Green tea, red flags: Matcha's hidden impact on iron levels

The 'healthier' caffeine source is gradually taking over traditional morning coffee, but experts warn of health risks - especially for young women.

The funky green tea drink we know as matcha has risen in popularity in Aotearoa since the start of 2024.

Several cafés, restaurants and petrol stations now offer the drink, after it gained popularity on social media.

However, nutritionists say a compound found in the drink can significantly reduce the body's ability to absorb iron.

Registered nutritionist Olivia Green says it's hard for the body to absorb matcha with meals because the polyphenols restrict iron absorption.

“Iron is essential for carrying oxygen around the body and plays a key role in energy production, immune function and growth,” she says.

Plant-based foods such as lentils, nuts, beans, spinach, and fortified cereals contain non-haem iron.

Green says people typically consume tea, coffee or matcha with breakfast foods such as eggs in the morning.

“We get a lot of our daily iron from these foods, but if you are having matcha with meals, your body cannot absorb that iron,” she says.

University of Auckland student Liv M says this risk became all too real for her. Despite consuming what she thought were healthy, balanced, and iron-rich meals, doctors diagnosed her with iron deficiency last year.

“I would feel sluggish throughout the whole day, like I was about to crash at any moment,” Liv says.

“I didn't realise that the matcha I was having with my breakfast was actually preventing my body from absorbing all the iron I would be getting.”

Liv is advocating for more awareness of what we put into our bodies after recently completing her third iron treatment.

“I was eating healthy, but the matcha I was having was just blocking my body from any of the nutrients I would have been getting. Iron being the main one,” she says.

Anyone can struggle with iron absorption, especially people who menstruate, are pregnant, follow vegan/vegetarian diets, and teenagers during growth periods.

Green says that despite the impact matcha can have on iron absorption, it still offers several health benefits.

Matcha contains powerful antioxidants, including the amino acid L-theanine, which can support focus, relaxation, fiber and moderate amounts of caffeine. Studies suggest that it may also reduce stress and support heart and brain health.

Green says there is good news for matcha lovers.

"People do not need to stop drinking matcha but just be mindful when they consume it.

“For those who are particularly at risk of low iron such as young women, my recommendation is to leave 1-2 hours between matcha and meals. Giving your body the best chance to absorb iron needed for energy, immunity, and brain health,” she says.

Our journalists sometime use AI tools for stories, which are then checked by humans for accuracy. AI was used to help with research for this story.