This isn’t meant as an in dept review of goitrogens. It’s just very important for me to clear up some misunderstandings about hypothyroidism and goitronic food. It seems like very few have realized what I have realized. I see bloggers and doctors and people on Facebook claiming, people suffering from hypothyroidism should avoid goitrogenic food. But that is wrong, people with thyroid disease can absolutely eat goitrogenic food. I will expain why:
What are goitrogens?
Goitrogens are substances that inhibit the production of thyroid hormones. It’s mainly by inhibiting iodine uptake in the gland. As you know, thyroid hormones consist of iodine and tyrosin. So without iodine, no hormone production. Soy also seem to maybe interfere with the TPO enzyme. I am not sure if this has been 100% established. TPO is paramount for hormone production. I write about that here.
I will only talk about goitrogenic food here. The word “goitrogen” comes from the word “goiter”. Goiter is usually a result of the gland not catching enough iodine. It swells up to catch more iodine, and you have a goiter. Too much iodine can also cause goiter.
But iodine deficiency is a main cause of goiter. And studies also show, that it is when there is iodine deficiency that goitrogens are a problem. You find several studies on goitrogens here https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/goitrogen
There are also goitrogens that interfere with thyroid hormones in other ways, but those are goitrogenes in chemical substances, not in food. Some medicines can increase the degradation of T4 and T3.
This is a table of goitrogens and their actions from the link above.
Table 7. Goitrogens and mechanisms of action.
| Goitrogen | Proposed mechanisms | Dietary source |
|---|---|---|
| Thiocyanate | Cyanogenic glucosides are metabolized to thiocyanates that compete with iodine for thyroidal uptake | Cassava, lima beans, linseed, sorghum, sweet potato |
| Glucosinolates | Glucosinolates and metabolites compete with iodine for thyroidal uptake | Cruciferous vegetables (e.g., cabbage, kale, broccoli, cauliflower, turnips) |
| Flavonoids | Impair thyroid peroxidase activity | Soy, millet |
| Goitrin | Reduces production of thyroid hormones | Cabbage, brussels sprouts, rapeseed |
| Iodine | Excess iodine intake causes thyroid dysfunction | Iodine-containing foods, drinking water, or supplements |
| Smoking | Increases serum thiocyanate that competes with iodine for thyroidal uptake and transport into the secretory epithelium of lactating breast | |
| Perchlorate; nitrates | Competitive inhibitors of iodine uptake into the thyroid gland | |
| Polychlorinated (PCB) and polybrominated (PBB) biphenyls; 2,4-dinitrophenol | Alter thyroid hormone metabolism | |
| Disulfides | Reduce thyroidal iodine uptake | |
| Lithium | Inhibits thyroid hormone synthesis and release |
(Jesse Bertinato, in Advances in Food and Nutrition Research, 2021)
Can hypothyroid eat cabbage?
Yes, people suffering from hypothyroidism can eat cabbage. I assume you don’t eat several pounds/day. If you are juicing, then you get a large amount.
Why can we eat goitrogenic food? Because we don’t produce thyroid hormones anylonger. So for us, the goitrogens in food have no detrimental effect. If you have been hypothyroid for years, and need a dose of 100 mcg T4 or more, you are not producing. You might have a very small rest production. One sees this in people on T3 mono teraphy. Some have a FT4 of cero, and others have a FT3 somewhere under 5 pmol/L (0.3 ng/dl), even after a long time on T3 mono.
I don’t think I have any rest production, I have only a pea left of my thyroid. But you never know. It’s not important to me. It is important for me to eat some broccoli and cabbage. I adjust my thyroid levels with my meds. Even if you have a rest production, you can safely eat some goitrogenic food, see below.
It’s people who are thyroid healthy who have to be a bit careful with goitrogenic food. Especially if they are iodine deficient. And if you are in the beginning of thyroid disease, and you are trying to stop it from progessing, then it’s wise to stay away from too much goitrogens. It’s very important to understand, that it is when one is iodine defcient, that goitrogens in food poses a problem for those without thyroid disease. But us with chronic hypothyroidism can eat goitrogens and not worry.
