Association between dietary onion intake and su... - Thyroid UK

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Association between dietary onion intake and subclinical hypothyroidism in adults: a population-based study from an iodine-replete area

helvella profile image

What a very odd paper - which really doesn't get anywhere in terms of explanation. Nonetheless, it does raise my curiosity as to what might be happening and why.

Pickled? Scallion? Raw? Cooked? Red, white or brown?

Endocrine. 2021 Jul 31.

doi: 10.1007/s12020-021-02790-2. Online ahead of print.

Association between dietary onion intake and subclinical hypothyroidism in adults: a population-based study from an iodine-replete area

Juanjuan Zhang # 1 , Yeqing Gu # 2 , Ge Meng 3 4 , Qing Zhang 5 , Li Liu 5 , Hongmei Wu 1 , Shunming Zhang 1 , Yawen Wang 1 , Tingjing Zhang 1 , Xuena Wang 1 , Xu Zhang 1 , Xing Wang 5 , Shaomei Sun 5 , Ming Zhou 5 , Qiyu Jia 5 , Kun Song 5 , Kaijun Niu 6 7 8 9 10


• PMID: 34331679

• DOI: 10.1007/s12020-021-02790-2


Purpose: The protective effect of onion against thyroid hypofunction has been reported in animal studies. However, in humans, the association between onion consumption and subclinical hypothyroidism (SCH) are unclear. The study sought to explore the association between habitual onion intake and SCH among adult population from an iodine-replete area.

Methods: A cross-sectional study (6515 men and 5290 women) was performed in Tianjin, China. Frequency of onion consumption was assessed using a valid self-administered food frequency questionnaire. Serum free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were determined by chemiluminescence immunoassay. SCH was diagnosed with TSH > 4.78 mIU/L. Multiple logistic regression was used to evaluate the association of onion intake with SCH.

Results: The prevalence of SCH was 2.56% in men and 7.18% in women, respectively. In women, the fully adjusted odds ratios [95% confidence interval (CI)] of having SCH across increasing frequency of onion intake were 1.00 (reference) for <1 time/week, 0.99 (0.73, 1.34) for 1-3 times/week, 0.74 (0.53, 1.03) for 4-6 times/week, and 0.67 (0.47, 0.97) for ≥7 times/week (P for trend <0.01). However, we observed no significant association between onion intake and SCH in men. Stratified analyses suggested a potential effect modification by age: the odds ratios (95% CI) across extreme quartiles was 0.37 (0.17, 0.80) in <40 women and 1.11 (0.51, 2.47) in >60 women.

Conclusions: Frequent consumption of onion is inversely associated with SCH in adult women from an iodine-replete area. Further studies are needed to explore the casual relationship. TRIAL REGISTRATION WEBSITE:

Keywords: Adult population; Diet; Onion; Subclinical hypothyroidism.

Full paper not available:

40 Replies

Thank you helvella, interesting! I recall that celery paper!!

interesting . but i doubt my grannie would be surprised by the results of 'sub-clinical onion consumption'

how does anyone manage to only eat onion 1 time a week ?

i'm not sure i know how to cook anything for dinner that doesn't start with 'an onion' (or 6)

Onion Juice Smoothie ? anyone ? p'raps not......

helvella profile image
helvellaAdministrator in reply to tattybogle

Also unclear whether the effect is also achievable by other members of the Allium family such as leeks, garlic, shallot, etc.?

Were I asked if I had consumed onions, in some survey, I might well say "No" even if I had just eaten a bowl of leek and potato soup. Unless they were very clear what constituted "onions".

Helvella thank you for another very interesting and informative post. It accord to me that many might be on on Quercetin supplement for inflamation or for allergy purposes. That might also be something to consider if onions are counter productive for us on thyroid meds depended.

tattybogle profile image
tattybogle in reply to jgelliss

Onions not counter productive. Onions good. Eat more onions .

more frequent onions = less cases of TSH over 4.78.

less frequent /no onions = more cases of TSH over 4.78.

jgelliss profile image
jgelliss in reply to tattybogle

I love onions. It gives great flavors to almost anything.

helvella profile image

Wouldn't that be the opposite effect to what the paper reported?

Frequent consumption of onion is inversely associated with SCH in adult women from an iodine-replete area.

jgelliss profile image
jgelliss in reply to helvella

I'm still in a limbo about onions. I love them . But is it good for us thyroid depended patients?

jgelliss profile image
jgelliss in reply to helvella

Helvella would you know if onions and some other more sensitive kind of foods are a no no even for those of us that had TT? Because if I remember correctly my surgeon at the time who is unfortunately no longer with us . He is in Heaven giving his thyroid advices. To me at the time since my thyroids where removed and that I was on total thyroid replacement that I was allowed to eat everything. Does that still stand today ? Or are there other or better understandings today? I know that with time they know more. I also believe that there is always room for improvements. Thank you.

