Nattokinase: History and Origins

Nattokinase has an unusual history for a natural-medicine ingredient: it is one of the few substances on this site with a genuine discovery, a named discoverer, and a date. The enzyme itself is brand new to science — it was first described and named in a 1987 research paper by the Japanese researcher Dr. Hiroyuki Sumi — but the food it comes from is ancient. Natto, the sticky, stringy fermented soybean dish of Japan, has been eaten for roughly a thousand years, and its roots reach back further still into the soybean-fermenting traditions of East Asia. This article keeps those two timelines clear: the long, cultural story of natto the food, and the short, modern, well-documented story of nattokinase the enzyme that was eventually found hiding inside it. Where the record is firm, we say so; where a claim is legend, folklore, or still uncertain, we name it as such.

Table of Contents

  1. Two Stories in One Food
  2. The Ancient Origins of Natto
  3. The Straw and the Horse: Natto's Origin Legends
  4. What "Natto" Means
  5. From Rice Straw to Pure Starter Culture
  6. Dr. Hiroyuki Sumi and the 1980s Discovery
  7. Naming the Enzyme: Nattokinase
  8. From Breakfast Bowl to Capsule
  9. Research Papers and References
  10. Connections
  11. Featured Videos

Two Stories in One Food

It is worth being clear from the start about what nattokinase is and is not, because its history is easy to muddle. Natto is the food: whole soybeans that have been cooked and then fermented by a specific bacterium, producing a pungent, sticky dish that has been part of the Japanese table for centuries. Nattokinase is one single enzyme produced by that bacterium during fermentation — a protein that, in the laboratory, dissolves the fibrin that holds blood clots together. The enzyme is present in the food, but the purified, dose-measured supplement sold today is a modern product, separated and concentrated long after the food itself became a tradition.

So this page tells two stories that meet only at the end. The first is genuinely old and genuinely cultural: nobody invented natto, and it has no single creator — like most fermented foods, it emerged from the accumulated practice of many people over many generations. The second is genuinely modern and genuinely scientific: nattokinase the enzyme was discovered, by a particular researcher, working on a particular problem, who gave it its name. Keeping the food and the enzyme apart is the key to telling either story honestly.

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The Ancient Origins of Natto

The deep background of natto is the long history of fermented soybeans across East Asia. Soybeans were domesticated on the Asian mainland, and the practice of fermenting them is older than natto itself: China developed fermented-soybean foods such as douchi well before natto appears in the Japanese record, and soybeans and rice were carried from the mainland to Japan in antiquity, during the Yayoi period. Some food historians suggest that a natto-like food could have arisen more or less by accident wherever cooked soybeans were stored warm and damp — which is why a few accounts describe natto as something that may have been "co-developed" in more than one place rather than springing from a single point of origin.

What the documented record supports is that natto as a recognisably Japanese food took shape in the northern and eastern parts of Japan around a thousand years ago, give or take a few centuries — the Encyclopædia Britannica places its origin at roughly 1,300 years, while many other accounts say "about 1,000 years." The exact figure is uncertain, so this page treats natto as genuinely old without fixing a precise birth date. By long tradition the city most associated with natto is Mito, in Ibaraki Prefecture, which to this day calls itself the home of natto and remains the centre of its culture in Japan. Natto became a widespread, everyday food during the Edo period (1603–1867), when street vendors are recorded selling it in the cities and its popularity spread outward from the regions where it began.

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The Straw and the Horse: Natto's Origin Legends

Like many old foods, natto has gathered colourful origin stories — and these should be read as legends, not history. The most famous attaches natto to the eleventh-century warrior Minamoto no Yoshiie (1039–1106). The tale holds that during a military campaign in north-eastern Japan, around 1086–1088, his soldiers were boiling soybeans as fodder for their horses when they were attacked; they hastily bundled the hot beans into straw bags, and by the time the bags were opened days later the beans had fermented into something sticky and stringy. The soldiers ate it, liked it, and the food caught on. A second legend reaches even further back, to Prince Shōtoku (574–622), who is said to have wrapped leftover boiled soybeans in straw for his horse, only for people to discover the fermented result was good to eat.

