Green Tea | important medical contraindications by Lynn Daniluk (Guest Author)

healthy living May 14, 2018

What I have posted here is a bit controversial. A while back, my sister was doing some research on green tea and she came across a study that alarmed her. Her husband often drank large quantities of green tea each day so, she continued her research and presented me with her findings. I was shocked and her husband immediately stopped drinking black and green tea altogether!

Like most nutritionists, I have been recommending the use of green tea for years.  I present this article, written by my sister, Lynn Daniluk, for your consideration, to help you assess if you are one of the population for which green tea is not beneficial.

I have modified my tea recommendations and suggest that, if you suffer from certain medical conditions, such as thyroid dysfunction or osteoarthritis, you, too, may not benefit from this age-old beverage.

Sodium Flouride in Black & Green Tea

by Lynn Daniluk

If you are unwilling to drink a glass of fluoridated water from a city tap, then you should think twice about drinking green or black tea (Camellia sinensis).

According to the City of Ottawa website,

"In September 2009, the City of Ottawa reduced the target level of fluoride in drinking water to 0.70 mg/L in response to the new level recommended by Health Canada. These changes were made under the direction of the Medical Officer of Health."1

According to the calculations made by the Oregon State University's Linus Pauling Institute Micronutrient Research Centre2, all tea has a higher level of sodium fluoride than the City of Ottawa's fluoridated drinking water. The levels per litre depend on the length of time the tea is steeped – even a 5-minute brew will give you a higher level than Ottawa's City water.

These calculations were made from tea that was brewed using water that was not fluoridated, so the fluoride levels when using fluoridated water would be compounded. It's important to note that the Linus Pauling Institute (LPI) website doesn't state any problem with fluoridation – it's felt that fluoride prevents tooth decay, so LPI would not be trying to reduce the numbers in order to make the situation look better. Besides, these levels have been confirmed by other studies done in China, Turkey7 and India.

Sodium Fluoride Content of Teas*

Green                1.2-1.7            mg/L

Oolong              0.6-1.0            mg/L

Black                1.0-1.9             mg/L

Brick tea           2.2-7.3             mg/L  

*Fluoride in 1% weight/volume tea prepared by continuous infusion from 5 to 360 minutes

It's interesting to note that the initial level of fluoride in green tea is higher than black tea, so the concept that green is universally better than black does not hold water.

My next concern is the level of aluminum in tea which compounds the effects of sodium fluoride.

Once you start to look at the studies, you'll realize that scientists are talking about aluminum and fluoride together in the same sentence.3 4 This has far-reaching implications that go beyond the idea that a bit of fluoride helps tooth enamel.

It is also important to not overlook the effects of caffeine on the uptake of sodium fluoride.

In their online drug reference manual, Pharmacokinetics, the Medscape website states, "some studies suggested that oral bioavailability of fluoride may increase with concomitant administration of caffeine".5 While it appears that caffeine can increase the absorption rate of sodium fluoride in your body, decaffeination does not solve this problem. One study showed how the process of decaffeination actually increased the level of sodium fluoride in the tea.6

A 2009 study, conducted in Turkey, showed that "herbal and fruit infusions were characterized by low values of fluoride (0.02–0.04 mg/L) after 5 minutes of brewing and increasing brewing time to 10 minutes caused only slight increases in some infusions".7 Tea grown in the same area had a very large amount of fluoride by comparison.

It appears that the tea plant has the specific ability to absorb sodium fluoride and aluminum from the environment that other plants do not possess.

It does not matter what is put on the plant in the way of pesticides, herbicides or fertilizer, the plant collects these toxic minerals from the soil and water. In other words, drinking organic tea may not be helpful in this case. It is also hard to know what constitutes 'organic' in places such as China, Turkey, Sri Lanka, India and Kenya. Though the tea plants may not be sprayed with pesticides and herbicides, the soil and water the plants grow in are often contaminated.