Very interesting . Thank you Crabtree. This was a very interesting and eye opening article. I will be more mindful in the future with my food and nutrient picks. I was just thinking for e.g. does onions in raw or cooked formate make a difference for us on thyroid meds?

helvella profile image

Not at all convinced by that!

i think my grannie would say "what a waste of good onions.. they don't grow on trees you know..."

Mind you ..they're powerful things these alliums..... i once misunderstood some drunken instructions for how to make a garlic poultice (to get a blackthorn splinter out of my blokes elbow) i put the whole squashed clove on with a bandage,, and told him not to be a wuss when he kept complaining it was stinging ... next morning there was big hole in his arm ..oops ... mind you the splinter was fixed.

In AC Bianco’s 2019 paper The Deiodinase Trio he advocates using leeks and red onion for hesperidin a constituent of Vit b2 that increases D2 by up to 50-fold. I have increased my leek consumption to test the theory in an ad hoc way, but not found any difference. Perhaps other thyroid pathway polymorphisms intervene in my case instead?

i haven't heard of black jack ... hence the attempt at garlic poultice. it seemed worth a try based on previous astonishing success of a bread poultice, magically drawing green gunk out of an infected blister overnight.

I think i remember a bottle of 'Kaolin and Morphine' in our bathroom cabinet ? not sure what you had to have wrong with you to be given it was next to some foul smelling mustard coloured stuff a little brown jar which was put on scraped knees that had gone manky.

for some obscure reason my dad used to get me to rub two sugar cubes together over a scraped knee..... i can't imagine sugar would be any good for healing ? perhaps it was just to give a sqwaaking kid something to do ? or maybe he knew something we 've forgotten.

I know honey is good for healing stuff, but white sugar ? ....surely not .

I've always wondered ...what exactly is a carbuncle ? prince charles once said a new building near our house was a carbuncle...

You seem to be dippng into my Mum's old medicine cabinet - do I know you ?

My Mum was a firm believer in a hot bread poultice - it worked for her as I never complained about anything, ever again.

I think the K & M was also there, and it did the trick, as I never complained again about a stomach ache.

Onwards and upwards !!!

no, my mum had new fangled ideas like plasters and if you were really ill ,lucozade from the chemist with the nice shiny paper.I was led astray later to poultices, by naughty women in the woods.

Might have preferred a hot bread poultice on my knees.. the plasters used to stick to the goo oozing from my manky knees and take an hour in the bath to soak off.

Never did find out what was in the mustard coloured ointmnent though . it didn't have a label, and seemed to have been in the cupboard since 1886. With hindsight i wonder if it had iodine in it.

When I was around 11 my hair fell out in little clumps about the size of the now 50 pence piece - I was given iodine to paint on the spaces created.

The suggestion was that maybe I was a bit nervous when I took the 11 plus -

Well that was the understatement of the year as I was undiagnosed dyslexic and left handed and a nervous wreck from a very young age, only I didn't recognise it as anything, as I thought everyone felt the same.

These patches were a browny/ dirty yellow colour :

I wonder if there's a study anywhere on statistics re. parents daubing Iodine on their kids for apparently random reasons / kids ending up thyroid problems ?

it might conclude that taking the 11 plus and / or " falling off your tricycle a lot" is a risk factor for hypothyroidism.

(don't laugh .. yes i know it's really difficult to fall of a tricycle )

was iodine supposed to help you hair grow back ?.. i don't suppose having orange patches on your head made you feel any more confident about anything .

I 'm a lefty too . but i changed hands .. so now i'm either ambidextrous or useless depending the subject to hand. .. but weirdly i can now do joined up mirror writing with both hands at once . which is fascinating but not particularly useful.

I do wonder what changing hands did to my brain though .. (maybe it messed me up cos i used to pull my own hair out . so i too had a 50p sized bald patch )

TSH110 profile image
TSH110 in reply to pennyannie

Gentian violet (a very marvellous potion), mercurichrome (that must have been dangerous stuff) and calamine lotion were some things I can remember in our cabinet as a youngster.

TSH110 profile image
TSH110 in reply to tattybogle

A carbuncle is very nasty indeed. A pal had one and said it was like a tree 😱 spreading inside him it was a job to finish it off too.

I too recognise that medicine cupboard and would add the dreaded Kaolin Poultice… whenever we got a chest cold Mum would heat a tin of this evil stuff and smear it between two cotton hankies and then stick it on our chests overnight… it smelled foul and in the morning you’d wake up with a solid, cold slab of this stuff that would then be broken up and put back into the tin for the next night! I’m not sure what its purpose was, but it was foul and it never worked! And then there was Pulmo Bailey! You were required to drink this stuff in hot water and it would magically get rid of a bronchial cough! Combine the two and you have my childhood memories of having colds! I can still recall the smell of my mum’s medicine cabinet!!! 😂

I sadly remember the dreaded Kaolin Poultice! I hit my finger once with a hammer and it went septic-was t very old! Dad but a poultice on it and sent me off to bed. The next day I was going to the doctors with my gran. She was a regular customer as had PA so had bloods done often so I had to take along. Dad had told me if the covering hadn’t shown the nasty stuff had come out then doctor would lance it and explained what that meant. So wasn’t looking forward to it. Gran had her injection so I wasasked to take the dressing off! Sadly it hadn’t burst so I was petrified but at the last moment-relieve! Won’t go into details as not pretty but doctor was delighted!

