Japanese people have special seaweed-digesting bacteria in their guts

A new study published in Nature has found that Japanese people have a special bacteria in their guts that allows us to digest seaweed:
The new study, published in Nature, reveals that these gut bacteria engaged in a gene swap, grabbing algae-digesting genes from marine bacteria that live on red algae like nori, the seaweed used to wrap sushi. The marine bacteria traveled on the seaweed into human digestive systems, where the crucial genes were transferred to bacteria in the gut.
I wonder if this really translates to Japanese people being able to eat more sushi than Americans can, as this article suggests. I certainly remember chomping on packets of seaweed for snacks when I was a kid — do you know any non-Japanese people who did the same and were not able to stomach it?

via Discover (Thanks, Bryan G!)


  1. so…. for us uncool westerners to gain this particular superpower we’d have to consume some ..?.. from a kindly Japanese ‘donor’?

    1. But Europeans have the ability, from genetic mutation, to digest dairy products after weaning off our mother’s milk.

  2. I doubt it means they can eat more but they certainly could get more out of it, as bacteria would break down the seaweed into more easily processed forms.

  3. My mom chomps up a seaweed storm no problem and she’s not Japanese. She is from another island chain in the Pacific, the Philippines. Wonder what that’s about.

  4. To clarify, I wasn’t suggesting that Japanese people can eat more sushi or that non-Japanese people can’t stomach it. But because Japanese gut bacteria have the special ability to break down some seaweed carbohydrates, they ought to be able to extract more energy from a sushi meal.

    1. extract more energy from a sushi meal

      Sounds like a pretty awesome superhero origin story…

  5. I’m a Canadian, of Irish descent, and I eat packages of dried nori all the time. I’ve never had digestive problems because of it.

  6. Americans are able to consume vast quantities of high-fructose corn syrup without harming their health.

  7. My sister and I consumed nori sheets like nobody’s business. For much of our childhood…without digestive “incident”. And we are very much so, not Japanese.

  8. NPR did a segment on this and the researcher being interviewed said that the bacteria in question actually doesn’t digest to the kind of seaweed that’s eatean, because it’s roasted (Although some folks are still eating raw seaweed on occasion). He described it as specifically having evolved to digest unroasted seaweed, which was eaten back in neolithic times. It still has the genes for that, but they’re not particularly relevant to the contemporary Japanese diet, apparently.

    I’m non-Japanese and I grew up eating packets of nori at all my friend’s houses. Never had any problem digesting it. I have one friend however who is powerfully sensitive to the odor of nori and has trouble eating her own food when it’s anywhere near her, like when we go out for Japanese-style spaghetti.

  9. I only repeat this because it’s on topic, I make no claims to the validity of the statement nor that it is “true” beyond the truth that this is a story I’ve heard on more than one occasion;

    I’ve heard repeatedly that the Japanese and other people who eat high amounts of rice, break down carbohydrates differently than people who do not. Alcohol is a carbohydrate. This is a factor for the perception that many Asians are quick to become drunk and why I, a pale white dude, pack on massive poundage when I eat a few cups of my beloved rice.

    Truth be told, I’d rather be able to consume mass quantities of rice than beer.

    1. Ahhh, but is not rice one of the main ingredients of American Light Low-Cal zero-taste clear-beer? Unlike the “healthier” naturally fortified robust beers of Europe.

    2. Don’t mean to get all nitpicky, but alcohol (ethanol) is not a carbohydrate. Neither chemically, nor biologically. It’s often accompanied by carbohydrates (e.g., beer, wine) and is usually made from fermentation of carbohydrates, but it’s not a carbohydrate itself.

      The perceptions related to Asians and alcohol intolerance stems from the fact that a large percentage of Asians produce relatively low levels of a liver enzyme involved in alcohol metabolism (aldehyde dehydrogenase).

  10. There is a long tradition of dried seaweed-eating on the east coast of canada (called dulce). I grew up nomming off the packages my dad would get once in a while. I wonder if they would find the same bacteria here, although it’s not so widespread anymore.

  11. I think you read the article backwards. I think what it said was that eating a great deal of seaweed transfers those enzymes to the gut, and since Japanese people eat more seaweed, they have the enzymes in high concentrations. They said the enzymes may help extract additional nutrients from foods but needed to do more study to be sure.

