Let’s say you want to buy things with germs in them. There’s yogurt, of course, but there’s so much else.

You can buy pills for your gut, creams for your face, tablets for your breath. You can buy blueberry juice with germs, and pizza with germs. And a lot of these products make big promises about the benefits their germs will bring you. “Fungal Defense is specially formulated with ingredients that help maintain a balanced, healthy digestive environment,” for example. Natren Natasha’s Probiotic Face Cream “is enriched with DNA fragments of beneficial bacterial cells, which speed up the skins own natural renewal process.”

Did that last statement make not so much sense to you? Are