The hidden health dangers lurking in your cup of tea – as experts warn tea bags can release billions of toxic microplastics into the body

A cup of tea, or four, is a daily ritual for millions of Brits, with the nation estimated to consume around 165million cups a day, about two-and-half per person.

While much has been made about the general health benefits of a brew, a recent study has raised the frightening possibility that each tea bag could be releasing billions of potentially harmful plastic particles into your body.

But it’s far from the only health concern linked to a cup of tea. Here, MailOnline explains all of the potential hidden health dangers.     

Potentially cancer causing and fertility reducing microplastics 

A shocking study this week suggested that every tea bag you use to make a brew could be potentially releasing billions of dangerous microplastics into your body.

Microplastics are small plastic pieces of less than 5mm in length that have become increasingly abundant in the environment over time.

They are found in the water, the air and now tea. Once in the body microplastics can penetrate deep into tissue thanks to their microscopic size. 

In experiments, scientists from Universitat Autònoma de Barcelona tested a number of teabags made from nylon, polypropylene or polymer filters, mixing hot water with each and testing the results. 

They found microplastics released in tea were mostly absorbed by mucus-producing intestinal cells.

However, they found some were so small they could even enter the cell nucleus – the part of the cell that houses genetic material.

While all were found to release huge amounts of microplastics the polypropylene teabags were the worst offenders, releasing approximately 1.2 billion particles per millilitre, each with an average size of 136.7 nanometres. 

The implications of what microplastic exposure means for human health in general, both via tea and other routes, are still being explored.   

But there is a growing body of evidence to suggest that plastics could play a key role in early-onset cancer genesis, where healthy cells turn cancerous.

Some scientists have suggested microplastics’ presence in tissue could be increasing the risk of cancer, including a mysterious rise of bowel cancers in young people.

Others have even found microplastic in human sperm and theorised its presence could be playing a role in a global decline in fertility.

Oesophageal cancer 

Drinking piping hot tea may double your risk of developing a type of cancer, some studies suggest.

Research on people in Iran found those who regularly drank tea at a steamy 60°C (140°F) or higher saw their risk of oesophageal cancer rise by 90 per cent.

The oesophagus is the muscular tube that carries food and drink down the throat and into the stomach for digestion. 

The theory is that repeated exposure to hot liquid damages the cells, leading to changes that could become cancer.

However, while intriguing, experts have highlighted that most Brits don’t drink tea at this temperature due the habit of adding milk which rapidly cools it down.

Cancer experts have also said if the increased risk posed by hot temperatures is real it’s likely an accumulative effect of years of exposure to these scalding fluids.

This means those Brits who have occasionally gulped down a too-hot sip of tea are unlikely to have any significant increased risk of this type of cancer.

Kidney stones 

Oxalate is a natural chemical found in many types of plants including tea.

While harmless to most people, the one in 10 Brits prone to kidney stones must limit the number of oxalate-rich foods and drinks they consume.

Having too oxalate much over a long period could contribute to a stone developing.

While normally passed in urine without issue larger kidney stones can be extremely painful and lead to infections or even impair kidney function if left untreated. 

It’s for this reason that the NHS advises people suffering from kidney stones to limit their intake to only two to three cups of tea per day.

They also recommend cups be consumed with plenty of milk as the calcium within it binds to oxalate neutralising it and helping stop the stone developing.

Potential iron deficiency  

Tannins are a type of natural chemical found in tea leaves that have been credited with a number of the health benefits due to their antioxidant properties.

However, if you’re one of the 8 per cent of British women or 3 per cent of men with an iron deficiency you may want to limit the number of cups you have daily.

This because tannins can interfere with how the body absorbs iron, potentially worsening anaemia. 

If you’re taking iron supplements experts advise against consuming tea two hours before or after to ensure you absorb the iron needed to make the red blood cells that carry oxygen around the body.

Beware of hidden caffeine

When most people think of caffeinated drinks coffee and energy drinks are often the first that spring to mind.

But tea is also a little known source of the stimulant that can carry a host of potential issues some need to be aware of.

While not as caffeine rich as coffee an average 200ml cup of tea still contains 45mg of the stimulant.

However, the exact caffeine content of tea can vary greatly due to factors like brew time, water temperature and type of tea.

A Department of Nutritional Services report previously found a cup of black tea contains anywhere between 23 and 110mg of caffeine.

The NHS recommends people consume less than 600mg of caffeine per day to avoid issues like anxiety, sleeplessness, agitation, palpitations, diarrhoea and restlessness.

However, Brits with certain sensitive heart conditions and taking medications that could interact with the stimulant may need to limit watch their caffeine intake, and this can include tea.

Pregnant women are also advised to limit their caffeine intake to just 200mg per day due to increased risk of miscarriage or low birth weight.

The stimulant is thought to cause spikes in blood pressure that can influence blood flow to the placenta.

But some studies have suggested even women who consume less than the 200mg limit still have an increased risk of low-birth weight babies or premature newborns.

Other scientists have linked expectant mothers consuming caffeine to children suffering developmental delays.

However, this remains an area of scientific debate with some experts suggesting research linking consumption to problems is overblown.

But these experts have added that pregnant women should still follow guidelines from officials on daily caffeine intake limits. 

Teeth discolouring 

One of the most common complaints from drinking tea is staining of teeth.

This is due to high tannin content of the drink which can lead to the famous yellow stains.

While this can be unsightly and harm people’s self-confidence this is purely a cosmetic issue and can be mitigating by maintaining good oral hygiene.