A wacky thought came to me during one of my menopausal sleepless night moments....
So, if SOYA is harmful to the Thyroid, due to suppressing it's function apparently, how come the whole of Asia who practically lives on it, doesn't have continent wide Thyroid disease? 🤔
What do other folk think? 😊
It's bewildering what pops into my head when I'm willing myself to sleep 💤 😄
Yes, I've often thought this too. I've seen the research showing that soy affects absorption of levo in the gut, but would also be interested to read any papers relating to how soy directly affects the thyroid, or, I believe I've seen it mentioned, that soy affects things more at a cellular level. Any interesting papers??
Soy is a goitrogen. Goitrogens act by impeding the uptake of iodine by the thyroid. To try and absorb more iodine, the thyroid swells into a goitre - hence the name: goitrogen.
However you would have to consume an awful lot of soy for that to happen. And I don't think many people, even in Asia, consume that much soy.
Also, there's the thorny question of is it just unfermented soy that is goitrogenic or is it fermented soy as well? We don't seem to have an answer to that at the present time.
But, it doesn't do any permenant damage to the thyroid. It's only while you're eating it that it has that effect - except maybe on babies. It has been found that babies that were fed on soy formula grow up to develop thyroid problems. I'm not quite sure how that works, though.
And I don't think that soy affects absorption of levo in the gut. But what it does do is impede the up-take of thyroid hormone at a cellular level. So, you can have good levels of T4/3 in the blood but still be hypo because it's not getting into the cells.
Actually, Asian countries do have a higher incidence of Hashi's than western countries, but that could be due to their higher intake of iodine, rather than soy.
So, the reason that hypos are advised not to consume soy, I think, is that they have limited amounts of thyroid hormones in their system. If the body needs higher levels of thyroid hormone to saturate the receptors and get it into the cells, a healthy thyroid can make it. If you are taking thyroid hormone replacement, you only have a certain amount per day and that is all you get. You can't have extra.
Please provide some links to papers. So many things get ingrained as "truths" when there's little evidence behind them and I like to get to the source!
I used to have links, several computers ago. Now, I've no idea where they are!
healthunlocked.com/thyroidu...
natural.news/2015-12-18-7-r...
thehealthyhomeeconomist.com...
wellnessmama.com/health/is-...
This is all I've found so far.
This is helpful. I'm thinking about being on replacement and "that being all you get" so extra soy you eat could use some of that limited supply up.
If you're being tested regularly and your use of soy is somewhat even/constant shouldn't it show up in labs that you're "using more up" and so are in need of an increase in your medication? Or will you just not get the benefit of all your meds and no one (including your doc) would be any the wiser?
If the hormone isn't getting into the cells then it stays in the blood for its alloted life-span. So, a blood test would suggest you are adequately medicated - and could even suggest over medication. So a doctor would not be willing to increase the dose. If you're self-treating you could increase it yourself, but how would you know by how much? Far, far easier to just cut out the soy - which has other drawbacks quite apart from that.
so extra soy you eat could use some of that limited supply up.
Soy doesn't 'use up' your thyroid hormone. It stops it getting into the cells.
I've not read anything particularly paper wise, just what I've seen on the Internet on how to manage Hashimotos and foods to avoid. Conventional medics don't seem to know of any relation between certain foods and thyroid disorders, shocking!
I’ve wondered that. They also consume large amounts of iodine via seaweed etc.
Yes, and their traditional diets are supposed to be some of the healthiest in the world, rather confusing I think. 🤔 😄
pubmed.ncbi.nlm.nih.gov/165... "Thus, collectively the findings provide little evidence that in euthyroid, iodine-replete individuals, soy foods, or isoflavones adversely affect thyroid function. In contrast, some evidence suggests that soy foods, by inhibiting absorption, may increase the dose of thyroid hormone required by hypothyroid patients. However, hypothyroid adults need not avoid soy foods. "
So there you go. Pretty much what I said. However, whether or not hypothyroid adults need to avoid soy foods depends very much on the individual.
The paper talks about soy reducing absorption of levothyroxine, but not of its affects at a cellular level in those who are hypothyroid. It also says: "In addition, there remains a theoretical concern based on in vitro and animal data that in individuals with compromised thyroid function and/or whose iodine intake is marginal soy foods may increase risk of developing clinical hypothyroidism. Therefore, it is important for soy food consumers to make sure their intake of iodine is adequate." So with a healthy thyroid soy is only really a concern when iodine intake is low.
It talks about affecting absorption. It doesn't say where. Intake of iodine would have no effect on absorption either in the gut or at the cellular levels. Iodine is to do with it's effects within the thyroid itself. I find this article rather vague.
Oh, that's interesting. Thanks! 🙂
Sorry to but in here as I’ve just come across the thread. I do find a lot of the dietary advice confusing and I dare say, alarming at points.
With iodine, which levothyroxine provides, are we ok to eat iodine rich foods? Crispy fish skin for example, or seaweed?
One issue is that the amount of soy in a western diet using multiple soy-based products (e.g. soy "milk", textured soy protein, etc.) where some people are actually likely consume more soy than most of those who live in Asian countries. (Leaving aside the issues such as fermented/non-fermented.)
I include the paper below not because it is common or typical, it isn't, but it shows what can happen in an extreme situation.
Front Endocrinol (Lausanne). 2022; 13: 927726.
Published online 2022 Aug 11. doi: 10.3389/fendo.2022.927726
PMCID: PMC9402931
PMID: 36034464
Case report: Goiter and overt hypothyroidism in an iodine-deficient toddler on soy milk and hypoallergenic diet
Angela Maria Caprio, 1 Giuseppina Rosaria Umano, 1 Caterina Luongo, 1 Francesca Aiello,corresponding author 1 , * Iride Dello Iacono, 2 Stefania Palumbo, 1 Emanuele Miraglia del Giudice, 1 and Anna Grandone 1
Abstract
Soy-based infant formulas (SFs) are often consumed by cow’s milk allergic children. However, some concerns have risen since soy intake may adversely affect thyroid function in iodine-deficient or subclinical hypothyroid individuals. We report the first Italian case of SF induced goiter and hypothyroidism registered in our country since National Iodine program has been instituted. Finally, we review cases previously reported in literature. A 22-month-old toddler with a previous diagnosis of cow’s milk protein allergy came to clinical attention for important goiter and overt hypothyroidism. Detailed dietary anamnesis revealed that he was on a restrictive dietary regimen based on soymilk since 12 months of age. A temporary levothyroxine substitution was instituted to avoid hypothyroidism complications. Adequate iodine supplementation and diet diversification completely reversed SF-induced hypothyroidism and goiter, confirming the diagnostic suspicion of soymilk-induced thyroid dysfunction in a iodine-deficient toddler. This case report demonstrates the importance of careful dietary habits investigation and adequate micronutrients supplementation in children on a restrictive diet due to multiple food allergies in order to prevent nutritional deficits.
Keywords: children, goiter, hypothyroidism, soybean, cow’s milk allergy, case report
ncbi.nlm.nih.gov/pmc/articl...
Thanks, a very interesting article.
A brilliant question. I'm glad of some considered replies - I didn't know that correct quantity of iodine was a factor in thyroid hormone being more or less available when soya included in diet. Do you or no spy has been a conundrum for me, as it is highly recommended in menopause (along with omega fatty acids, for instance from ground flax seed, chia seed, and/or sesame seed, etc). Thank you ☺.
Typo: to soy or not to soy.
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Absolutely. I'm menopausal too and soya is in almost everything now, it's getting harder to avoid.
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