P: Yes. Thank you. There’s a cool little riff in the new book about seaweed. The Japanese have a gene in one of the common gut bacteria that the rest of us don’t have that allows them to digest seaweed. It was just recently discovered. As often is the case, foods carry on them the microbes adapted to break them down—they are just waiting for them to die. It’s the same thing that makes the sauerkraut go—there’s a lactobacillus on every cabbage leaf waiting for it to bruise. Anyway, there was a marine bacteria, I forget the name of it, that was found with seaweed and the Japanese were exposed to enough of it, over enough years, that the gut bacteria acquired a gene from it, which is something bacteria do. They just pick up genes, as they need them, like tools. This one got into the Japanese microbiome and now allows them to digest seaweed, which most of us can’t do.
I thought well, we’d be getting it pretty soon, but in fact we won’t. They didn’t used to toast their seaweed. We toast ours; it’s been cooked and sterilized, so we’re killing the bacteria.
R: At a good sushi bar in Japan, they would run it over a flame. They will do it until they crisp it, so when you get it, it has that really crisp sheet of seaweed, the warmth laid around the soft rice.
P: They must have, for many years, eaten it raw. They may have been eating seaweed in other dishes, too. It’s in soup.
R: So we can’t metabolize it?
P: Nope. We get nothing from it except the taste on the tongue. It’s a shame, isn’t it, because I love seaweed. Anyway, the science kind of absorbed me in this project.
R: Where did you learn it?
P: I talked to a lot of microbiologists at [UC] Davis who work on sauerkraut and other fermented foods, trying to figure out how it happens and what it does for our bodies. It’s a succession like any other ecosystem. One species starts the fermentation and it’s fairly acid-tolerant, and it acidifies the environment to a certain extent. Then another microbe, more acid tolerant, comes along and so on until you get to L. plantarum, which is the acid-loving oak of the sauerkraut ecosystem, the climax species. And then it’s done.
One woman in the large group at the next table stops by on her way out to say how much Michael means to her. Her book group meets monthly at Bell & Anchor; she proudly proclaims that The Omnivore’s Dilemma is required reading at her son’s high school. Michael looks slightly pained.
P: I feel like [my book] has been inflicted on a lot of kids.
R: What are you going to do next?