Anthea55 profile image
Anthea55 in reply to tattybogle

That Kaolin and Morphine mixture was for settling your stomach if you'd had diarrhea for too long. The kaolin is china clay and would bung you up for a while. Just googled for it and it seems to be still available to buy over the counter.

helvella profile image

Sugar often acts by osmosis. Dry sugar (or a strong solution of sugar such as honey) absorbs water from anything damp or wet close by. That means it draws the water out of both the swollen tissue and the liquid content of the cells of any bacteria that are present.

Wiki article on osmosis:

tattybogle profile image
tattybogle in reply to helvella

Ah . maybe my dad wasn't so far off with his sugar cube grating then,.... it took them years to find out the only way to heal my skin was to not cover it up and put something called EDP on it, which was like pink talcum powder.

helvella profile image
helvellaAdministrator in reply to tattybogle

Povidone iodine - I think!

tattybogle profile image
tattybogle in reply to helvella

well blow me, so it is .. i thought they weren't allowed to sell it anymore. a chemist told me that decades ago when i couldn't find any more .. i was gutted.. but just looked online and it still exists. Fortunately i don't fall off things so much nowaday's, so i have managed without.

helvella profile image

You could look at it like that!

When bacteria are exposed to sugar, they lose water, and shrink. It doesn't always kill them, but it stops them reproducing and slows their metabolism.

To a considerable extent, salt would have the same effect. Hence we see both salt and sugar used for preserving foods.

(This is in the realms of physical chemistry. Whereas many other preservatives, antibiotics, etc., act by being toxic to bacteria.)

thanks for that :) I see what he meant about the building now

Are we sure that lump on the back of his neck isn’t just a red onion??


Jazzw profile image
Jazzw in reply to Jazzw

The carbuncle picture has now disappeared - there was one on this thread earlier, if anyone’s confused as to why I made such a weird comment. :)

tattybogle profile image
tattybogle in reply to Jazzw

yes . one minute i was chatting to someone called crabtree ? about carbuncles and poultices . as you do .. and then. ...poof ... no such person exists, and neither does anything they said.... i hope it was nothing i said. Anyway .. this thread that is (allegedly) about onions, will now and forever after , look somewhat surreal.

(but you're right . it did look suspiciously like a slightly mouldy red onion)

yes, now i drag my memory i think the mustard looking stuff might have been referred to as 'poultice' It was years later when i learned that 'a poultice' was the way of applying the thing rather than the thing itself.

TSH110 profile image
TSH110 in reply to tattybogle

It could well have been mustard, there are some interesting possibilities mentioned here:

Onions are in there too

tattybogle profile image
tattybogle in reply to TSH110

fascinating.. but it smelt a lot more 'dangerous' than mustard, more like a cross between sulpher / diesel / meths

TSH110 profile image
TSH110 in reply to tattybogle

Yeah it could have had all sorts of powerful things in it. The mercurichrome in our cupboard must have had mercury and chrome in it. I know mercury has been used in medicines since at least the Middle Ages I even have a feeling that mercury is still used. Chrome is pretty poisonous. I bet that stuff killed any bug and if you were not very careful, the patient too!

Surprise surprise it’s been banned by the FDA in part because of the ingredients and because it didn’t kill the bugs either:

helvella profile image
helvellaAdministrator in reply to TSH110

Even if the product itself had little or no toxicity to the user, we have issues with the manufacturing plant, and with disposal.

People do put such stuff down the drains, and much that was applied will end up being washed off. Sometimes the amount of a substance entering sewage works (or septic tanks) is a significant problem. For example, radio-active iodine from medical use near large medical facilities.

TSH110 profile image
TSH110 in reply to helvella

Bit scarey. I knew fish did well near nuclear reactors because of upping the water temperature perhaps also radioactive live fast die young fish I guess! But frightening it’s out there just floating around do we just have rubbish protocols and protections, or is is everywhere doing this? For sure putting mercury containing potions down drains is not at all good. I have no idea what happened to that little bottle of evil stuff either.

TSH110 profile image
TSH110 in reply to tattybogle

Mind you mustard gas was pretty evil stuff…but I discover it only smelt like mustard, garlic or horseradish it was never concocted from mustard.

More association between iodine sensitivity (onion related) and hypothyroidism. The research on iodine balance and how it relates to thyroid disease continues.

Thanks for the paper.

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