Scientists tested the content of disinfection byproduct (DBP) exposure in tea that was brewed with drinking water or boiled water.
The levels of these compounds in the drink were lower than in the water itself, but most of them were unknown to researchers – as well as their effects on human health.
Tea is the second most consumed beverage in the world after water. For millennia in the East, it has been considered the key to health, wealth, and even wisdom. Subsequently, tea became popular in the West, and experts are still discovering its beneficial properties.
Several varieties of this plant, Camellia sinensis, have been shown to help with cancer, heart disease and diabetes, as well as lower cholesterol, promote weight loss, and improve cognitive function. In addition, tea has antimicrobial properties.
To brew a drink, in most cases, boiled tap water is needed, but there is a moderate amount of chlorine in it, and in this case, its residues can react with tea compounds – including polyphenols, amino acids, caffeine, and so on. As a result, disinfection by-products (DBP) are formed, which are often mutagenic and carcinogenic in nature and cause adverse reproductive effects.
Chemists and biochemists from the University of South Carolina in Columbia, USA, using gas chromatography-mass spectrometry, revealed 60 PPDs in green and black teas of three brands (Twinings, Earl Gray and Lipton).
It turned out that their levels in brewed tea are lower than in tap water, due to volatilization and absorption by the leaves. But many unknown compounds (96 percent of the total) were also found in the drink, beloved by many, the effect of which on human health is not yet known.
The results of the work were published in the journal Environmental Science & Technology.
Fifteen previously undescribed halogenated aromatic compounds were identified: according to scientists, they are formed as a result of the reaction of chlorine with polyphenols in tea.
Green, black and yellow tea leaves are rich in phenolic compounds, which are known for their antioxidant activity and beneficial effects on human health.
Among tea polyphenols, catechins, flavonols, anthocyanidins and phenolic acids are distinguished.
“Further research will be required to identify unknown compounds, since halogenated aromatic PPDs can be highly toxic,” warned the authors of the work.
For most disinfection by-products, the maximum permissible levels have not yet been established by experts.
However, some have been studied enough: to stay in the “safe zone”, it is recommended not to drink more than 18-55 cups of brewed tea per day.
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