Konnyaku: Miracle Diet Food or Gelatinous Murderer!?

Home / Konnyaku: Miracle Diet Food or Gelatinous Murderer!?

Around the world, konnyaku is known by many names: devil’s tongue, konjac, 蒟蒻, konjar, voodoo lily, snake palm, but to 45 people (since 1995), it is better known as the cause of death! Perhaps we should get to know this potential menace lurking in the (brightly lit) shadows of our local supermarkets and convenience stores a little bit better.

So, what is konnyaku, you ask? Originally used as a medicine in the 6th century, this seemingly magic substance is native to East Asia and grown primarily in China and Japan. In 2009, Japan produced 66,900 tons of konnyaku, with 89.5% of it coming from our precious Gunma Prefecture.

Konnyaku is produced from a perennial corm (potato), prized for it’s super starchy qualities. The plant itself takes about 3-4 years to grow and the corms remain good for another 4-5 years. The final product is usually made by mixing flour with limestone water to generate it’s rubbery viscosity. Despite having little to no taste, konnyaku is prized for it’s texture, and many products are produced using konnyaku including jelly, flour, bread, jerky, miso konnyaku, sashimi konnyaku, shirataki noodles, konnyaku balls, and it is often used as a vegan substitute for gelatin. (Do not forget that Jell-O contains ground up animal bones). Its sponge-like absorbency makes it the perfect additive to soak up the flavor of other foods and can be eaten raw, boiled, fried, or grilled.

Being high in fiber and extremely low in calories (about 10 calories in a big block), konnyaku is prized as a diet food all over the world (that is, where it has not already been banned). According to the Japan Konnyaku Association, konnyaku normalizes cholesterol, prevents high blood pressure, and because it consists of 50% water and 40% glucomannan (dietary fiber), the body finds it hard to digest, thus sliding right through you and cleaning out your intestines all the while giving you the illusion that you are full. Konnyaku has even been given the nickname of “broom for the stomach” (胃のほうき). This is good and all, but do not forget to eat other foods with actual nutritional value or you will learn the hard-way like Japanese writer, Soichi Ohyake, who in the 1960s, died from malnourishment by trying to diet on strictly konnyaku.

Konnyaku also often appears as Shirataki noodles in Oden, which, if you are not familiar, is a wintertime collection of multiple foods (like eggs, radish, chikuwa (fish paste cakes) kept in boiling hot water until consumed, usually for sale at your local combini. Oden is a seriously tasty treat if you are freezing in the cold heart of the relentless Japanese winter. Most Japanese people I have asked about konnyaku seem to like it, but there are some people who do not like the texture or the lack of flavor. One of my friends in Tokyo does not like it because of how it is utilized by teenage boys, but that is a story for another day.

Usually there are no additives to konnyaku and the final product looks something like a block of white frozen milk, but with seriously elastic jellified properties. Often, hijiki seaweed is added to the product during production, giving it a gray with black specks look when completed. However, be careful when preparing this food not to eat it before it is finished, otherwise you may end up with a serious tummy ache, a numb tongue, and possibly (but not surprisingly) death!

Many prefectures and towns in Japan grow konnyaku, but no prefectures grow as much as Gunma, and no town grows as much as my beautiful mountain town of Shimonita, which is known all around Gunma and the rest of the country for its prized welsh onions (negi) and konnyaku. In 2009, Shimonita produced an astounding 155,810 20kg bags of konnyaku, not bad for a town of only 10,000 people! It is no wonder people flock from all over Japan to hike in our vast mountains and enjoy our konnyaku in a variety of ways at a multitude of konnyaku-specialized road-side stands, drive-ins, and restaurants. You cannot drive anywhere in Shimonita without seeing konnyaku bursting out of the fields with the very idiosyncratic stem piercing out of the earth.

If you want to get your hands on some of the best, I recommend Maruhei Konnyaku Shop as the heart of the world’s konnyaku – they have it all and you can sample everything before you buy in the very place it was made. Crazy delicious dessert konnyakus (plum, the seasonal sakura, pina colada, sesame, etc.) always make a healthy and delicious snack or gift. You can even learn to make konnyaku at the Konnyaku Tezukuritai Taiken Dojo (translated as “place to study the way if you want to have the experience of wanting to make handmade konnyaku”). It costs 1000 yen for adults and 500 yen for children (high school students and below). Reservations can be made Monday-Friday by calling 0274-82-3206 between 8:30-17:00.

Before “konjac jelly confectionery products” were banned in the European Union in 2002 following the deaths of 18 children worldwide, The United States Food and Drug Administration issued warnings about elderly people and children consistently choking when consuming. People with little to no teeth seemed to find themselves gravely surprised when the substance they were consuming did not melt in their mouths like other common forms of gelatin. This led to a number of recalls and a major degradation of konnyaku’s street cred in North America, which may be why you have never heard of it before.

