YOUR favourite brew could lower your risk of heart attack and stroke – for a surprising reason.
Brewing tea is good for your health as it purifies the water by removing toxins, new research revealed.
The brewing process removes “significant” amounts of toxic heavy metals from drinking water, scientists said.
And the longer the steeping time, the more contaminants are adsorbed.
Recent research suggests a connection between heart disease and exposure to toxic heavy metals.
Over time, heavy metal exposure eventually results in an increased risk of high blood pressure, arrhythmia, and atherosclerosis – all of which make heart attacks and strokes more likely.
American researchers showed that brewing tea “naturally adsorbs” heavy metals, such as lead and cadmium, effectively filtering dangerous contaminants out of drinks.
They explained that heavy metal ions stick to – or are absorbed by – the surface of the tea leaves, where they stay trapped until the used tea bag is disposed.
Study senior author Professor Vinayak Dravid, of Northwestern University, Illinois, said: “We’re not suggesting that everyone starts using tea leaves as a water filter.
“For this study, our goal was to measure tea’s ability to adsorb heavy metals.
“By quantifying this effect, our work highlights the unrecognised potential for tea consumption to passively contribute to reduced heavy metal exposure in populations worldwide.”
He suggested drinking more tea may help lower the risk of heart attack and stroke.
[bc_video account_id=”5067014667001″ application_id=”” aspect_ratio=”16:9″ autoplay=”” caption=”The 8 subtle signs of lingering ‘holiday heart syndrome’ – and when you risk blood clots and stroke” embed=”in-page” experience_id=”” height=”100%” language_detection=”” max_height=”360px” max_width=”640px” min_width=”0px” mute=”” padding_top=”56%” picture_in_picture=”” player_id=”default” playlist_id=”” playsinline=”” sizing=”responsive” video_id=”6366653247112″ video_ids=”” width=”640px”]Prof Dravid added: “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.
“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.”
[authenticated-scripts src=”%3Cscript%20class%3D%22palin-poll%22%20src%3D%22https%3A%2F%2Fwww.thesun.co.uk%2Fpollingwidgets%2Fv3%2Fwidget.js%3Fquestion_id%3D108094%26game%3Dpolling%22%3E%3C%2Fscript%3E” type=”embedded” width=”100″ /]First author Benjamin Shindel, a former Northwestern University PhD student, said: “I’m not sure that there’s anything uniquely remarkable about tea leaves as a material.
“They 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.
“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.”
To conduct the study, published in the journal ACS Food Science & Technology, the Northwestern research team analysed how different types of tea, tea bags and brewing methods affect heavy metal adsorption.
[boxout headline=”Is tea good for your health? “]Recent research suggests that regularly drinking tea for many years may lower your risk of dying from heart or circulatory disease.
According to the study adults who drink up to two cups of tea a day for more than seven years have a 19 per cent lower risk of dying from a heart attack or stroke than those who drink less, or no tea at all.
Every extra cup of tea a day lowered their risk by 4 per cent, suggests the research published in March in the journal Current Developments in Nutrition.
However, the research does not say which types of tea people were drinking – whether it was black, green or herbal tea, or if people added milk or sugar to their brew.
To read the health benefits of tea, the British Heart Foundations suggests you try not to add sugar, or use a low-fat milk if you’re having several cups a day.
This is because eating too much sugar and saturated fat can lead to weight gain and increased cholesterol levels, which increases your risk of heart and circulatory conditions including heart attack and stroke.
Source: BHF
The varieties tested included “true” teas – such as black, green, oolong and white – as well as chamomile and rooibos teas.
The team also examined the differences between loose-leaf tea and tea bags.
They created water solutions containing lead and other metals, and then heated the solutions to just below boiling point.
They then added the tea leaves, which steeped for varying periods of time, from a few seconds to 24 hours.
After steeping, the researchers measured how much of the metal content remained in the water.
By comparing metal levels before and after adding the tea leaves, they were able to calculate how much was removed.
After testing different types of bags without tea inside, the researchers found cotton and nylon bags only adsorbed “trivial” amounts of the contaminants.
But the findings showed that cellulose bags worked “incredibly well”.
The key to a successful sorbent material – materials that can collect molecules from another substance – is high surface area, researchers explained.
Similar to how a magnet attaches to a refrigerator door, metal ions cling to the surface of a material – so the more area for the particles to stick to, the better.
Dr Shindel believes that cellulose, which is a biodegradable natural material made from wood pulp, has higher surface area than sleeker synthetic materials.
He said: “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.
“These may release micro-particles of cellulose, but that’s just fibre which our body can handle.”
When comparing different varieties of tea, the team found that tea type and grind played “minor” roles in adsorbing contaminants.
Finely ground tea leaves, particularly black tea leaves, adsorbed slightly more metal ions than whole leaves, which researchers attributed to surface area.
Steeping time played the most significant role in tea leaves’ ability to adsorb metal ions.
The longer the steeping time, the more contaminants were adsorbed.
Dr Shindel said: “Any tea that steeps for longer or has higher surface area will effectively remediate more heavy metals.
“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.”
Although results depend on several factors, the researchers concluded that tea brewing removes a “significant” amount of lead from drinking water.
As much as 15 per cent of lead could be removed, even with concentrations as high as 10 parts per million.
The estimate applies only to a “typical” cup of tea, which includes one mug of water and one bag of tea, brewed for three to five minutes.
Dr Shindel said: “Ten parts lead per million is obviously incredibly toxic.
“But with lower concentrations of lead, tea leaves should remove a similar fraction of the metal content in the water.
“The primary limiting factor is how long you brew your tea for.”