Should You Be Concerned Over Fluoride In Green Tea

By Seppo | Diet

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There’s really no such thing as free lunch when it comes to health. For a long time I thought there are no downsides to drinking green tea. Until I learned that tea has a lot of fluoride, which of course can be toxic in high amounts.

So should you be concerned about fluoride in green tea? In this post we’ll look at how much fluoride there really is in green tea and whether that can cause any problems.

Case reports of fluoride toxicity from tea

Toxic fluoride exposure from tea is not just a theoretical concern. I found two case reports published in medical journals documenting this. However, in both cases the women had consumed a lot of tea.

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This one talks about a 49 year old woman who reported drinking 2 gallons of extra strength instant tea every day since she was 12 years old, so for 37 years. The tea as she prepared it had 5.8 mg/L of fluoride (including the fluoride in tap water). So she got about 35 mg per day from her tea, a way above recommended exposure limits.

In another case report a 48-year old woman reported drinking 1 – 2 gallons of brewed black tea per day. She bought the cheapest brand and used 7 twin bags per US gallon of water. The paper estimates that her tea had 3.87 mg/L of fluoride, which gives her total daily exposure of 14.6 – 36.9 mg – again far exceeding the limits.

But we have to consider these as extreme cases. Under normal circumstances tea doesn’t exposure you to dangerous amounts of fluoride.

How much fluoride is too much?

One of the most important principles of toxicology is the dose makes the poison. Almost any substance can be safely ingested in small enough quantities, and almost any substance can be harmful when ingested in large enough quantities.

And so it is with fluoride. In small doses it can protect the teeth, but in larger quantities it can be very dangerous. To assess whether fluoride in tea is a problem, we first have to understand how much fluoride can be safely ingested.

The World Health Organization summary statement on fluoride (PDF) sets 1.5 mg/L as guideline value for fluoride in drinking water. They also note that there’s suggestive evidence of risk when total intake exceeds 6 mg/day, and clear evidence of risk when total intake exceeds 14 mg/day.

National Academy of Sciences reviewed EPA’s standards on fluoride drinking water, and concluded that the maximum contaminant level of 4m g/L is too high. They didn’t advice on new limits, but noted that at concentrations of 2 mg/L only caused minor side effects, some dental discoloration in a small portion of the population.

Going by these two sources, I think it’s safe to use 6 mg/day as guideline for maximum fluoride exposure.

How much fluoride in a cup of tea?

Several studies have measured the amount of fluoride in tea.

A study from Hong Kong looked at the amount of fluoride in tea leaves from Guangdong Province in China. They found 0.6-2.8 mg/g in fallen tea leaves and 0.3-1 mg/g in young leaves. They also measured the amount in brewed tea, with the following results: 7.34 mg/L in brick tea, 1.89 mg/L in black tea and 1.6 mg/L in green tea. Brick tea is a low quality black, tea made from old, fallen tea leaves. This paper also noted that brewing tea extracted 24 – 83% of the total fluoride in tea leaves.

Another study looked at teas available in Turkey. It found 0.57 – 3.72 mg/L in black teas, and considerably less in herbal teas (0.02 – 0.04 mg/L). Unfortunately the study abstract didn’t mention anything about green tea.

A Polish study found 0.32 – 4.54 mg/L fluoride in black tea, 0.37 – 0.54 mg/L in white tea and 0.02 – 0.09 mg/L in herbal teas. This study looked at teas available in Brazil, and found 0.33 mg per bag of black tea and 0.08 mg/bag in green tea and 0.33 mg/bag in Oolong tea. If we convert those to mg/L we get 1.32 mg/L for black tea, 0.32 mg/L for green tea and 1.32 mg/L for Oolong tea.

I have a few more studies in the bag, but I don’t want to bore you by going over all of them. The results are more or less in line with what’s reported here. Based on these results it looks like most better quality black teas have less than 2 mg/L of fluoride. Most studies showed that green and white teas have less fluoride than black tea. Exactly how much is hard to say from such a limited dataset. Perhaps we can use 1.5 mg/L as off the cuff estimate, which is the drinking water guideline set by the World Health Organization.