In Europe, the same thing was going on and after the EU konnyaku ban took effect, the market took a serious nosedive whilst the market of Locust Bean Gum, a legal alternative, saw a major increase in sales. Has this prohibition led to an underground konnyaku jelly market in Europe? Gangs and illegal importers, who of course can set their own prices, are now the only means of acquiring these sweet illegal jellies within the EU. Are kids in the London underground stealing money from their parents and pawning their mopeds to get their fix of this tasteless monster? Will konnyaku-smuggling donkeys flock to Switzerland and Liechtenstein and other non-EU nations to replenish their stock of the devil’s tongue!? Only time will tell; good luck Europe, but back here in Asia, anything goes and oh, it is going!

When I first came to Japan, I was on the fence about konnyaku. I had never seen it before and did not necessarily dislike it; the texture was simply something that took some getting used to. During my first bike ride through town, some people from the Shimonita City Hall were standing under a tent handing out free konnyaku to all passersby. On that day, when I hesitantly took my first bite of miso konnyaku, not yet knowing that I would eventually eat much more konnyaku than I could have ever imagined and would develop a deep love and taste for this gray starchy blob of tastelessness.

Learn to love konnyaku my friends, enjoy its magically healthy qualities and try it out in a variety of different ways; I am almost certain that you will find the one that is right for you, but…


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  1. Japanese Beef Stew Recipe and a Staub giveaway · i am a food blog i am a food blog – go food sun

    […] its unique texture and subtle flavor. It also comes as a noodle and a lot of people rave about how awesome the noodles are. You should be able to find konnyaku as either a loaf or noodle at any higher end […]

  2. Japanese Beef Stew Recipe and a Staub giveaway · i am a food blog i am a food blog – GofoodSun

    […] its unique texture and subtle flavor. It also comes as a noodle and a lot of people rave about how awesome the noodles are. You should be able to find konnyaku as either a loaf or noodle at any higher end […]

  3. Aquaria

    As of 2018, normal konnyaku is not banned in America, only the sweetened treats are.

    I’m able to buy a variety of konnyaku in its block or Shirataki form at Japanese markets, without problems. Shirataki noodles are even sold at my American supermarket.

    Like the article says, you need to be sure to chew your konnyaku thoroughly to avoid any risk of a choking hazard.

  4. June Gregory

    I’ve eaten a product called Better Than Noodles which is konnyaku and both times I vomited exactly 6 hours later!!!

    • Aquaria

      And? So? Less than 2 hours after eating potatoes, cayenne and most nuts, my face, tongue and more can get swollen and inflamed. And about another hour later, I’m vomiting and sometimes i can go into anaphylactic shock.

      Does that mean there’s something wrong with those foods? Of course not. It only means I have allergies to them. You may be allergic to konnyaku. It happens.

      That doesn’t mean anything in the grand design of things.

  5. David

    Here is the FDA notice regarding the choking hazard posed by specific konjac jell products: http://www.accessdata.fda.gov/cms_ia/importalert_105.html

  6. David

    Konnyakku based candy has caused some deaths by choking, and is apparently hard to dislodge once it gets stuck in one’s throat. At the least, it should probably not be given to children.

  7. Tatiana Vermeir


    I have been trying to make Konyaku myself at home, using Konjac and lime water. However, I never get the right texture.

    Have you got any idea where to buy these blocks? I cannot find them in the Asian supermarkets in Belgium and it seems impossible to buy them online (or it seems impossible to ship them to Belgium)

  8. Melissa

    Apparently konyaku itself is not dangerous at all. It is how the humans apply it in their diet. The people need education. It is like eating only sugar free hello and expecting to get all your nutrients from it.

  9. brisbane language school

    It’s hard to come by experienced people on this
    topic, but you sound like you know what you’re talking about!


  10. Confused

    How is konnyaku used by teenage boys? I must know! 🙂

  11. Out in the countryside are freemium museums | On⇔offline from Tokyo

    […] as konjac or devil’s tongue, see photo above – production in this country. According to this article, 89.5% of domestic production came from Gunma in […]

  12. Dahlia

    Hi, just wanted to point out that konnyaku is in fact very legal in the EU, well at least France. It is for sale in a lot of Japanese epiceries and most Asian supermarkets have it.

  13. Shania

    I don’t think it should be banned in America just because some people can not cook it properly and/or try to eat it the wrong way.

    • Marlina

      I think you are right…i produce vegan jello and mixed it between seaweed powder and konyakku and the taste is delicious…it is soft and can be chew easily by small kids in fact… even adults adore eating my vegan jello…it is simply depending on how you create it and cooked it.

      It is healthy too

  14. Sakura

    How do teenaged boys use konnyaku? I don’t understand.

  15. ed

    hi chuck,
    doing a bit of research on konnyakku. could i contact you to pick your brains?

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