FRIDAY, March 7, 2025 (HealthDay News) -- Your daily cup of tea might do more than help you relax -- it could also help remove harmful heavy metals from your drinking water, new research suggests.
A Northwestern University study found that tea leaves can naturally pull lead and other dangerous metals out of water as tea steeps.
About 5 billion cups of tea are consumed each day worldwide, according to one estimate.
“You can see the implications,” said Vinayak Dravid, a materials scientist at Northwestern and an author of the study. “How often do we touch billions of people?”
Heavy metal contamination -- especially lead -- is a growing concern, especially in areas with aging pipes.
The U.S. Environmental Protection Agency (EPA) estimates that about 9 million U.S. homes get their water through pipes that contain lead, The New York Times reported. Those pipes can allow the toxic metal to leach into drinking water.
Even small amounts of lead exposure can be dangerous, especially for children, potentially leading to developmental delays and behavioral problems.
In the study, David and his team tested a variety of teas -- including black, white, oolong, green, rooibos, herbal, loose leaf and plain Lipton -- to see how well they absorbed lead from water during various steeping times.
The researchers found that black tea was the most effective at pulling lead from water.
“Green tea and black tea had fairly equivalent amounts of metal absorbed,” co-author Benjamin Shindel told The Times. He worked on the study as a doctoral candidate at Northwestern.
This is because compounds called catechins act like “little Velcro” hooks to which lead molecules latch, Michelle Francl, a chemist at Bryn Mawr College, explained.
Francl added that tea leaves also have a rough surface with "ridges and valleys," which provides more space for metals to attach to them.
White tea, which is more gently processed and has smoother leaves, absorbed far less lead.
Herbal teas like chamomile, which aren’t made from actual tea leaves, were also less effective.
Steeping black tea for five minutes removed about 15% of the lead from the water. And while any reduction is helpful, the EPA warns that no amount of lead exposure is safe.
“With lead and other contaminants, any decrease is meaningful to some extent, especially if you have a lack of resources or infrastructure that would already remediate some of these problem materials,” said Caroline Harms, who worked on the study as an undergraduate student of Dravid's at Northwestern.
While longer steeping times did pull out more lead, they also made the tea more bitter.
“It’s not really drinkable after 10 minutes of steeping tea, and no amount of salt is going to help that,” Francl told The Times.
Some samples steeped for 24 hours removed the most metals, but they would be impossible to drink.
Researchers estimated that in countries where tea drinking is common, people could be ingesting about 3% less lead from their water compared to their counterparts in countries that don’t drink tea.
“Given that clean water is such a global issue,” Francl concluded, “if there was a way to take this proof of concept and tweak it to produce potable water at the end, that would be pretty good.”
The findings were recently published in ACS Food Science & Technology.
More information
The U.S. Centers for Disease Control and Prevention has more about lead in drinking water.
SOURCE: The New York Times, Feb. 28, 2025