Researchers at Northwestern University have discovered another compelling reason to sip on tea: it has the ability to purify water by absorbing harmful metals. Their study, published on Monday in the journal ACS Food Science & Technology, suggests significant health benefits for tea drinkers, particularly against contaminants like lead and cadmium.
According to Benjamin Shindel, the study’s first author, “I’m not sure there’s anything uniquely remarkable about tea leaves as material... But what is special is the fact tea happens to be the most consumed beverage in the world.” This means the process of using tea leaves for metal absorption is practical for millions of people who consume tea daily.
The researchers measured levels of heavy metals such as lead, chromium, and cadmium before and after steeping different kinds of teas. They observed several key factors influencing the absorption of these contaminants. Chief among them is steeping time: the longer tea leaves are steeped, the more metals are filtered from the water.
Shindel noted, “Some people brew their tea for a matter of seconds and they are not going to get much remediation. Brewing tea for longer periods—like overnight for iced tea—could recover most of the metals, maybe even close to all of them.” This highlights the importance of not just choosing tea as an alternative but also paying attention to brewing practices.
Another noteworthy aspect of the research showed how the surface area of tea leaves contributes to their absorption capacity. When tea leaves are crushed or ground, their pores open up, dramatically increasing their potential to bind with contaminants. Shindel remarks, “When tea leaves are processed, they wrinkle and their pores open... Grinding up the leaves also increases surface area, providing even more binding capacity.”
The type of tea bag also affects the absorption of heavy metals. Research indicated cellulose-based tea bags were significantly more effective than those made from cotton or nylon, which barely absorbed any contaminants. Shindel pointed out, “Nylon tea bags are already problematic because they release microplastics, but the majority of tea bags are made from natural materials, such as cellulose... These may release micro-particles of cellulose, but it’s just fiber, which our body can handle.”
The findings reveal intriguing insights for public health. A typical cup of tea is capable of filtering out approximately 15% of lead, even if the water has toxic levels of contamination. “Across a population, if people drink an extra cup of tea per day, maybe over time we’d see declines in illnesses closely correlated with exposure to heavy metals,” said Shindel.
He speculated, “That could help explain why populations with higher tea consumption report lower rates of heart disease and stroke compared to those who drink less tea.” This not only emphasizes the drink’s health benefits but also indirectly advocates for greater awareness of water quality issues worldwide.
Although researchers do not advocate for replacing traditional water filters with tea leaves, their work sheds light on the significance of tea as part of the larger conversation about water safety and health consumption patterns. While tea is not the definitive solution to water contamination crises, it uniquely positions itself as both beneficial for individual health and potentially influential for broader public health outcomes.
The study invites both health professionals and consumers alike to reconsider their relationship with tea, not just as a comforting beverage but as something potentially protective against contaminants we might unwittingly ingest through our drinking water.
So, tea drinkers, keep doing what you’re doing—your daily cup of tea may be doing more than simply quenching your thirst.