{"id":8677,"date":"2012-11-27T06:40:33","date_gmt":"2012-11-27T06:40:33","guid":{"rendered":"https:\/\/acneeinstein.com\/?p=766"},"modified":"2018-11-03T12:09:11","modified_gmt":"2018-11-03T12:09:11","slug":"fluoride-green-tea-concern","status":"publish","type":"post","link":"https:\/\/acneeinstein.com\/fluoride-green-tea-concern\/","title":{"rendered":"Should You Be Concerned Over Fluoride In Green Tea"},"content":{"rendered":"

There\u2019s 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.<\/p>\n

So should you be concerned about fluoride in green tea? In this post we\u2019ll look at how much fluoride there really is in green tea and whether that can cause any problems.<\/p>\n

Case reports of fluoride toxicity from tea<\/h2>\n

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.<\/p>\n

This one<\/a> 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.<\/p>\n

In another case report<\/a> a 48-year old woman reported drinking 1 \u2013 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 \u2013 36.9 mg \u2013 again far exceeding the limits.<\/p>\n

But we have to consider these as extreme cases. Under normal circumstances tea doesn\u2019t exposure you to dangerous amounts of fluoride.<\/p>\n

How much fluoride is too much?<\/h2>\n

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

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.<\/p>\n

The World Health Organization summary statement on fluoride<\/a> (PDF) sets 1.5 mg\/L as guideline value for fluoride in drinking water. They also note that there\u2019s suggestive evidence of risk when total intake exceeds 6 mg\/day, and clear evidence of risk when total intake exceeds 14 mg\/day.<\/p>\n

National Academy of Sciences reviewed EPA\u2019s standards on fluoride drinking water<\/a>, and concluded that the maximum contaminant level of 4m g\/L is too high. They didn\u2019t 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.<\/p>\n

Going by these two sources, I think it\u2019s safe to use 6 mg\/day as guideline for maximum fluoride exposure.<\/p>\n

How much fluoride in a cup of tea?<\/h2>\n

Several studies have measured the amount of fluoride in tea.<\/p>\n

A study from Hong Kong<\/a> 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 \u2013 83% of the total fluoride in tea leaves.<\/p>\n

Another study<\/a> looked at teas available in Turkey. It found 0.57 \u2013 3.72 mg\/L in black teas, and considerably less in herbal teas (0.02 \u2013 0.04 mg\/L). Unfortunately the study abstract didn\u2019t mention anything about green tea.<\/p>\n

A Polish study<\/a> found 0.32 \u2013 4.54 mg\/L fluoride in black tea, 0.37 \u2013 0.54 mg\/L in white tea and 0.02 \u2013 0.09 mg\/L in herbal teas. This study<\/a> 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.<\/p>\n

I have a few more studies in the bag, but I don\u2019t want to bore you by going over all of them. The results are more or less in line with what\u2019s 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.<\/p>\n

Though, one researcher noted that the methods used in many studies actually underestimate the amount of fluoride<\/a>. According to him, using better measurements shows 1.4 \u2013 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\u2019s possible they used different measuring methods.<\/p>\n

Other observations from the studies:<\/p>\n