  12. edyong209: xtract more energy from a sushi meal

    grimc: Sounds like a pretty awesome superhero origin story…

    If I were a superhero, and the superpower I got was extracting more energy from sushi meals I WOULD BE PISSED!

    1. Able to extract the energy of a nuclear power plant from a sushi meal, Papu-Ai defends freedom and dispenses justice in his neverending fight against supermarket sashimi…

    2. Yeah, unless your power was to harness the complete nuclear fission of every atom in the sushi, and use it to fly and shoot energy beams out of your fingers and use radiation to look RIGHT THROUGH ladies’ clothes! I’m just sayin…

  13. Well on the same idea, the book On Food and Cooking points to the fact that a large portion of the population is lactose intolerant. But that percentage decreases heavily in areas of Northern Europe (like Norway/Finland/Sweden). Apparently much of their diets were milk/cheese based and their guts adapted the same way.

    Either way I eat a ton of dairy and love it.

  14. I’m calling bullshit. The experimental group was THIRTEEN people and the control was EIGHTEEN.

    1. Agreed… the numbers of the study made me wonder. I also have to wonder if you’d find this on other people exposed to raw seaweed.

      And now I’m craving nori sheets, spicy style.. Guess it’s off to T&T tomorrow. :9

  15. I agree with sloverlord (#8), I think that the intestinal flora in Japanese individuals acquired the ability to digest seaweed because seaweed is prevalent in the diet. But remember that genes in the intestinal flora are not part of the individual. Intestinal flora are colonies of different bacteria in the gut that help you digest your food, and the composition of bacteria varies depending on the diet. As far as I understand this, you do not “inherit” these bacteria from your parents – so a Japanese person born in the US eating a US diet would not have the same intestinal flora than someone in Japan. Likewise, a western person living in Japan might acquire some of these bacteria as part of their intestinal flora.

  16. I was introduced to Japanese cuisine, including seaweed in quantity, in 1964 and never had a problem with it. I don’t believe I have any Asian genes at all. I continue to enjoy sushi and other Japanese foods to this day.


  17. The folks in Nova Scotia (when I was a kid, 45 years ago) ate a type of seaweed called dulse, that apparently you can buy on-line, and it looks pretty damned healthy to boot. The stuff is slightly red, slightly salty, and not that bad, taste wise. It was pretty common among the relations that came out of central Novie, and there are alot of them

    1. I ate dulse with my Nova Scotia relatives 45 years ago. And I grew up in Ashland, rather near Cochituate. We seem to have the same life. I hope that you got better parents.

  18. I’m Japanese and I eat lots of nori and wakame and all that good stuff, but I feed the same thing to my non-Japanese roommates from time to time and they haven’t had any issues digesting it (or they just haven’t told me because they don’t want to hurt my feelings…)

  19. I often eat sushi/sashimi when I’m under the weather because I find it very easy to digest. I don’t know whether I’m absorbing the nutrients as well as a Japanese, but I sure feel fantastic after a gigantic plate of assorted nigiri… droooool

    I’ve also been snacking on nori for years, partly because I needed more iodine in my diet. Plus it’s delicious.

  20. I’m white as snow and I grew up munching on nori in packets as snacks too. my mother lived in Japan for a time before I was born, and raised us on lots of japanese food. As an adult, I still down tons of sushi. I’ve never had a problem.

  21. Huh. I eat dried nori as a snack (very nom-y, I might add) but I’ve never had any problems with it. As culturally diverse as my background is, I’m fairly certain I don’t have any Japanese genes. o.O

    Maybe some people just have a seaweed allergy?

  22. My wife is Japanese and eats nori like potato chips and while I (a brit) like them, within an hour of eating a tenth as much of them as she does, I get cramps and I’m eyeing the shortest route to the bathroom. It’s only with nori though, all other seaweed I’m fine with.

    Still, she’s allergic to eggs so swings and roundabouts.

  23. My kids mow through sheets nori no problem, and they are about as blonde hair – blue eyes as it gets. So to answer your question, no.

  24. This struck me right away as coming from the tradition of nihonjinron, or “writings on the Japanese people” (google it), that attempt to show how unique the Japanese are. I remember a BBC show where a scientist tried to say that Japanese hear Western music with one side of their brain, and Japanese music with the other. The findings here may or may not be true, but I always suspect the motives behind this sort of thing.