Don’t forget that people with AITD need iodine even if we don’t need it for thyroid hormone production. All our glands need iodine, and it’s a very powerful antioxidant in the body. I don’t know if goitrogens can inhibit iodine uptake elsewhere in the body, but if we make sure to be iodine replete, I don’t think that would be an issue. You can find info on safe iodine supplementation here, Iodine for beginners
I think this is important information.People suffering from AITD very often have digestive issues. If you have elevated anti-TPO, you need to stay away from gluten. Many don’t eat dairy. I personally can’t eat eggs. If we on top of that avoid soy, cabbage and glutenfree grains like sorhum and millet. For no reason. Then I think it adds stress to our lives. I think it is so importan that we don’t stress. Worry goes straight to our adrenals. I write about the importance of inner peace here. Our state of mind is so important for our well being. So let’s at least not worry about goitrogens!
Some facts
This post is meant for hypo thyroid with little or no rest production. But even if you still produce some hormone, you can eat food with goitrogens. Some foods can poise a problem, and some medications, like lithium, can really damage our thyroids. But lithium can be very important for someone’s mental health, so it’s not like one shouldn’t take it. But I don’t think doctors give patients the necessary info on potential damage to the thyroid. But that’s another matter.
Here is a study showing how much goitrins and thiocynats you need to eat before it’s a problem. study.
there are no data on concentrations of goitrin in human plasma following the ingestion of brassica vegetables, which could be helpful in establishing nutritional safety guidelines. One study assessed the change in radioactive iodine uptake by the thyroid glands of human subjects following the administration of recrystallized goitrin.23 The authors reported that 25 mg (194 μmol) was the minimal amount of goitrin required to decrease the uptake of radioiodine; in contrast, a smaller ingested amount, 10 mg (70 μmol), caused no inhibition of uptake.
So one has to eat at least 25 mg (194 μmol) of goitrin to affect the iodine uptake in the thyroid. Keep that in mind.
It varies widely, how much goitrin the different goitin rich vegetables contain.
the brassica vegetables were categorized into 3 classes: (1) those with progoitrin concentrations over 100 μmol/100 g of fresh weight [i.e., the Siberian (Russian) kales belonging to the species B. napus, one collard (B. oleracae), and one Brussels sprout (B. oleracae)]; (2) those with goitrin concentrations between 10 and 100 μmol/100 g of fresh weight [i.e., Chinese cabbages (B. rapa), some collards, and Brussels sprouts]; and (3) those with goitrin concentrations less than 10 μmol/100 g of fresh weight [i.e., turnip tops, some Chinese and Japanese greens, commercial broccoli rabe (B. rapa), commercial broccoli (B. oleracae) varieties, and the kales belonging to the species B. oleracae].
The ones to be a bit careful with, are brussel sprouts, brassica napus ie. rapeseed and collard greens. The latter is a looseleafed cabbage. We don’t use it much in Scandinavia. We eat another form of kale here. I assume it’s what they eat in The south in the US. It is also eaten a lot in Africa. If you love it, don’t despair. Look under “cooking”.
While broccoli, califlower and cabbage contain less goitrin, and you have to eat a lot for it to affect your thyroid. For those who has a functioning gland. Bok choi and napa cabbage contain very little goitrin. You can safely eat some raw even it you are thyroid healthy.
What they say, is that you have to eat 25 mg goitrin for it to inhibit iodine uptake in the gland. 100 grams of raw broccoli contains 10 mg goitrin. Even if you have a little hormone production, you should be able to eat some raw broccoli every once in a while.
This study is quite complex. The subject is quite complex.
Soy
People who are thyroid healthy and eat large amount of soy every day, might have reason for concern. Us with a thyroid disease can safely eat soy in normal amounts.
In this study (on animals), they find that goitrogens in soy do interfere with the TPO enzyme. Depending on how much one eats, study But even so, they found no changes in TSH, FT4, FT3, thyroid volume or histological changes (damage to the gland). They conclude that there must be other factors present at the same time for soy to have a detrimental effect. And what they say here is very important:
Iodine deficiency greatly increases soy antithyroid effects, whereas iodine supplementation is protective.
Again, iodine is SO important. And so many of us are deficient.
Here is another interesting study, a metastudy, that is a review of several studies. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408586/
They looked at 18 studies on soy and thyroid function. In the studies, they found no changes in FT4 or FT3, but a slight change in TSH of 0.248 MIU/L.
