If you have searched for matcha and heavy metals recently, you are not being paranoid. Two of the most trusted consumer testing organisations in the German-speaking world — Stiftung Warentest and Öko-Test — have both published tests on matcha, looking at aluminium, lead and pesticides. Austria's VKI ran a similar test. The results got a lot of attention, and not much of it came with a calm explanation. Here is one.
Why matcha is a different case from ordinary green tea
With normal green tea you pour hot water over the leaves and then throw the leaves away. Most of what the leaf absorbed from the soil stays in the leaf and goes in the bin. Matcha is the opposite: the leaf is stone-ground into powder and you drink the whole thing. Whatever is in the leaf ends up in your cup. That is the entire reason matcha shows higher heavy-metal readings than steeped tea — not because matcha is grown differently or badly.
What the tests found
Across the tested products, aluminium levels ranged roughly from 0.4 to 2.3 milligrams per gram of powder. That is a spread of nearly six times between the cleanest and the most loaded product on the same shelf. A handful of samples were flagged as noticeably high; most were not. Organic-certified powders came out lower on average in the Austrian test. Lead was measurable in matcha but was generally the smaller concern of the two.
For context, the European Food Safety Authority works with a tolerable weekly intake for aluminium of 1 milligram per kilogram of body weight — for a 70 kg adult, 70 mg a week. Aluminium is also in drinking water, baked goods, vegetables and cosmetics, so tea is one line in a much longer list. The sensible reading of these tests is not "stop drinking matcha". It is "a bowl or two a day is a normal amount, and it matters which matcha you buy".
What to check before you buy
- Named origin. A real region — Kagoshima, Uji, Yame — not just "Japan" or, worse, no country at all.
- First harvest. Later pickings use older, coarser leaves, which sit longer on the plant and accumulate more.
- Single cultivar rather than a blend. A blend can quietly change from lot to lot; a single cultivar is traceable.
- A seller who will answer the question. Ask for the analysis paperwork for the batch you are buying. A serious supplier has it. Silence is the answer.
Where our matcha stands
Every Bonsai matcha is grown, milled and sourced in Japan — Kagoshima and Kyoto — from named single cultivars, first harvest only, stone-ground in small batches. Nothing is blended in, and nothing is milled outside Japan. We also run a café in Barcelona where the same tins are served every day, which is a harder thing to hide behind than a website.
If you want to see the documentation for a specific tin before you order, write to us and we will get it from our supplier for that lot. That offer is open to anyone, customer or not.