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Friday, March 17, 2017

Human exposure assessment of fluoride from tea (Camellia sinensis L.)



Fluoride concentrations in UK tea, including the leading supermarket economy labelled products, were determined. Fluoride ranged from 93 to 820 mg/kg in the products and 0.43 to 8.85 mg/L in the infusions. The UK supermarket economy teas contained elevated fluoride, ranging from 3.60 to 7.96 mg/L in a 2 minute brewing infusion, comparable to Chinese brick tea, indicating the use of mature leaves in their manufacture. Considering the dietary reference intake (DRI) of 4 mg/day of fluoride for an adult consuming 1 L of tea, prepared from an economy tea, containing 6.0 mg/L fluoride, 75–120% of the DRI fluoride is available for absorption by the human system in the presence of food, increasing to 150% when fasting. Excess fluoride in the diet can lead to detrimental health effects such as fluorosis of the teeth and skeletal fluorosis and consuming economy branded tea will lead to exposure.


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Overall, for the tea products as a whole data set, increasing fluoride is released into a tea infusion with time. For the individual tea groups, the 2 minute infusion contained significantly lower fluoride compared to the longer infusion times of 10 and 30 min. Most of the fluoride was released into the tea infusion after 10 min with no significant differences between 10 and 30 min (p ≥ 0.09). This fluoride is available for absorption by the human system and can partly or completely fulfil the recommended DRI of 4 mg/day for an adult. Detrimental health effects such as fluorisis of the teeth or in the extreme calcification and osteoporosis, indicative of skeletal fluorosis could occur when an adult consumes 1 L of tea daily, especially when prepared using a UK supermarket Economy brand. However, if consuming other tea varieties, such as Oolong/Pu'er, Assam, Ceylon or Darjeeling, then exposure to fluoride is significantly lower.

Tea is a globally popular beverage, for which there are studies suggesting many beneficial health effects from some components in tea, such as anti-oxidants. Benefits should be contrasted with potential detrimental health effects from fluoride extracted from tea. However all tea products should be considered as a main source of fluoride in the diet. Supermarkets and manufacturers of tea should consider stating fluoride concentration as part of the nutritional information found on food packaging.

http://www.sciencedirect.com/science/article/pii/S0963996913000446

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