Brewing tea can remove a significant amount of toxic heavy metals from drinking water, according to a new study.
The study – published Feb. 24 in the journal ACS Food Science & Technology — analyzed how different types of tea, tea bags and brewing methods affect heavy metal adsorption. These included “true” teas such as black, green, oolong and white, as well as chamomile and rooibos teas.
Researchers also looked at the differences between loose-leaf and commercially bagged tea.
Scientists from Northwestern University, who conducted the study, found that tea leaves naturally absorb heavy metals, filtering dangerous contaminants from water like lead and cadmium. Heavy metal ions stick to the surface of the tea leaves, where they stay trapped.
“You’re taking the metals out of the water with the tea, but you don’t consume the tea leaves after, which is why it works,” Benjamin Shindel, the study’s lead author, told the Washington Post.
The study also noted that the longer the steeping time, the more contaminants were adsorbed.
“Any tea that steeps for longer or has higher surface area will effectively remediate more heavy metals,” Shindel said in a release. “Some people brew their tea for a matter of seconds, and they are not going to get a lot of remediation. But brewing tea for longer periods or even overnight — like iced tea — will recover most of the metal or maybe even close to all of the metal in the water.”
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Researchers estimate that tea preparation can remediate about 15% of lead from drinking water, even up to lead concentrations as high as 10 parts per million.
“Across a population, if people drink an extra cup of tea per day, maybe over time we’d see declines in illnesses that are closely correlated with exposure to heavy metals,” Shindel added. “Or it could help explain why populations that drink more tea may have lower incidence rates of heart disease and stroke than populations that have lower tea consumption.”
Other research has also found potential health benefits of drinking tea.
In a study reviewed in the journal of the American Cancer Society, researchers found that people who drink less than a cup of tea had a 9% lower chance of developing head or neck cancer.
The study also noted that those who drank less than a cup of tea had a lower chance of developing hypopharyngeal cancer — which develops in the bottom part of the throat, per John Hopkins Medicine.
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