These stories are charming and widely retold, but there is no firm evidence that either episode actually produced natto, and historians treat them as folklore. What they do capture — and this part is grounded in real microbiology — is the central role of rice straw. The bacterium responsible for natto, Bacillus subtilis var. natto, occurs naturally and is especially abundant on straw. For most of natto's history, wrapping warm cooked soybeans in straw was exactly how the fermentation was started, because the straw carried the microbe. The legends, in other words, dress up a genuine fact in story form: straw and warm beans really are how natto traditionally came to be.

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What "Natto" Means

The name itself preserves a clue to natto's past. Written with the characters 納豆, the word joins a character meaning roughly "to offer" or "to store" with the character for "bean" — so natto can be read, loosely, as something like "stored bean" or "offered bean." The traditional explanation, recorded in the Edo-period text Honchō Shokkan (1695), connects the name to the nassho — the kitchen or storeroom of a Buddhist temple — suggesting that fermented soybeans were prepared, stored, or offered in temple kitchens. The word "natto" is documented in a Japanese text dated to 1068, though scholars caution that the term may not yet have meant exactly the modern food at that early date.

This temple-kitchen etymology is the one most often repeated, and it fits the broader picture of fermented foods being kept and prepared in monastic settings. It is best understood, though, as the traditional and most widely accepted explanation rather than a settled certainty — the early history of the word is exactly the kind of thing that is hard to pin down. What the name does tell us reliably is that natto was, very early on, a food worth naming, storing, and writing about.

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From Rice Straw to Pure Starter Culture

For most of its existence natto was made the old way: cooked soybeans wrapped in rice straw, left warm so that the Bacillus living on the straw could do its work. That method is wonderfully simple, but it is also unpredictable — the straw carries whatever microbes happen to be on it, so quality and safety varied from batch to batch. The decisive modernisation came in the early twentieth century, during Japan's Taishō period (1912–1926), when researchers worked out how to produce a clean starter culture of Bacillus subtilis that could inoculate the beans directly, without relying on straw at all.

This was a genuine turning point. A defined starter culture made natto consistent, hygienic, and suitable for large-scale commercial production, and it is the foundation of the natto industry that exists today. It also, quietly, set the stage for everything that followed in this story: once the specific natto-fermenting Bacillus strain could be grown deliberately and reproducibly, scientists had a controlled way to study what that microbe actually made — including, decades later, the enzyme that would be named nattokinase.

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Dr. Hiroyuki Sumi and the 1980s Discovery

Here the story shifts from a thousand years of culture to a single laboratory. The discovery of nattokinase is credited to the Japanese researcher Dr. Hiroyuki Sumi, who had a long-standing interest in fibrinolysis — the body's natural process for breaking down blood clots — and was searching for substances that could dissolve the fibrin clots responsible for heart attacks and strokes. By his own widely repeated account, the key moment came around 1980: testing many foods against artificial fibrin clots, Sumi dropped natto onto a clot in a laboratory dish and watched it dissolve over the following hours. The fibrin-dissolving power of the sticky natto coating stood out sharply from the other foods he had tried.

Two honest qualifications belong here. First, accounts of exactly where Sumi was working at that 1980 moment differ — some say he was a researcher at the University of Chicago, others place the work in Japan — so this page reports the often-cited 1980 petri-dish observation as Sumi's own recollection rather than as a precisely documented event. Second, and more importantly, the firm, citable, peer-reviewed milestone is not 1980 but 1987, when Sumi and his colleagues published the formal description of the enzyme in the scientific journal Experientia (see the next section). The 1980 story is the memorable origin anecdote; the 1987 paper is the documented record. Both are presented here for what they are.

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Naming the Enzyme: Nattokinase

The landmark publication is well documented. In 1987, Hiroyuki Sumi, together with H. Hamada, H. Tsushima, H. Mihara, and H. Muraki, published a paper titled "A novel fibrinolytic enzyme (nattokinase) in the vegetable cheese Natto; a typical and popular soybean food in the Japanese diet" in Experientia. In it they reported that natto contained a previously undescribed enzyme with strong fibrin-dissolving activity, which they could extract with salt solution, and which had a molecular weight of about 20,000. It was in this paper that the enzyme received the name it still carries: nattokinase — literally, the "kinase from natto."

