’s cousins in the Brassica family including cauliflower, bok choy, cabbage, kale, brussel sprouts, etc.
But, not only are these veggies pretty delicious, you’ve heard that they also metabolize estrogen and fight cancer—so what’s a hypothyroid girl to do?
While there are several causes for hypothyroidism, it is estimated that nearly 90% is due to an autoimmune attack on the thyroid gland known as Hashimoto’s1.
Hashimoto's diagnosis is on the rise and is considered the most prevalent autoimmune disorder in the US2. Scientists estimate that 7–8% of the US population have antibodies against their thyroid1, and these have been shown to be markers for future thyroid disease3. Due to the prevalence of Hashimoto's, thyroid-specific nutrition advice should focus on quieting this immune attack, and eschewing broccoli doesn’t do a thing for that.
So what gives? Is the "broccoli is bad" advice an urban myth? No, it’s not based in mythology, but it’s also not a meaningful way to impact your thyroid condition.
The reason broccoli, and other Brassica veggies, make the thyroid no-no list is because they contain compounds called goitrogens, which can affect the thyroid’s ability to do its job. Soy is also a goitrogen and makes the thyroid naughty list as well.
A goitrogen is simply a drug, chemical, or food compound that disrupts the normal production of thyroid hormone by blocking the thyroid gland from taking in iodine. The hormones your thyroid makes are made up of the amino acid tyrosine and three or four molecules of iodine (hence the thyroid hormone names of T3 and T4).
If this iodine-blocking process is going on in your thyroid, it will begin to swell, causing a non-toxic goiter (an enlarged thyroid gland that is swollen but not overproducing hormones).
This swelling from too many goitrogenic foods then blocking iodine uptake happens as the pituitary bombards the thyroid with TSH (Thyroid Stimulating Hormone). It does this in attempt to get the thyroid gland to kick out more thyroid hormones.
What you’ll see in your blood work is high TSH and low thyroid hormones, T3 and T4.
Here’s the kicker: if Brassica veggies or soy are the cause of hypothyroidism, simply taking those foods out would “fix” it. You’d feel better and your labs would return to normal.
However, the main cause of hypothyroidism in the Western world is not goitrogens but rather an immune system attack (Hashimoto’s) on the thyroid gland. Over time this attack destroys tissue, and there’s less healthy thyroid available to make hormones, creating hypothyroidism—but not because of low iodine intake.
It’s important to know why you have hypothyroidism. If it is Hashimoto’s, skipping Brassica veggies can cause you to miss out on some great cancer-fighting, estrogen-metabolizing, liver-supporting, high-fiber power foods, and do little to improve your thyroid health. Besides, most of us couldn’t possibly eat enough broccoli to induce thyroid problems anyway.
Soy, on the other hand, could possibly cause thyroid problems because it's so ubiquitous in our modern diet. If you have a soy latte with your high protein soy cereal covered in soy milk for breakfast, some tofu for lunch, a soy protein bar for a snack, and some more tofu at dinner, then you could possibly induce a goiter.
Long story short: it’s unlikely that Brassica veggies are significantly hindering your thyroid. And if you have Hashimoto’s, getting that immune system under control is job one—not curtailing your cauliflower intake.
However, cooking does destroy most of the goitrogens in these foods, so more cooked vs. raw is a reasonable strategy to employ for anyone.
Note: Vegetables in the Brassica family include broccoli, cabbage, bok choy, brussel sprouts, canola, cauliflower, collard greens, kale, kohlrabi, mizuno, mustard greens, rapeseed, rapini, rutabagas, tatsoi and turnips.
Yes. If you have Hashimoto’s, then avoiding anything that causes inflammation or provokes any immune reaction ranging from an allergy to sensitivity or intolerance is wise. Eating the right low-immune-aggravating diet can go a long ways toward impacting your Hashimoto’s.
So, what are those foods?
Gluten and dairy lead the pack for common proteins that poke a stick at a sensitive immune system, but there could be many others more unique to you. Note that many foods often called “hypoallergenic,” like rice or quinoa, may be actually a problem for you, too.
This section is an update in response to the many comments and questions we received about our gluten recommendations when this article was first published.
