Editing Fluoride (section)

=== Biochemistry ===
At physiological pHs, [[hydrogen fluoride]] is usually fully ionised to fluoride. In [[biochemistry]], fluoride and hydrogen fluoride are equivalent. Fluorine, in the form of fluoride, is considered to be a [[micronutrient]] for human health, necessary to prevent dental cavities, and to promote healthy bone growth.<ref name="who.int">{{cite web|last1=Fawell|first1=J. |title=Fluoride in Drinking-water|url=https://www.who.int/water_sanitation_health/dwq/chemicals/fluoride.pdf|publisher=World Health Organization|access-date=10 March 2016}}</ref> The tea plant (''[[Camellia sinensis]]'' L.) is a known accumulator of fluorine compounds, released upon forming infusions such as the common beverage. The fluorine compounds decompose into products including fluoride ions. Fluoride is the most bioavailable form of fluorine, and as such, tea is potentially a vehicle for fluoride dosing.<ref name=Chan2013>{{Cite journal|last=Chan|first=Laura|author2=Mehra, Aradhana |author3=Saikat, Sohel |author4= Lynch, Paul |title=Human exposure assessment of fluoride from tea (''Camellia sinensis'' L.): A UK based issue?|journal=Food Research International|date=May 2013|volume=51|issue=2|pages=564–570|doi=10.1016/j.foodres.2013.01.025}}</ref> Approximately, 50% of absorbed fluoride is excreted renally with a twenty-four-hour period. The remainder can be retained in the oral cavity, and lower digestive tract. Fasting dramatically increases the rate of fluoride absorption to near 100%, from a 60% to 80% when taken with food.<ref name=Chan2013 /> Per a 2013 study, it was found that consumption of one litre of tea a day, can potentially supply the daily recommended intake of 4&nbsp;mg per day. Some lower quality brands can supply up to a 120% of this amount. Fasting can increase this to 150%. The study indicates that tea drinking communities are at an increased risk of [[dental fluorosis|dental]] and [[skeletal fluorosis]], in the case where water fluoridation is in effect.<ref name=Chan2013 /> Fluoride ion in low doses in the mouth reduces tooth decay.<ref>{{Cite web | url=http://oradyne.net/fluoride-free-toothpaste/ | title=Fluoride Free Toothpaste – Fluoride (Finally!) Explained| date=2016-06-27}}</ref> For this reason, it is used in toothpaste and water fluoridation. At much higher doses and frequent exposure, fluoride causes health complications and can be toxic.