The world has developed a thirst for matcha – a bright green Japanese drink that's sought after for its health benefits and caffeine.
However, the drink of choice for many may have a downside. Not only is its popularity drying up global supplies, but drinking too much of it could contribute to an iron deficiency.
Nutritionists warn the green lattes can affect iron absorption and vegetarians are at a higher risk than meat eaters.
Matcha is made from the green tea plant, Camellia Sinensis, which is ground into a powder. Because it’s grown in the shade the plant produces more chlorophyll, which not only gives it a deep green colour but also means it contains more nutrients.
Rob Hobson, a nutritionist and author of Unprocess Your Family Life, explains the drink does have health benefits. “It contains polyphenols which protects the body against oxidative damage. So, it helps to reduce inflammation which then helps to protect against chronic diseases,” he told the Independent.
“Because it contains caffeine it helps with mental focus. But it also contains L-theanine which helps to lessen that jittery edge that you get from caffeine,” he added.
Research has also suggested these polyphenols in matcha can reduce the risk of heart disease. But the same health boosting polyphenols also make it harder for the body to absorb iron.
Gunter Kuhnle, a professor of nutrition and food science at the University of Reading explained matcha tea can affect iron absorption by binding the (non-haem) iron that is found in many plant foods – such as lentils, leafy greens and tofu.
“It contains the compounds catechins and tannins – which are both polyphenols – that can bind to iron in the digestive tracts, and this stops them from being taken up by the body,” Professor Kuhnle told the Independent.
“These complexes then pass through the gut and are not useful for the body – this can reduce iron uptake by up to 50 per cent, but this varies a lot between individuals and depends on the timing of the meal and the type of food,” he added.
He explained there is a similar problem with green tea because it also contains high levels of polyphenols. Although rare, in one instance a 48-year-old man became anaemic from excessive green tea consumption Professor Kuhnle said.
Mr Hobson stressed that you don’t need to worry if you have a balanced diet, but warned vegetarians are at a greater risk.
That’s because it only affects non-haem iron which is in tofu and lentils and not haem iron which is found in meat.
“If you are vegan or vegetarian and you are relying on lentils, leafy green and tofu for your iron, then you might want to avoid drinking matcha with your meals because it can inhibit iron absorption in the gut,” Mr Hobson said.
He also stressed that if you are low in iron anyway and take iron supplements, you should avoid taking these at the same time as drinking a matcha.
An iron deficiency, also called anaemia, can cause tiredness, shortness of breath, paler skin, headaches and heart palpitations, according to the NHS.
Low iron is common among teenage girls, vegans and vegetarians with a study by Lund University in Sweden finding 38 per cent of participants who were teenage girls and 70 per cent of participants who were vegetarian or vegan, affected by the deficiency.
If you want to reap the health benefits of matcha, in addition to not drinking it at mealtimes, make sure to avoid adding a lot of syrup or cream. Mr Hobson instead suggests the healthiest option is to drink it plain.
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