Latest news with #Shindel
Euronews
26-02-2025
- Health
- Euronews
Scientists have discovered a new health benefit from the world's most consumed drink
The potential health benefits of tea have been widely reported but scientists have discovered another one to add to the list. Tea leaves would act as a filter removing potentially harmful heavy metals like lead from water, according to a new study. Researchers from the United States tested different varieties of tea - green, black, oolong, white, chamomile, and rooibos - under typical brewing conditions with water containing known amounts of lead and other metals (chromium, copper, zinc, and cadmium). Exposure to lead can lead to chronic health problems, with high doses causing brain and kidney damage in the most severe cases. After brewing at 85 degrees Celsius, they evaluated how much of the metals were absorbed at different time intervals. Preparing a typical cup of tea could lead to a 15 per cent removal of lead from drinking water, according to the findings published in the journal ACS Food Science & Technology. '[Tea leaves] have a high active surface area, which is a useful property for an adsorbent material and what makes tea leaves good at releasing flavour chemicals rapidly into your water,' Benjamin Shindel, who was a PhD student at Northwestern University in the US and the study's first author, said in a statement. He also highlighted the practicality of the process with tea being the most consumed beverage in the world with 6.5 million tonnes being consumed in 2022. '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,' he added. The transformation of tea leaves enhances their ability to bind with certain substances with black tea being slightly more effective than other varieties. Grinding the leaves also seems to amplify the effect, by enlarging the overall surface area that can capture metal. Infusion time and bags are also factors A longer brewing time was associated with a higher lead reduction, according to the results. 'Any tea that steeps for longer or has higher surface area will effectively remediate more heavy metals,' Shindel said. '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,' he added. Researchers also observed that the presence of a tea bag was a contributing factor in the process. Cellulose bags, made from wood pulp, were the most effective in trapping metal ions. 'The cotton and nylon bags remove practically no heavy metals from water,' Shindel said. '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. These may release micro-particles of cellulose, but that's just fiber which our body can handle'. These filtration properties can be added to the list of benefits associated with tea consumption, such as enhanced cardiovascular health and a protective effect against neurodegenerative diseases. '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,' he said.
The Guardian
25-02-2025
- Health
- The Guardian
Brewing tea removes heavy metals from water, study finds
The medicinal effect of a cup of tea is no surprise to anybody who has headed straight to the kettle after a laborious work meeting. But researchers say they may have found a more scientific explanation for why it is associated with health benefits. Scientists at Northwestern University in the US have found the brew removes charged atoms, or ions, of heavy metals from water. Benjamin Shindel, the first author of the research, said that while scientists may consider whether the flavour chemicals in tea are driving associated health benefits, the new study suggests an alternative. 'I think the one possible better explanation might be that it's because it's removing metals from water,' he said, adding the team found a cup of black tea brewed for five minutes reduced the concentration of lead ions in water by about 15%. While the team did not test the possible ramifications for health, Shindel said that even in a country such as the UK, where lead levels in drinking water are unlikely to be high, there could be a small effect. 'It's possible that on the margins, tea consumption is reducing [people's] metal intake by a very small amount, and perhaps over the population of the UK, that's reducing diseases associated with metal consumption by another commensurately very small amount,' he said. Among other studies, previous research has suggested people who drink tea may have a lower risk of stroke, dementia and even death. Writing in the journal ACS Food Science & Technology, Shindel and colleagues reported how they brewed tea with different batches of water containing known concentrations of heavy metal ions. They then checked the concentration of these ions after different periods of steeping, using solutions without tea as controls. Working with black tea, they found the brew reduced the concentration of all the metal ions tested, including lead, chromium and cadmium. They then focused on lead, finding longer brewing times of black tea and higher temperatures of water were associated with a greater reduction in the concentration of lead ions. What is more, ground tea had a greater effect than whole leaves. The team also found that, at least for the batches they tested, black, green and white teas reduced the concentration of lead ions in the water to a greater degree than camomile, rooibos and oolong teas when left to steep for 24 hours to reach equilibrium. In the case of bagged tea, the materials also mattered, with empty cellulose bags found to reduce the concentration of lead ions, whereas empty cotton and nylon bags did not. Prof Michelle Francl of Bryn Mawr College in the US and the author of Steeped: The Chemistry of Tea, who was not involved in the work, said: 'If you are concerned about heavy metals in your water, don't think that drinking tea is the solution.' However, she added that the study 'suggests some interesting directions' for developing sustainable and accessible ways to 'removing contaminants from water, a critical need in many parts of the world'.