According to Dr. Michael P. Whyte, Professor of Medicine, Pediatrics & Genetics and Medical-Scientific Director, Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children, St. Louis, "the tea plant is known to accumulate fluoride from the soil and water".8

Dr. Whyte is the same doctor who conducted the study on Skeletal Fluorosis and green & black tea,9 "Says Dr. Whyte, "When fluoride gets into your bones, it stays there for years, and there is no established treatment for skeletal fluorosis. No one knows if you can fully recover from it." In other words, fluoride accumulates in your body".8

It is known that fluoride has an effect on thyroid function.

After reviewing the evidence, I suggest that if you suffer from thyroid issues, consider limiting your use of green tea and green tea products. For more information, check out this particularly well-written article, Green Tea, Fluoride & the Thyroid.

The author of this article cites, "a major Canadian study published in 1995 reports average fluoride content in tea to be 4.57 mg/l in the 1980s".10 I checked the Health Canada website, confirming that Health Canada not only knew about the study, they funded it.

Considering the millions of tonnes of tea consumed worldwide every year, there is plenty of reason to keep the myth of tea's health benefits alive.

There's also no doubt that there are some beneficial compounds within the tea plant... though at what cost to your body?


  1. The City of Ottawa's Fluoride Facts
  2. Oregon State University's "Linus Pauling Institute Micronutrient Research Centre"
  3. Aluminium and fluoride contents of tea, with emphasis on brick tea and their health implications H. Wong Corresponding Author Contact Information, E-mail The Corresponding Author, K. F. Fung and H. P. Carr. Department of Biology, Institute for Natural Resources and Environmental Management, Hong Kong Baptist University, Kowloon Tong, Hong Kong. 21 December 2002.
  4. Fluoride and aluminium concentrations of tea plants and tea products from Sichuan Province, PR China W. S. Shua, Z. Q. Zhanga, C. Y. Lana and M. H. WongCorresponding Author Contact Information, a) State Key Laboratory for Bio-control, School of Life Sciences, Zhongshan University, Guangzhou 510275, People’s Republic of China. b) Institute for Natural Resources and Environmental Management, and Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, People’s Republic of China. 19 June 2003.
  5. Medscape: On-line Drug Reference Manual: Pharmacokinetics
  6. Fluoride Content in Caffeinated, Decaffeinated and Herbal Teas J.T. Chana, S.H. Kohb Vol. 30, No. 1, 1996 a) Department of Basic Sciences and b) Department of General Dentistry, University of Texas Dental Branch, University of Texas Houston Health Science Center, Houston, Tex., USA. Caries Research (1996) 30:88-92 The average sodium fluoride concentration of infusions prepared from decaffeinated (green & black) tea were found to be 3.19 ppm and ranged from 1.01 to 5.20.
  7. Fluoride levels in various black tea, herbal and fruit infusions consumed in Turkey Ebru Emekli-Alturfana,*, Aysen Yarata, Serap Akyuzb. a) Department of Biochemistry, Faculty of Dentistry, Marmara University, Nisantasi, 34365 Istanbul, Turkey. b) Department of Pedodontics, Faculty of Dentistry, Marmara University, Nisantasi, 34365 Istanbul, Turkey 16 January 2009
  8. Why Green Tea Would be Healthy EXCEPT for This One Dangerous Issue by
  9. Skeletal Fluorosis from Instant Tea Whyte MP, Totty WG, Lim VT, Whitford GM. 2008 May;23(5):759-69. Division of Bone and Mineral Diseases, Washington University School of Medicine at Barnes-Jewish Hospital, St Louis, Missouri, USA.
  10. Survey of lead, cadmium, fluoride, nickel, and cobalt in food composites and estimation of dietary intakes of these elements by Canadians in 1986-1988 Dabeka, R.W. (Health and Welfare Canada, Ottawa, ON, Canada.); McKenzie, A.D. Journal of AOAC International (USA)

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