What foods should I avoid with underactive thyroid

Hi, I have been taking levothyroxine since I was born (32 years) I have an underactive thyroid. Would anyone be able to advise me on what foods to avoid , I have read that I should avoid cauliflower and root veg is this true? I currently take 100mg of levothyroxine a day and suffer from itching especially on my legs, does anybody else experience this? When I went to the doctors they weren't helpful, said it could be my washing powder but I am sure it's been since reducing my meds.

13 Replies

I'd tend to agree it's due to reducing your meds. It sounds like you unfortunately have a doctor who treats your blood results rather than you. (You're probably too young to remember The Prisoner - "I am not a number!!" :) ).

With congenital hypothyroidism, I suspect you may not to worry as much about goitrogenic foods as those with autoimmune issues though I may be wrong.

Do you have any blood test results to share?

Thanks for the reply lily may. I don't have any blood test results, is the doctor meant to send me them? I will ask the doctors for my results as they have been checking my bloods every 6 weeks and all they say is my results at low, I have asked them why they are reducing my tablets if my results are low but the receptionist who is telling me this doesn't understand herself.


Just ask the surgery for a print-out of your blood test results with the ranges. As you have been taking levothyroxine since being born, they should not be adjusting your medication due only to the TSH result. Some doctors believe that's right but it can cause the patient problems. When you go for blood tests, don't take levothyroxine before take it afterwards and have the blood test as early as possible.

See link below and the first and second questions/answers may be helpful. There are also other topics if they interest you at the top of the page. Links within may not work as Dr Lowe died two years ago and the site is now archived.

I came across a paper the other day which suggested that those born without a thyroid may need slightly higher levels of thyroid hormones. Will try to look it out.

Here it is:

Eur J Endocrinol. 2014 Nov;171(5):615-21. doi: 10.1530/EJE-14-0621.

The different requirement of l-T4 therapy in congenital athyreosis compared with adult-acquired hypothyroidism suggests a persisting thyroid hormone resistance at the hypothalamic-pituitary level.

Bagattini B1, Cosmo CD1, Montanelli L1, Piaggi P1, Ciampi M1, Agretti P1, Marco GD1, Vitti P1, Tonacchera M2.

Author information



Levothyroxine (l-T4) is commonly employed to correct hormone deficiency in children with congenital hypothyroidism (CH) and in adult patients with iatrogenic hypothyroidism.


To compare the daily weight-based dosage of the replacement therapy with l-T4 in athyreotic adult patients affected by CH and adult patients with thyroid nodular or cancer diseases treated by total thyroidectomy.


A total of 36 adult patients (27 females and nine males) aged 18-29 years were studied; 13 patients (age: 21.5±2.1, group CH) had athyreotic CH treated with l-T4 since the first days of life. The remaining 23 patients (age: 24±2.7, group AH) had hypothyroidism after total thyroidectomy (14 patients previously affected by nodular disease and nine by thyroid carcinoma with clinical and biochemical remission). Patient weight, serum free thyroid hormones, TSH, thyroglobulin (Tg), anti-Tg, and anti-thyroperoxidase antibodies were measured. Required l-T4 dosage was evaluated. At the time of the observations, all patients presented free thyroid hormones within the normal range and TSH between 0.8 and 2 μIU/ml.


Patients had undetectable Tg and anti-thyroid antibodies. The daily weight-based dosage of the replacement therapy with l-T4 to reach euthyroidism in patients of group CH was significantly higher than that in those of group AH (2.16±0.36 vs 1.73±0.24 μg/kg, P<0.005). Patients of group CH treated with l-T4 had significantly higher serum TSH levels than patients of group AH (P=0.05) as well as higher FT4 concentrations.


To correct hypothyroidism, patients of group CH required a daily l-T4 dose/kg higher than group AH patients, despite higher levels of TSH. The different requirement of replacement therapy between adult patients with congenital and those with surgical athyroidism could be explained by a lack of thyroid hormones since fetal life in CH, which could determine a different set point of the hypothalamus-pituitary-thyroid axis.

© 2014 European Society of Endocrinology.



[PubMed - in process]


Have you by any chance changed the brand of medication you are taking?

I have experienced itchy legs before when I was on Levothyroxine and it might be worth checking your patient leaflet for side affects.

Regarding goitrogenic vegetables,I think that as long as they are well cooked( we steam ours) then you should be OK though have to admit that overcooked Cauliflower is not very appetising!!

NEVER let your doctor reduce your meds based on blood tests!! Ensure any vegetables such as broccoli, cabbage and other goiter inducing veges are COOKED properly and thoroughly!!

Soy is to be avoided. Cruciferous vegetables are best eaten sufficiently but not over-cooked, and shouldn't be exuded as they add important nutrition to your diet. However I've read a number of articles that say that even if eaten raw (I put broccoli in fresh fruit juices if there is some around in the fridge) it is okay so long as it's only in moderation. If you feel uncomfortable with that, definitely eat the veg cooked.

Thank you for all of your advice

Sohie, as you've been hypo since birth, I would ask the GP to add some T3 (liothyronine) to your T4 (levothyroxine) as T3 is the active hormone we need particularly in our brains as they contain the most receptor cells of which we have billions in our bodies. They have NO reason to reduce our medication according to the TSH that can interfere badly with our metabolism and make us feel much worse.

You've never really known what a fully normal health should be like so I think an addition of T3 would be very helpful.

When you get your medication, take note of the make and get the same one each time, so that if you have a problem (like itching) you can ask the pharmacist for another manufcturer to see if it makes a difference.

I have a under active thyroid I was getting a lot itching all over my GP prescribed me a tablet for 1at night named Hydroxyzine 25mg its green in colour it's stopped my itchy ness hope this can be useful to you pat

It is important to take treatment for your underactive thyroid disease, because it might cause a lot of other problems, like an eye disease. You have also to be careful with what you eat because it can affect your thyroid gland and interfere with your treatment. Some foods you need to avoid are Soy, broccoli and cabbage and other Cruciferous Vegetables because it can interfere with the production of thyroid hormone. Also, minimize taking gluten, fatty and sugary foods, processed foods, coffee and alcohol. Lastly, do not take too much fiber.

I had awful itching on my limbs and dry flaky skin. I hardly itch now, I have been gluten free for about a year. It does help, try it, you will know in about 4 weeks. Good luck

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