A post on Endocrine Web re Hypothyroidism and ... - Thyroid UK

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A post on Endocrine Web re Hypothyroidism and diet


Not sure about this. Any thoughts?

Diet - You’ll want to avoid eating lots of goitrogens, which can impede thyroid function. Unfortunately, these foods are very popular, and they include spinach, soybeans, strawberries, sweet potatoes, broccoli, and Brussels sprouts, among others. A full list of foods to support thyroid function ..(sic) ..It’s important to note that eating too much dietary fiber (think oatmeal, beans, nuts) can impair the absorption of thyroid hormone replacement medication.


14 Replies

You'd have to eat an awful lot of goitrogens - like cabbage soup every day for the rest of your life, four times a day - for it to have an effect on your thyroid.

What goitrogens do is block the up-take of iodine by the thyroid, so they can't make as much hormone as necessary. But, if you're on thyroid hormone replacement, you thyroid isn't going to be making thyroid hormone, anyway. So, how are goitrogens supposed to affect you? They aren't. And, if you cut all those goitrogens out of your diet - and the list is much longer than just cabbage, broccoli and Brussel's sprouts, and includes things like walnuts and pears - you're going to miss out on a lot of nutrients. So, ignore that bit.

The only exception to that is soy. As well as being a goitrogen in the normal sense of the word, soy has the ability to block the up-take of thyroid hormone by the cells. So, you can have good levels in your blood but still be hypo. So, best to avoid that in all its forms: soy oil, soy flour, soy protein, etc.

That is correct about too much fibre. If a high-fibre diet is rushing your exogenous thyroid hormone through your gut, it could be out the other end before it's had time to be absorbed - especially if it's slow-release. But, on the other hand, a lot of us hypos are constipated, so we do need a decent amount of fibre. So, like most things, it's a question of finding the right balance. :)

Thats fantastic news! I love spinach etc and yes I do ‘need’ porridge to be ‘regular’ . Many thanks

You're welcome. :)

Redlester in reply to greygoose

if you are taking your hormone in the middle of the night on an empty stomach would it not be getting into the bloodstream quickly, which would mean if you eat high fibre during the day then you aren't losing it? I ask because I need high fibre and take my T3 in a single dose in the middle of the night.

greygoose in reply to Redlester

I can't answer that question. And probably no-one else could, either. I don't think there's been enough research done on it to know.

What you could do is compare your FT3 level with your dose, to see if a reasonable amount seems to be getting through. Do you have a recent FT3 test results?

Redlester in reply to greygoose

Thanks GG. I started self treating with T3 in January so only have pre-treatment test results available at the moment. I am due to do a set of medicheck tests to see what is happening. I was just applying logic in what I posted previously, i.e. if it takes 7 hours for the T3 to be utilised and I take mine in a single dose in the middle of the night then it would be in my system before I eat and if you also add in the time it takes for food to move from the stomach to the colon [where the fibre would be relevant] then sufficient time should have elapsed to stop the fibre preventing the T3 being utilised by my body - no? Either way, I have to continue to go with the fibre for all of the health benefits it confers, and if you were to eliminate all those high fibre foods you would be losing a lot of beneficial nutrients and eating a very bland an unhealthy diet to my mind. The T3 will just have to do its best to compete!!

greygoose in reply to Redlester

What do you mean by it takes 7 hours for the T3 to be utilised ?

Do you meant to be absorbed? Because it's not really the way hormones work. And, there are so many factors involved in it being absorbed from the gut, and then carried round the blood and taken up by the receptors. And, the gut is never completely empty. It's not like draining a bath: i.e. you eat and it goes straight through. I don't think you can calculate the time scale of all this with logic. And, it's not like the fibre blocks the absorption of T3, but that it could hurry it through the colon and out the other side before it has time to be absorbed. So, it depends on the speed of your gut motility. So many things could affect all that, that I don't think you could calculate it except by comparing your FT3 blood levels with the size of your dose, as I said. See if it looks like a reasonable amount is getting into the blood. But, even then, there are many other factors that could affect it, not just fibre intake.

But, nobody ever suggested you should cut out all high fibre foods. I agree, that would be rediculous. You still need them, especially as hypos tend to be constipated. Just bear in mind that too much - whatever too much might be - could affect the absorption of your thyroid hormone. Which is what was said in the original post. And, I wasn't arguing with you, I just said that it is a complicated subject, which no-one - to my knowledge - has ever studied in depth, so your question is - and remains - unanswerable with total accuracy. The best one can say is: it all depends.


Your post from 10 days ago shows you are under medicated


Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Is this how you do your tests?

Ft4 only 25% through range

Ft3 30% through range

Helpful calculator for working out percentage through range


Did you get 25mcg dose increase in levothyroxine?

I was raised 25 in late 2018 to 125 and nothing since.

SlowDragonAdministrator in reply to Loafinabout

So you need to ask GP to agree to 25mcg dose increase in levothyroxine up to 150mcg ....as a trial if necessary

Improving nutrients improves conversion


NICE guidelines



Consider starting levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.

BMJ also clear on dose required



You also need to test vitamin D

Test twice yearly via vitamindtest.org.uk

Thanks so much for this feedback - using percentages very useful and link much appreciated.

Will do and have just received Vit D 3000 Oral spray and ditto VitB12 1200ug both from Better You. Thankyou for advice.

Thanks so much for this advice and I will do that

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