Thyroid UK
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Tannins in tea and coffee - can they affect blood?

Having recently read articles on tannin in tea and coffee - such as nutritionist-org is there any information for people with combination of illnesses such as thyroid, diabetes, and anaemia to inform them of how much tea or coffee is safe to drink? As information suggests that tannins in tea affect the iron in the blood as much as 60% and coffee 50%, could the national favourites be responsible for poor healing, and anaemia?

Could tea drinking affect the use of anitbiotics? As tannins are present in beer,

could this affect the health of diabetics? Should there be an awareness campaign

of a possible culprit undermining heath?

20 Replies

Surely anyone eating or drinking too much of anything could harm one's health, not just because of tannins. What abour the health benefits of catechins in tea, coffee for mental aletness, & beer for sleep ~ it helps me! ;) There's a lot more tannin in red wine, also beneficial in moderation. Aren't diabetics told to limit their alcohol intake to 1-2 units a day, which would be about half a pint or a small glass of wine. Epigenetics would make these things harmful for some, & beneficial for others.

Perhaps people just need to be more informed about the interactions rather than scaremongered? Wheat also hinders iron absorption, unless it's sourdough, as does calcium rich food. I'm more concerned about agri-chemicals in my food & water, & the fact that white bread & all the various forms of artificial c**p that are passed off as food haven't been banned.

I drink lots of green tea & a huge coffee every day, sometimes beer & wine, but never within two hours of

my iron or any other supplements.


Don't know bout tannins but, I do know that tea contains fluoride and that interferes with the thyroids function - in Dr Peatfield's very informative book Your Thyroid and how to keep it healthy on page 16


Thanks for info - read a newspaper article saying that cheaper supermarket brands contain fluoride but branded tea such as typhoo and twinings don't have fluoride in them.


All tea?


It seems my choice of tea is quite safe:


I agree there are positives to tea and may be coffee, but for some people there may

be hiccups. I have cut out tannin in tea and coffee for the past week. Not only was my husband complaining that our mugs were brown stained, but also the loo - a black stained rim round the water. Since removing tannin from my diet, the cups, and loo are

clean. I have recently recovered from a cancerous mole being removed from my leg.

The wound was slow to heal. I am sure that the tannin in the tea I was drinking at least 5 times a day, was harming my iron levels. Since cutting it out, the wound has healed

better. I found the article written by Claire Reynolds

interesting as she says "tannin in both tea and coffee adversely affects iron availability

which could lead to iron deficiency anaemia".

She also says tea consumption may reduce iron absorption by as much as 60 percent

and coffee reduces its uptake by 50 percent. Apparently the thyroid gland may be

affected by fluoride in some teas mainly cheaper supermarket own brands.

I have been eating berries blackcurrants and raspberries damson plums and blue berries, and think they have helped metabolism.

Everyone is different and most people may not be affected at all - but I am not one

of the lucky ones so I am making an effort to lower my blood sugar, and help my immune system. I think there is a lot in what you say about wheat. It's the high processed shop bread, which is frozen, then put on shelves, which is only fit for

toast, which is starchy, and increases fat through starch stored in the liver as sugar

/glycogen. Wine too has tannins which might affect iron uptake in the blood -

orange juice is said to have the same good effects as wine, but without the tannin.

Thanks for updating me on information which you have found useful - I agree there is nothing worse than making a mountain out of a mole hill as far as food chat goes!

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Good news that you're getting better!

Were you drinking "builders' tea"? I use a glass teapot, & have to remember to put it in the dishwasher as it is never stained. I was given some cherry darjeeling, last year, & that didn't stain the pot or my glass teacups, either. I use a water filter, & think that makes a difference, as I change it when my tea stopps looking as bright. A good pot of green/white tea is one of my greatest pleasures, so one I would never give up! I just make sure not to drink it close to my THs or iron, the same with my daily coffee.

I read this last night: :)

I also wondered if the natural fluoride that's found in plants & water, is just as harmful as the industrially derived fluoride that's added to our water & toothpaste, etc? That's an unwanted chemical by-product, that industry wanted to sell, rather than dispose of, hence the fake correlation between better dental health in areas with naturally high fluoride in water.

You've given me a craving for damson jam on toast! :)


Sorry don't know about that the book reads - "Another common foodstuff to be thought about is, I am sorry to say, tea, since it contains significant levels of fluoride, which has a damaging effect on thyroid manufacture and tissue uptake".

Since reading this some 2 years a go I limit my tea to two cups per day and I think I have benefitted by doing so



Shame there are no guidelines - information suggests that tannin affects the blood by 60 percent, giving rise to anaemia and in coffee 50 percent. Didn't know about fluoride

until last week. Looking for fruit teas and tannin fluoride teas now! Thanks.


I meant tannin and fluoride free teas now..byee

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See my post, above!

Might be a good reason to get a nice Japanese cast iron pot for my sencha.

Pity my water filter doesn't remove fluoride.


Maxtra cartridges screen out most toxins an additives - Sometimes

I have to filter the same water several times so it tastes normal.

Does cast iron add to your iron count? Do aluminium kettles and

saucepans increase aluminium in water? What about copper saucepans - and Teflon? Interesting?


Not flouride, unfortinately. You must have very bad water, mine is ok with 1 filter.

Cast iron is supposed to get into food from cookware use. I haven't used aluminium for over 30 years, just in case. Teflon is bad, too. I'm sure we need copper?


I use stainless steel, and also a very expensive set of saucepans, with an indelible coating on them - so the blurb read - but one of my saucepans lost the coating with burning food..the others are ok though.

There are no warnings about coatings on pans- we all coast along, with no information concerning products

and water information - except for the discerning

buyers such as yourself!


Lots of information available in't'internet!


I thought there was fluride in water?


The amount of fluoride around the world varies hugely.

My local water has been analysed as having:

Fluoride (mg/l)

Standard 1.50

Number of samples 8

Compliance 100%

Minimum value 0.015

Maximum value 0.040

Average value 0.028

In England and Wales, you should be able to get hold of a recent analysis of your water quite readily. Not sure about Scotland and NI?


Does the level differ from each area? The additives in our water are placed in the system

not far from our home. The water is always cloudy when the additives are added.

It may take several days for the water to clear, which might indicate higher levels in areas

where the additives are placed.


The official figures relate to quite small areas - though they are bound to vary in size.

I have seen cloudy water when maintenance work has been performed. In my experience, if you leave it standing (e.g. in a glass jug) that sort of cloudiness will clear in an hour or two.

Occasionally the water companies raise the level of chlorine when there has been a problem. For example, if levels of bacteria have been too high, or it is suspected that contamination has occurred. With this issue, many people notice a smell of chlorine. Standing in a jug will clear the smell and any cloudiness but it can take much longer.

If you see cloudiness without it being one of the above, get in touch with your water supplier and ask them what is happening. They have a duty to supply decent water and substantial cloudiness is not acceptable.


Thank you. Have seen them put the stuff in but the amounts are unknown.

Had to filter my water three times yesterday, as I could taste the chemicals, in the water!


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