New study finds brewing tea may remove heavy metals from your water

A new study conducted by researchers from Northwestern University could have more consumers increasing their tea habit. 

The researchers discovered that brewing tea could be an effective way to remove heavy metals from your water. The study found that one mug of water with one tea bag that’s brewed for three to five minutes could reduce your lead intake by about 15%.  

“I’m not sure that there’s anything uniquely remarkable about tea leaves as a material,” Benjamin Shindel, the study’s first author, said in a news release “They have a high active surface area, which is a useful property for an adsorbent material and what makes tea leaves good at releasing flavor chemicals rapidly into your water. 

“But what is special is that tea happens to be the most consumed beverage in the world. You could crush up all kinds of materials to get a similar metal-remediating effect, but that wouldn’t necessarily be practical. With tea, people don’t need to do anything extra. Just put the leaves in your water and steep them, and they naturally remove metals.”

Putting tea to the test

To understand how brewing tea could affect the heavy metal composition of water, the researchers tested several different kinds of teas – black tea, white tea, green tea, oolong, chamomile, and rooibos. The teas were a mix of traditional tea bags and loose-leaf. 

The researchers then tested each of the teas in boiled water solutions that had different concentrations of heavy metals. They looked at lead, cadmium, chromium, copper, and zinc, all heavy metals that can pose a number of health risks to consumers. 

What happened?

While the researchers made several conclusions from their experiment, one was abundantly clear: the tea was effective at removing heavy metals from the water. 

One of the biggest findings was that the amount of time the tea spent brewing played a role in how effective it was at eliminating the metals. The more time the tea was steeping, the more contaminants it absorbed out of the water samples. 

“Any tea that steeps for longer or has higher surface area will effectively remediate more heavy metals,” Shindel said. “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.”

There were also differences depending on the type of tea, the type of tea bag, and more. 

The researchers found that cellulose tea bags – as opposed to cotton and nylon – were the most effective at absorbing the chemicals. The cotton and nylon bags had little to no effect on the metal concentration in the water, whereas the cellulose bags, which are most commonly used, produced the greatest purification effect. 

The study also showed that finely ground tea, rather than whole leaf tea, was better at absorbing the heavy metals. Additionally, black tea proved to yield the greatest metal absorption compared to other types of tea. 

“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 said in the news release. “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.”