This is a study on 44 women with subclinical hypothyroidism, study. They were divinded in two groups, and administred either 66 mg phytoestrogen and 30 mg soyprotein. OR 0 phytoestrogen and 30 mg soyprotein. Then the groups were changed after a wash out periode. 2 women became overtly hypo durng this time. I guess I would call most of them hypothyroid. But that is not the point here. They saw no changes in either TSH, FT4 or FT3.
It’s difficult to find studies saying, soy lowers thyroid levels. Not even in these subclinical women. I think I can safely say, that we who don’t produce much anymore can safely eat some soy. AND take soy products in meno pause.
But don’t take soy at the same time as your thyroid meds. 1 to 2 hours away should be ok.
Cooking
If you ARE worried about goitrogens despite everything I have told you, cook and don’t eat raw goitrogenous vedge. I am sure you know this already. It’s boiling in water that gets rid of the most goitrogens.I have taken this info from this article, article . It’s a very good article on goitrogens, but what they say about causes of autoimmune thyroiditis is rubbish.
Most cooking methods reduce goitrongens, but do not eliminate them.
Microwaving reduces goitrogens by 50%.
Steaming by 1/3.
Boiling both leaches the goitrogens out into the water, plus the high temperature destroys the goitrogens. If you boil cabbage for 5 minutes, you have a 35% reduction, for every additional 5 minutes, you get 5 to 10% more. After 30 minutes, 87% of the goitrogens are gone.
I think that something like collard greens, even though very goitrogenic, it’s something you boil for a long time. So I would assume it would be safe.
I am not the only one who thinks, we hypothyroid can eat goitrogenic food. Here are a couple of other bloggers who have similar thoughts. Though they are not exactly on the same page, they don’t think about the not producing hormones thing. Which is my main point. But they do agree, that there is no reason to exaggerate the dangers with eating goitrogenic food.
https://www.thethyroiddietician.com/is-broccoli-really-bad-for-your-thyroid/
https://www.verywellhealth.com/thyroid-disease-goitrogens-diet-3233164
You must of course find out for yourself, what is right for you. I don’t think I have any rest production. I have only a pea left of my thyroid. But you never know. I don’t worry about that. I don’t want to live a life without cabbage, broccoli and cauliflower. I eat those things several times a week, both raw and cooked. I love sweet potatoes and I bake with sorghum. I take a pretty normal dose for someone 25 years hypothyroid without much gland left, 195 mg NDT. And I am euthyroid, with a good body temperature and pulse. So I feel that goitrogens do me no harm. And hopefully some good.
Has ANYONE published a chart showing all the cruciferous vegetables and their goitrogen content per 100g? I am very familiar with the study you cite, the information it leaves out, and the fact that apples and oranges are treated the same …. But this I mean your concern over needing to eat more that 10mg of *goitrogen* without our knowing the goitrogen content of most of the foods in question. My deal is trying to sort out how much sauerkraut I can eat in a given … day? serving? as there’s no info on that either! Is it day or serving? And sources I otherwise trust disagree on whether fermentation increases or decreases goitrogenicity … I suspect it increases. Anyway, thank you for filling in a hole or two on this. I wish they’d do studies WE need rather than just those that bring in pharmaceutical money.
Hi Diana!
I believe there are charts like that. That info is not the point of this post though. The point here, is that many thyroid patients don’t really need to worry about goitrogenic food at all. We can eat all the goitrogenes we want. If your thyroid does not produce hormones, it does not matter It’s kind of baffeling, that others seemingly haven’t thought about this. Most sites do not even tell you, what it is goitrogenes DO. They inhibit iodine uptake in the gland, especially if you are iodine depleted, and that is important. If you have plenty of iodine in your system, goitrogenes will be much less of a problem. You can read about how to safely supplement iodine here Iodine for beginners
But if your gland does not produce hormone anyway, there is no need to avoid goirtogenic foods. It’s a bit funny, that hundreds of thousands of thyroid patients don’t eat food that could do them no harm. As their thyroid is unable to take up iodine. As it is totally damaged or shrivelled up. Even people who have had thyroidectomy worry about goitrogenes. So this is the point of this post. Do you produce thyroid hormones? Have you been sick for many years? Do you need 100 mcg Synthroid or more? If that is the case, you probably don’t produce much. And you can eat all the sauerkraut you want. Which is very good for you. It’s a good thing to have an ulta sound of the gland. Then one can see for sure, what state it is in. Mine is shrivelled up, and I eat goitrogenes without worrying.
All the best, Liv