This is the point in the whole story where a real, named, datable scientific discovery takes place — and it is genuinely unusual for a natural-medicine ingredient. The Japanese people who fermented and ate natto for a thousand years did not "discover" nattokinase; they had no way to know an individual enzyme was responsible for any of the food's qualities. What Sumi and his colleagues did was different and specific: they isolated one molecule out of the food, measured its fibrinolytic activity, and gave it a name and a scientific identity. Tradition supplied the food; modern enzymology supplied the enzyme's name and address. (The word "vegetable cheese" in the title is simply the authors' way of describing natto to an international readership unfamiliar with it.)

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From Breakfast Bowl to Capsule

Once the enzyme had a name and a measurable activity, the path from food to supplement opened quickly. Natto's strong smell and slippery, stringy texture have always limited its appeal outside Japan — it is, famously, an acquired taste — so the idea of capturing its most studied component in a capsule, without the food's flavour, had obvious commercial appeal. Manufacturers learned to grow the natto Bacillus in controlled fermentation, then extract and purify the enzyme and standardise it not by weight but by fibrinolytic units (FU), a measure of how much clot-dissolving activity each dose contains. Nattokinase went on to become one of the most-studied natural fibrinolytic agents, and the subject of a large and still-growing body of research and patents.

It is important to keep the food and the supplement distinct even at the end of the story, because they are not interchangeable. Natto the food is famous as the richest dietary source of vitamin K2 (in the form known as MK-7), which is relevant to bone and cardiovascular health; nattokinase the supplement is the purified fibrinolytic enzyme and typically contains little or no vitamin K. The detailed modern evidence, dosing, safety considerations, and the vitamin K2 distinction are covered on the main Nattokinase page and in the Nattokinase Benefits articles; the cultural and culinary story of the food itself is told on the Natto page. This history has done its job once the two threads — an ancient food and a modern enzyme — have been told clearly and kept apart.

A closing caution, in keeping with the spirit of an honest history: that a food has been eaten safely for a thousand years tells us about the food, not about taking a concentrated enzyme extracted from it. Because nattokinase affects how blood clots, it is not a casual supplement — anyone on blood-thinning or antiplatelet medication, with a bleeding disorder, or facing surgery should speak with a clinician before using it. The history explains where nattokinase came from; it is not medical advice about whether to take it.

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Research Papers and References

The list below combines the key peer-reviewed papers behind nattokinase's discovery with curated PubMed topic-search links and reputable food-history sources covering natto's cultural origins. Historical sources (the 1695 Honchō Shokkan, the Minamoto no Yoshiie and Prince Shōtoku legends) are named in the article as traditional or legendary material rather than as modern citations. Author names, titles, and journals are given as plain text; only the stable DOI, PMID, or archive link is hyperlinked, and each opens in a new tab.

  1. Sumi H, Hamada H, Tsushima H, Mihara H, Muraki H. A novel fibrinolytic enzyme (nattokinase) in the vegetable cheese Natto; a typical and popular soybean food in the Japanese diet. Experientia. 1987;43(10):1110-1111. — doi:10.1007/BF01956052 · PMID: 3478223
  2. Chen H, McGowan EM, Ren N, Lal S, Nassif N, Shad-Kaneez F, Qu X, Lin Y. Nattokinase: a promising alternative in prevention and treatment of cardiovascular diseases. Biomarker Insights. 2018;13:1177271918785130. — doi:10.1177/1177271918785130 · PMID: 30013308
  3. Nattō (history, origin legends, etymology, and Bacillus subtilis fermentation). Wikipedia. — en.wikipedia.org/wiki/Nattō
  4. Natto (definition, origin, and regional history). Encyclopædia Britannica. — britannica.com/topic/natto
  5. Shurtleff W, Aoyagi A. History of Natto and Its Relatives. SoyInfo Center. — soyinfocenter.com — History of Natto
  6. Nattokinase — discovery, fibrinolytic activity, and history — PubMed: nattokinase fibrinolytic enzyme (Sumi, natto)
  7. Natto and Bacillus subtilis var. natto fermentation — history and microbiology — PubMed: natto Bacillus subtilis fermentation history

External Authoritative Resources

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Connections

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