Tea leaves pull heavy metals from water, considerably decreasing the quantity of lead and different harmful compounds that folks could also be unknowingly consuming, a brand new examine discovered.
Current analysis has highlighted potential purposes for used tea leaves, from biofuels to gluten-free cookies. However the brand new examine exhibits a public well being profit from one thing that numerous individuals are already doing. About 5 billion cups of tea are consumed every day around the globe, based on one estimate.
“You’ll be able to see the implications,” stated Vinayak Dravid, a supplies scientist at Northwestern and an creator of the examine, which was revealed this week. “How usually can we contact billions of individuals?”
In lots of international locations, the water used to steep tea is contaminated with lead from getting older pipes. In the USA, 9 million houses get their water by means of pipes that include lead, based on the Environmental Safety Company. Lead is very harmful to kids. Publicity can result in developmental delays and behavioral points.
Dr. Dravid and his crew examined how several types of tea — black, white, oolong, inexperienced, rooibos, natural, unfastened leaf and plain outdated Lipton — behaved in water with various quantities of lead.
The tea was then allowed to steep for variable durations of time. Afterward, the scientists measured how a lot lead remained within the water.
Compounds known as catechins in tea leaves act like “little Velcro” hooks to which lead molecules latch, stated Michelle Francl, a chemist at Bryn Mawr Faculty and the creator of a e book on the chemistry of tea. Dr. Francl additionally stated that the “ridges and valleys” of the tea leaves supplied the mandatory floor space for that interplay.
Whereas these properties have been identified for a while, Dr. Dravid and his colleagues have been the primary to have a look at the lead-detoxifying powers of a single cup of tea. They discovered that black tea leaves turned wrinkled after roasting and have been thus greatest geared up to soak up heavy metals.
“Inexperienced tea and black tea had pretty equal quantities of metallic absorbed,” stated one other creator, Benjamin Shindel, who was a doctoral candidate at Northwestern whereas engaged on the examine.
White tea, however, undergoes a way more light preparation. Its leaves stay clean, providing much less floor space from which to attract heavy metals from water. Natural tea fans could also be disenchanted to study that chamomile tea does a poor job of heavy-metal filtering, too, most likely as a result of it’s made with chamomile flowers, not tea leaves.
Nonetheless, these distinctions between several types of tea weren’t essentially the most related issue. “It’s rather more essential how lengthy you’re brewing the tea for,” Dr. Shindel stated.
The researchers discovered that steeping a cup of black tea for 5 minutes might take away 15 % of lead from the water, which is useful, however there may be “no secure stage” of lead publicity, based on the E.P.A.
“With lead and different contaminants, any lower is significant to some extent, particularly when you have an absence of assets or infrastructure that may already remediate a few of these drawback supplies,” stated Caroline Harms, who was an undergraduate scholar of Dr. Dravid at Northwestern whereas engaged on the examine.
The longer the steeping time, nevertheless, the extra bitter the ensuing tea. Final yr, Dr. Francl prompted a minor worldwide scandal by suggesting that including salt to tea might mitigate its bitterness. However even that controversial chemistry hack has its limits. “It’s not likely drinkable after 10 minutes of steeping tea, and no quantity of salt goes to assist that,” she stated.
Some samples within the examine needed to be steeped for twenty-four hours, which might render the tea undrinkable.
The examine’s authors stated they have been much less motivated to make public well being prescriptions for policymakers than to review a hidden advantage of a worldwide behavior.
The researchers estimated {that a} nation the place folks drank giant quantities of tea would have about 3 % much less lead ingestion from the water provide than a (hypothetical) similar nation that didn’t drink any tea.
“How great,” stated Henrietta Lovell, the founding father of the Uncommon Tea Firm. Ms. Lovell, who provides teas to unique eating places, identified that tea had been utilized in China for medicinal functions for hundreds of years. “The extra I study tea, the extra fabulous and interesting it turns into,” Ms. Lovell stated.
Dr. Francl believes that the brand new findings might ultimately pave the best way to a scalable methodology of constructing certain folks aren’t ingesting heavy metals. “Provided that clear water is such a worldwide difficulty,” she stated, “if there was a strategy to take this proof of idea and tweak it to supply potable water on the finish, that may be fairly good.”
