It’s not as straightforward as matcha directly causing hair loss, says Jessica Shand, a naturopathic nutritionist. It could actually come down to how — and when — you’re drinking it, as well as your overall diet, iron levels, and the quantity of matcha you consume. “Matcha contains tannins,” Shand explains, “which are natural compounds that can inhibit the absorption of non-heme iron (the type found in plant-based foods) when consumed in large amounts (more than two to three cups) or too close to meals.” If you’re already low on iron (many of us are: iron deficiency is said to affect around one billion people globally), it can quietly become an issue, especially for women of reproductive age. Over time, Shand says, poorly timed or excessive consumption of matcha could lead to suboptimal iron levels. It’s this which can actually impact hair health.