Though, one researcher noted that the methods used in many studies actually underestimate the amount of fluoride. According to him, using better measurements shows 1.4 – 3.3 times higher fluoride levels. I did find two Chinese studies that showed quite a bit higher amounts per cup. At first I thought them as outlier studies, but it’s possible they used different measuring methods.

Other observations from the studies:

  • Lower quality teas have more fluoride than higher quality teas. That’s because lower quality teas are often made from fallen, old leaves that have more fluoride than young tea leaves. Lower quality teas may also use smaller tea leaves or ‘tea lead dust’, and studies have shown that the smaller the leaf size the more fluoride the tea contains. So you again get what you are pay for.
  • Decaffeinated tea showed higher fluoride values than caffeinated tea.
  • Ready to drink tea beverages probably have more fluoride than loose leaf and bagged tea, which makes sense as those are often brewed from low quality leaves.

Total fluoride exposure

Tea is probably not your only exposure to fluoride. Most states in the US have 0.7 – 1.2 mg/L of fluoride in tap water. In areas where’s there’s a lot of fluoride in the soil, this figure can be even higher. Check with your local authorities.

According to the National Academy of Sciences, tap water accounts for 57 – 90% of total exposure to fluoride for the average person. So for our purposes we can just focus on tea and tap water and ignore the other sources.

So let’s say that you live in an area that has 1 mg/L of fluoride in drinking water and drink 5 cups (about 1.2 L) of green tea per day, and that you drink an additional 2 L of water per day. 5 cups of tea would give you total of 3 mg of fluoride (1.2 L * 1.5 mg/L + 1.2 mg), and you would get a further 2 mg from the water you drink otherwise. That brings your total exposure to 5 mg per day.

You are still within our guideline value of 6 mg/day. The best evidence to date shows that might put you at a minor risk of dental discoloration, but that’s about it.

But what if those measurements underestimate the amount of fluoride in tea? This is a hard to say. But all epidemiological studies show health benefits from consuming 5 to 6 cups of green tea per day. I don’t remember any study mentioning higher risk from fluoride.

So I wouldn’t worry too much about fluoride in tea, especially if you go for better quality, loose leaf teas.

Conclusion

Tea contains naturally fairly high amounts of fluoride. The plant picks it up from the soil and brewing process extracts most of it from the leaves. However under normal circumstances this is probably not something to worry about.

Published case reports show cases of skeletal fluorosis from tea. But in all of these cases the people drank 1 – 2 gallons of low quality tea every day for decades. Studies looking at fluoride content in brewed tea show only moderate amounts content in higher quality teas. Lower quality and ready to drink tea beverages may have significantly more fluoride.

Quick calculations show that drinking 5 cups of tea still keeps you within safe exposure limits. But you should be careful if you live in an area with high amounts of natural fluoride in ground water.

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About the Author

Seppo Puusa, a.k.a. AcneEinstein shares rational advice about natural and alternative acne treatments. Read more about me and my acne struggles at the page.

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(10) comments

JH November 30, 2012

Thank you- your research into topics like this really is appreciated. As a high volume high quality organic green/white/herbal tea drinker (made with spring or purified water) I feel sort of safer, but to some degree it’s tough to tell what water sources are used for irrigation with any given crop… Especially from China. It’s crazy that I’ve taken my consumption to such extreme standards but still find some cause for concern! You can try so hard, yet rarely really ‘win’.

Reply
    Seppo November 30, 2012

    You may be suffering from a classic alt-med side-effect known as healthofobia :) I used to suffer from it also. Classic symptoms included always thinking there’s something wrong with you or that you could do more for your health.

    Jokes aside, I’m not sure how much of an issue fluoride is for other crops. The tea plant just seems to draw it out of the ground and that’s why it (and aluminium) is found in higher concentrations in tea leaves.

    If you already drink filtered or purified water I don’t think you need to be concerned over fluoride exposure from tea, and especially from a high quality green/white tea.

    We are always exposed to some chemicals and ‘toxins’, and the body is very good at eliminating them. And it has been that way for millions of years.

