Numerous studies have shown tea’s many health benefits. Here’s another: Brewed tea can filter and remove harmful heavy metals, including lead, Northwestern University researchers in Evanston recently discovered.
Brewing black, green, white or oolong tea can trap the metals as the tea leaves act like a sponge.
“We all wondered if in addition to releasing wonderful flavor and other contents from the tea leaves, if tea leaves and bags encasing the leaves would in turn capture dissolved toxins,” says Vinayak Dravid, Northwestern professor of materials science and engineering and senior author of the study.
While the findings may be comforting to U.S. tea drinkers, it’s particularly important to those people living around the world exposed to highly contaminated water.
Dravid says his research group and a startup company he co-founded called Coral Innovations have already been developing a “sponge-based cleaning approach” to wastewater that is somewhat similar to brewing tea. The company aims to clean other bodies of water, too, including those contaminated from oil spills.
As for the cup of tea as a small environmental cleaning agent, Dravid says this research can help people across the U.S. and the world, especially those who live in areas where there is little to no government cleanup of water that is contaminated with lead, cadmium, chromium, copper, zinc or any other metal that can damage the brain or vital organs. Heavy metals pose a number of health risks.
“In resource-limited situations, perhaps cleaning one glass at a time is likely to be more effective with immediate and lasting impact,” Dravid says.
The study team was led by Dravid’s former doctoral student Benjamin Shindel, who is now a contractor with the U.S. Department of Energy.
It was Shindel’s idea to test the tea bags as a small-scale experiment that may someday translate to larger industrial cleanups of pollution.
“Our approach is to find nanoscale solutions to giga-ton problems of environmental pollution,” Dravid says.
The research was published Monday in ACS Food Science & Technology, a journal of the Washington-based American Chemical Society.
The researchers experimented with different types of tea and bags and brewing methods.
They looked at loose-leaf brewed tea, for instance.
“Just put the leaves in your water and steep them and they naturally remove metals,” Shindel says.
And they looked at tea brewed with bags.
One caveat is to use cellulose paper-like tea bags rather than those made with nylon, which are already a problem for the environment because they release microplastics.
Like nylon, cotton tea bags also are ineffective, removing practically no metals, according to the researchers.