  25. Although we’re mixed race, including eastern Asian, no one in our immediate family is Japanese….and yet we all love to eat seaweed regularly, with no digestive issues as a result.

    Only one member of the family can eat dairy without taking Lactaid, however. Ironically, it’s the person who most looks Asian.

  26. I eat nori all the time. Munch on nori, wakame soup, nigiri sushi. Im no Japanese but I live in Japan. When I was in Canada I ate seaweed all the time too. So did my cat. My cat loved seaweed.

    So yes non nihon-jin eat seaweed too.

  27. I’m a pretty haole haole (a smidge of Comanche in there, but mostly a mutt of British and German descent) but I munch seaweed like it is going out of style. I still eat the packets of dried nori that I started eating as a kid in Honolulu. I also eat a lot of dulse flakes, arame, wakame, and hijiki. I love the prepackaged seaweed salad that I buy at the grocery too (same stuff they usually have at sushi restaurants, not sure what type of seaweed that is). I have never had any problems at all digesting any kind of seaweed.

  28. Folks, as said above, this story is not about people’s ability to digest seaweed. It’s not about tolerance or allergies or anything like that. These genes don’t affect your ability to eat seaweed or to “stomach it”.

    It’s about how much energy you can extract from the same food. Look, think about it like this: everyone has the ability to use a computer. Some people have the knowledge to use a computer WELL (programming, gaming, hacking etc.) but this doesn’t mean that people without that knowledge can’t switch it on and send an email.

  29. Japanese people are the most unique people on the planet!

    Did you know their tongues are formed differently, which is why the can’t say R? It’s totally true!

    They also have significantly shorter long intestines than non-Japanese people! This is also totally true!

    And lets not even get into the ways that their culture is the mostest differentestest and uniquestest in all of history since forever!

  30. Lisa, just think of all the money you could make regurgitating partially-digested dried seaweed snacks for gaijin. Target new mothers and cancer victims to maximize profitability.


  31. i wonder what kind of flavor this type of digestive tract would impart on the coffee bean

  32. Not sure if it’s related to the article or not, but when I eat seaweed salad…I definitely do not digest it all.

  33. I have a pretty serious seaweed allergy, although I think technically it’s more of an intolerance [I don’t blow up, but it is seriously unpleasant].

    Most people look at me like I’m insane or just lying, because it must be pretty uncommon. But it is severe enough that I even have to be careful about cheap ice creams that use certain seaweed gums, so I need to very clear when I eat at Japanese restaurants.

    That said, soy paper has made sushi fun to try again.

  34. @edyong209: What do you think about @Marshall above said about these bacteria only being relevant to eating raw, non-roasted seaweed? Might make sense in light of the fact that cooking often does make food a lot easier to digest.

    1. He’s right. I wrote something about this at the bottom of my article, linked to from the top:

      Personally, I’ve been eating sushi for around two years ago and I was intrigued to know if my own intestinal buddies have gained incredible new powers since then. Sadly, Czjzek dispelled my illusions. “Today, sushi is prepared with roasted nori and the chance of making contact with marine bacteria is low,” she said.

  35. Another Nova Scotian here… we still eat dulse (seaweed) like potato chips in my family!

  36. I am Italian, my wife is Irish, my friends are English/German/Puerto Rican and we all eat the seaweed-I guess this theory really doesn’t float.

  37. If I’m reading the Nature article correctly, it states that genetic material was transferred from the seaweed into the gut bacteria. If that’s right, then couldn’t the same thing happen with the modified DNA in GMO foods? I know this is already a point of discussion among anti-GMO people, but this story is even more scientific evidence that this transfer happens.

  38. Pfft. I have no trouble chowing down on packets of nori – and I’m not the least bit Japanese, let alone Asian.

  39. @misterjuju Bacteria have special mechanisms for exchanging DNA that Euchariotic cells (and human cells) are not known to have. Because of this the bacteria in your stomach can in theory pick up mutations from the bacteria on the food you eat, but your cells cannot pick up mutations from your food. There are other ways human cells mutate in response to their environment, but these are unlikely to be triggered solely by GMO foods.

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