To be clear, not everyone has to avoid gluten. Also, not everyone with Hashimoto's will eliminate gluten and feel great again.
Gluten may not be that big a deal for you as an individual, but the research is significant that it plays a role for most people with Hashimoto's. It's hard to say one thing is bad across the board for everyone, even everyone with the same disease. There are studies that show the correlation is indeed significant and not anecdotal when it comes to Hashimoto’s4.
Looking at all the evidence on gluten in relation to Hashimoto's, we see this: it's not bad for everyone, but it is a very big deal for some. If you're feeling crappy and appear to have normal labs, it might be worth a try, right?
Hashimoto's and hypothyroidism are so complicated, and food is just one variable that may be at play for you. If you tried going off gluten and you still didn’t feel better, something else is clearly at the root for your case—beyond bread.
For example, stress and inflammation can impact everything from T4 to T3 conversion to lowering active T3 by increasing reverse T3. Those are just a couple ways other factors could be still keeping you feeling badly and overall making you more hypothyroid—none of which have anything to do with gluten and wouldn't change much by going off it.
Estrogen and testosterone issues will affect the levels of free T3, meaning you get less active hormones to work on your cells. Again, not much to do with gluten, but it's another way you could still be feeling badly.
It's important to note that neither of the above appear on the typical thyroid panel that most women get, and neither would get better with a bump up in T4 meds like Synthroid. If we take out certain foods and don't feel better, those foods may indeed be no biggie for you, but it may also be that other factors are impacting your thyroid and keeping you still feeling sluggish. In practice though, often we fix those and bam! Food issues becomes a bit more clear, with more obvious symptoms.
I can't stress enough that going gluten-free will not be every woman's solution for thyroid symptoms, but the evidence is strong enough to warrant at least a trial period off of it. In my practice—which is almost exclusively women with Hashimoto's—nine times out of 10 they get at least a small, but noticeable improvement.
My approach to this stuff is always to do what will help you be better. Consider other foods that may aggravate you specifically. For example I have some patients who are so sensitive to guar gum (found in a lot of packaged foods) that it totally wrecks them. Who knew? There could be foods other than gluten causing way bigger issues for you. Most importantly, don't forget that it may not even be the food, it may be the many other points of trouble along the thyroid cascade—from brain, to thyroid production, to liver conversion, to protein binding globulins, to healthy thyroid receptors—that may be the thing that will help you feel better.
So, if you're not feeling better from going off gluten, don't give up. There are lots of other avenues to explore to help you feel great again.
To know for sure, you can get reliable testing through Cyrex labs. “Array 3” tests for multiple ways you can react to gluten (well beyond Celiac) and “Array 4” tests pretty much everything else: gluten-free grains, dairy, soy, egg, and common ingredients in gluten-free products such as tapioca and teff.
Or, you can do it the old fashioned way: an elimination diet. Consider something like Whole 30 or work with someone to help you systematically take foods out and add challenge foods back in to see if you can detect which foods make you feel worse.
Feeling worse meaning: worsening of any hypothyroid symptoms, gas/bloating, diarrhea/constipation, skin breakouts, anxiety, sleepiness, etc.
Finally, avoid anything that makes your blood sugar less stable. Blood sugar swings puts the heat on the adrenals, and in time that heat toasts the thyroid as well.
Sugar and simple carbs lead the pack here, but we all react differently to different carbs in varying amounts, so finding your unique carb tolerance (UCT) is helpful.
Also, eat as frequently as you need to—that's three meals for some, but maybe four for others. And of course, plenty of protein and fibrous veggies at each meal will keep your blood sugar more level.
Broccoli is unlikely to be “shutting down your thyroid,” but other foods may be aggravating the over-active immune system found in Hashimoto’s and worsening the attack and destruction of your thyroid.
If you’re going to take the time and effort to adjust your diet for better thyroid function, be sure you’re avoiding things and making dietary changes that will make the biggest difference for you.
Fine-tuning your nutrition is one way to improve your thyroid function. How you exercise can also hurt or help conditions like Hashimoto's. If you're looking for a balanced, sustainable exercise program, we can help.
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