A trendy ‘health’ drink popular with teenagers and young adults can trigger fatigue, shortness of breath and even heart problems, experts have warned.

Matcha – a Japanese concentrated form of green tea known for its vibrant colour – has become a familiar sight in supermarkets and coffee shops in recent years.

Starbucks sells an iced matcha latte, while Tesco stocks a wide range of matcha teas and ready-made drinks.

Health influencers claim drinking it can increase focus, reduce anxiety and lower blood pressure. But mounting evidence suggests too much can trigger iron deficiency. Left untreated, this can raise the risk of severe infections as well as life-threatening heart failure.

Iron, found in red meat and a variety of vegetables, is crucial for the production of red blood cells, which transport oxygen to the organs. It is also vital for a healthy immune system.

Experts now say that drinking just one matcha tea a day could cause problems.

Research suggests teenage girls, pregnant and post-menopausal women are at the highest risk of a matcha-related iron deficiency.

‘People need to be aware of the potential risks of this drink,’ says Dr Jeannine Baumgartner, an expert in nutrition and researcher at King’s College London, who has studied matcha. ‘There is a real danger of a deficiency, particularly for younger women who have higher iron needs.’

Matcha is a vivid green, caffeinated powder made from the ground leaves of the Camellia sinensis tea plant – a type of green tea. A 2022 review found that 14 studies suggested that regular consumption improves brain function, reduces stress and can aide weight loss.

In the past year alone, sales of matcha products have doubled in the UK. The arrival of the US cafe Blank Street to Britain’s high streets in 2020 is thought to have led to a surge in the popularity here, with its range of matcha teas combined with other flavours such as blueberry and white chocolate.

But it has long been known that green tea can, in some cases, trigger an iron deficiency.

This is because it contains high levels of tannins – a compound which gives tea its bitter flavour.

Research shows that tannins attach to iron molecules in the digestive system and prevent them from being absorbed.

A major review of over 150 studies in 2010 published by the Journal of Chinese Medicine found that consumption of

more than three cups of regular green tea a day reduced iron absorption. However, it is believed that matcha has an even greater effect, as one cup has nearly seven times as many tannins as a similarly sized green tea.

As well as the tannins, caffeine has also been shown to reduce iron absorption and, per gram, matcha can contain up to four times as much caffeine as coffee.

Experts say this means that even one matcha a day could have health impacts.

‘Matcha is much more problematic than green tea, as it is more concentrated so affects iron absorption even more,’ says

Prof Baumgartner. ‘Even one cup, if it is poorly timed, either during or up to two hours after a meal, will affect your iron levels.’

Iron deficiency is already a problem. Three per cent of men and 8 per cent of women in the UK have the iron deficiency condition anaemia, and it is on the rise. Symptoms include a yellowing of the skin, dizziness and depression.

Last year there was a tenfold rise in the number of people hospitalised with iron deficiency, with nearly 200,000 being admitted.

But there are steps that matcha drinkers can take to protect themselves against this complication.

‘If you add milk or lemon juice, it can neutralise the tannins, which can help with iron absorption,’ says Sarah Carolides, a London based nutritionist. ‘It’s also best to avoid using oat milk in your matcha latte as oats contain phytates, an acid which can also interfere with iron absorption.’

Timing is key for those considering a cup of green tea.

Prof Baumgartner recommends against drinking matcha within three hours before or after a meal. A 1983 study revealed a cup of green tea while eating a hamburger meal reduced iron consumption by 68 per cent.

As drinking habits change experts are calling for the guidelines to doctors looking out for iron deficiency to be updated.

‘Doctors and GPs are not aware of the link between drinks and iron absorption and that really needs to change,’ says Prof Baumgartner.

 What’s the difference?

The early symptoms of both are similar – warm to the touch, red and often painful.

But ulcers are open sores that develop when an organ’s lining or the skin breaks down but doesn’t heal properly.

They can occur on the stomach, intestines, skin or in the mouth. Ulcers can become irritated, painful and sometimes require antibiotics.

Abscesses, painful pockets of pus caused by the body trying to fight infections, are usually closed internal lumps.

They can form under the skin, in teeth or inside the body and are usually treated with minor procedures to drain the pus.

Patients are often given antibiotics and pain relievers.