    Reply
Mike December 13, 2012

How interesting that reading through same research I came to conclusion that there’s too much F in my tea. I’m looking right now for ways of brewing that would limit the amount of F. If anyone knows of such studies please post. For example, I’m looking for full text of “Studies on the leaching of fluoride in tea infusions”. For quite informative summary about F: http://poisonfluoride.com/pfpc/html/green_tea___.html

Reply
    Seppo December 14, 2012

    I guess that depends on what do you mean by too much. I based my argument on two things. First there was the WHO report on toxicity of fluoride, and that showed little risk with exposure of 6 mg/day. Also, fluoride levels in most good quality green tea are still within or maybe little bit above of safety limits for drinking water. My other reason comes from epidemeological studies on green tea. I haven’t seen any mention in them that fluoride would cause problems for people drinking 5 to 6 cups per day.

    As you already mentioned in your other comment, the first brew absorbs most of the fluoride. The second brew has much less fluoride, and caffeine, but the problem is that the first brew also has the vast majority of the antioxidants. So you are getting less fluoride but also much less of the good stuff.

    BTW, if you are looking for full text articles the Google Scholar search is pretty good. DeepDyve is another good source. They are not free, but you can rent full-text papers for a dollar or two. http://www.deepdyve.com

    Reply
Mike December 13, 2012

F leaching in tea: http://www.academicjournals.org/ajpp/pdf/pdf2012/22%20May/Ma%20et%20al.pdf
It looks like it’s true that first infusion should go to your enemies :) and second to you and your friends…

Thank you, Chinese researchers, for publishing the study for free.

Reply
    Seppo December 14, 2012

    Looks like I had missed this paper. Thanks for bringing this up. Looks like the 2-brew method in this paper is a bit different than the one I saw in another paper. My comment about most of the antioxidant going to the first cup refer to making the first brew in hot water. As this paper noted, it might be a good idea to dip the leaves first into warm water for 20 seconds and then brew them in hot water.

    Reply
Mike December 14, 2012

The most interesting study I’ve found so far:
http://fst.sagepub.com/content/16/6/505.long

The two links I mentioned appear to backup your idea of infusing for 20 seconds (to get rid of fluoride) and drink second, 5-20 minute infusion for antioxidants.

Personally I’ve tried this method and I found that I like to remove tannin in the first step as well so I raised the temperature to 90degC. Of course method depends on tea and preferred taste.

There was an interesting mention in one paper (I don’t have a link to) that found fluoride release in Pu’erh tea to be 50% that of green or red tea (even though the amount of fluoride in such tea is higher, the release was somehow lower). Do you have an opinion on post-fermented tea? I just started looking into it and I find it fascinating there are so many varieties and depressing that there so little research :)

Reply
    Seppo December 15, 2012

    Oh, I’m sure the study you linked to supports my idea of 20 second first infusion to get rid of some fluoride – that’s where I got it from! :)

    I remember another paper talking about using 2 brews. They used longer time for the first infusion and showed that a lot of the fluoride and antioxidants were absorbed into the first cup.

    I covered how different brewing conditions affect green tea catechin content in my first tea hacking post. I also wrote another post that dealt with stability and absorption of green tea catechins.

    I can’t comment on Pu’erh tea. I’m mainly interested in fluoride in green tea because in other posts I recommend acne patients to drink at least a few cups a day.

    Reply
Tony Valdes May 1, 2013

Hey here’s a company that sells a green tea with no pesticides or fertilizers and is watered with spring water (should eliminate fluoride). http://verdanttea.com/teas/mrs-lis-shi-feng-dragonwell-green-tea/ Here is another article about this tea and the village it’s grown in. http://verdanttea.com/dragonwell-village-visiting-mrs-lis-shifeng-tea-fields/

Reply
    Seppo May 1, 2013

    The tea plant picks up fluoride from the ground. So the most important factor in fluoride content of finished tea is the fluoride content of the soil the tea was grown in. I doubt that using spring water to water the tea plants has much of an effect on how much fluoride the tea plants pick up. It’s useful as a marketing slogan, but I’m not sure it makes any practical difference to the quality of the product.

    Reply
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