A recent study by Northwestern University reveals that brewing tea can naturally remove heavy metals like lead from water, offering significant public health benefits.
Researchers at Northwestern University have unveiled a remarkable discovery that could delight tea drinkers and public health advocates alike. According to a study published today in ACS Food Science & Technology, brewing tea can effectively adsorb heavy metals such as lead and cadmium from water, thus acting as a natural filter for these dangerous contaminants.
“For this study, our goal was to measure tea’s ability to adsorb heavy metals. By quantifying this effect, our work highlights the unrecognized potential for tea consumption to passively contribute to reduced heavy metal exposure in populations worldwide,” senior author Vinayak Dravid, an expert on sorbent materials and Abraham Harris Professor of Materials Science and Engineering at Northwestern’s McCormick School of Engineering, said in a news release.
First author Benjamin Shindel, a former doctoral student in Dravid’s laboratory and now a contractor with the U.S. Department of Energy’s National Energy Technology Laboratory, emphasized that tea’s effectiveness is due to its high active surface area, which facilitates the adsorption process, making it a practical solution given its status as the most consumed beverage globally.
“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,” Shindel said in the news release.
Methodology: Steeping Into the Details
The researchers explored various variables, including types of tea, tea bags and brewing methods. By creating water solutions with known quantities of metals like lead, chromium, copper, zinc and cadmium, and then adding tea leaves to these solutions, they measured the metal content before and after the steeping process.
Their findings highlighted that longer steeping times and certain types of tea leaves enhanced the adsorption process.
One of the critical discoveries was the effectiveness of cellulose tea bags, which outperformed cotton and nylon bags in adsorbing metal contaminants.
“The cotton and nylon bags remove practically no heavy metals from water. Nylon tea bags are already problematic because they release microplastics, but the majority of tea bags used today are made from natural materials, such as cellulose,” Shindel added.
The Impact of Steeping Time
The study revealed that the longer the tea leaves are steeped, the more metals are adsorbed. This means that allowing tea to brew for extended periods, much like how iced tea is prepared, could significantly increase heavy metal remediation.
“Any tea that steeps for longer or has higher surface area will effectively remediate more heavy metals,” Shindel added, noting that overnight steeping can remove substantial amounts of these contaminants.
Looking Ahead: Public Health Implications
While the research highlights the extraordinary passive benefits of tea in metal remediation, the team is cautious in suggesting tea as a primary solution for heavy metal contamination issues.
However, Dravid and his colleagues see potential applications in public health strategies, especially in regions where access to clean water is limited.
From initial experiments, the researchers estimate that a typical cup of tea can remove about 15% of lead from drinking water, a figure that could have meaningful public health implications.
“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,” added Shindel. He also suggested that this could contribute to lower incidences of heart disease and stroke in populations with higher tea consumption.
This study sheds new light on how a simple everyday habit like brewing tea could play a role in enhancing public health by mitigating heavy metal exposure — one cup at a time.