(Originally posted on bcotoronto.com on Jan 31st, 2013)
On Tuesday we posted an article on our Facebook page about the natural levels of Fluoride in tea. This is every concerning for me as a healthcare professional who recommends green tea to patients and as an avid tea drinker. So I wanted to take some time this week and explore this issue.
It turns out that the tea plant naturally absorbs sodium fluoride and aluminum from the soil it is in and this carries into the water while it is steeping1-5. This is a concern because fluoride is toxic6-9 and aluminum has been strongly associated with the development of Alzheimer’s disease in the research10-12.
Fluoride has been categorized as an essential nutrient for more than half a century because it promotes bone and teeth mineralization. Despite this there is a growing movement among health professionals to stop the fluoridation of municipal drinking water13 for many different reasons. Fluoride has been shown to cause oxidative stress6-9 throughout the body with a proposed mechanism of down regulating natural antioxidant production6. The effects of fluoride toxicity are most commonly experienced in the nervous system, muscles, kidneys, and bones14.
Fluoride is found in our food supply in meats, leafy green veggies, and legumes which we absorb anywhere from 50-80% of but in the form it is found in our water supply and toothpaste, and in the form in tea plants (Sodium Fluoride) it is absorbed 100%.
According to the Linus Pauling Institute an average cup of green or black tea contains 0.2-0.5mg of sodium fluoride in every 8 ounce cup1. This is more than our average Canadian drinking water15-17. It would take 8 cups of tea in a day to reach the RDA of 3-4mg/day and 20 cups to reach a high enough level to kill you (TUI 10mg/day). This is, of course, assuming you make your tea with filtered water and not tap water which would add to the amount but still take quite a bit to become truly harmful. As well, several studies have shown that supplementation with anti-oxidants can minimize and toxic effects that fluoride may have7-9 as will exercise6. In this way I suggest that that the fluoride in tea is not something we need to be worried about.
Aluminum, on the other hand, is not an essential nutrient and has been associated with the development of Alzheimer’s disease10-12. Aluminum build-up in the tissues of the brain will cause decreased cognitive ability and loss of memory. There is very little to suggest that this can be reversed or avoided other than limiting exposure.
So why drink tea at all if it has toxic components? Well, as in all things in medicine, and many other professions, it is all about the ratio of risk to benefit. There is quite a bit of research out there which has linked green tea, and sometimes black tea as well, with decreased rates of heart attack, stroke, cancer, and osteoporosis1 as well as increased memory and cognitive functioning18-20. So despite having aluminum content green tea actually has a “neuroprotective”18 quality which outweighs the neurodegenerative nature of aluminum or the oxidative stress of fluoride.
In the end, tea has a much higher BENEFIT than its RISK, so I’m definitely not going to stop recommending it to my patients and not going to stop drinking it myself. What do you think about it?
Thanks for reading,
1. http://lpi.oregonstate.edu/infocenter/phytochemicals/tea/ (Accessed 01/28/13)
7. Nabavi SF, Habtemariam S, Jafari M, Sureda A, and Nabavi SM. Protective role of gallic acid on sodium fluoride induced oxidative stress in rat brain. Bulletin of Environmental Contamination and Toxicology 2012;89(1):73-77
10. Jiang T, Zhi XL, Zhang YH, Pan LF, and Zhou P. Inhibitory effect of curcumin on the Al(III)-induced Aβ₄₂ aggregation and neurotoxicity in vitro. Biochimica et Biophysica Acta 2012;1822(8):1207-1215
11. Zhang QL, Jia L, Jiao X, Guo WL, Ji JW, Yang HL, and Niu Q. APP/PS1 transgenic mice treated with aluminum: an update of Alzheimer’s disease model. International Journal of Immunopathology and Pharmacology 2012;25(1):49-58
13. http://www.yes4cleanwater.org/Documents/CoutriesRejectedF.pdf (accessed 01-29-13)
15. http://en.wikipedia.org/wiki/Fluoridation_by_country#Canada (accessed 01-29-13)
16. http://www.toronto.ca/health/dental/pdf/fluoride.pdf (accessed 01-29-13)
17.http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/2008-fluoride-fluorure/index-eng.php (accessed 01-29-13)
18. Biasibetti R, Tramontina AC, Costa AP, Dutra MF, Quincozes-Santos A, Nardin P, Bernardi CL, Wartchow KM, Lunardi PS, and Gonçalves CA. Green tea (-)epigallocatechin-3-gallate reverses oxidative stress and reduces acetylcholinesterase activity in a streptozotocin-induced model of dementia. Behavioural Brain Research 2013;236(1):186-193
19. Borgwardt S, Hammann F, Scheffler K, Kreuter M, Drewe J, and Beglinger C. Neural effects of green tea extract on dorsolateral prefrontal cortex. European Journal of Clinical Nutrition 2012;66(11):1187-1192
20. Wang Y, Li M, Xu X, Song M, Tao H, Bai Y. Green tea epigallocatechin-3-gallate (EGCG) promotes neural progenitor cell proliferation and sonic hedgehog pathway activation during adult hippocampal neurogenesis. Molecular Nutrition and Food Research 2012;56(8):1292-1303