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The nattokinase scam

Posted Aug 26 2008 4:17pm 9 Comments

A conversation about vitamin K2 commonly leads to confusion. Several people have asked about something called nattokinase .

The scientific data on the potential role of vitamin K2 deficiency in causing both osteoporosis and vascular calcification is fascinating. Along with vitamin D3, vitamin K2 may be an important factor in regulation of calcium metabolism. Supplementation may prove to be a major strategy for inhibition of vascular calcification.

Obtaining K2 in the diet is tricky, since it's present in just a handful of foods: egg yolks, liver, traditional cheeses, and natto. This is where the confusion starts.

Natto is a Japanese fermented soy product. I've had it and it's quite disgusting. Nonetheless, Japanese who eat natto experience less fracture. (A parallel study in heart disease has not been performed.) Natto is also a source of another substance called nattokinase .

Advocates (otherwise often known as supplement distributors) claim that nattokinase is a "fibrinolytic", or blood clot-dissolving, preparation that "improves blood flow, protects from blood clots, and prevents heart attacks and strokes."

Don't you believe it. This is patent nonsense. There are several problems with this rationale:

--Any oral fibrinolytic agent is promptly degraded in the highly acid environment of the stomach. That's why all medically used fibrinolytics are given intravenously. Drug companies have struggled for years to encapsulate, modify, or somehow protect protein (or polypeptide) products taken orally from degrading this way. They've never succeeded. That's why, for instance, growth hormone (a polypeptide) remains an injection, not an oral agent. An oral growth hormone, by the way, would sell like mad, so the drug companies would very much like to figure out how to bypass the degradative effects of stomach acid. One of the "researchers" behind the nattokinase claims boasts that he has single-handedly figured out how to protect the nattokinase molecule in the gastrointestinal tract. However, he won't tell anybody how he does it. Right.

--Fibrinolytic agents are extremely dangerous. In years past, we used to treat heart attacks with intravenous fibrinolytic agents like tissue plasminogen activator, urokinase, streptokinase, and others. They have fallen by the wayside, for the most part, because of limited effectiveness and the unavoidable dangers of their use. Fibrinolytics are "dumb": they dissolve blood clots in both good places and bad. While they might dissolve the blood clot causing your heart attack, they also degrade the tiny clot in your cerebral (brain) circulation that was protective. That's why fatal brain hemorrhages, bleeding stomach ulcers, and blood oozing from strange places can also occur with fibrinolytic administration. Believe me, I've seen it happen, and I've watched people die from them.

The idea that a small dose taken orally is healthy is ridiculous. Even if nattokinase worked, why the heck would you take an agent that has known dangerous and very real consequences?

Don't let this idiocy reflect poorly on the K2 conversation, which, I believe, holds real merit and is backed by legitimate science. This is symptomatic of a larger difficulty with the supplement industry: Insane and unfounded claims about one supplement erodes credibility for the entire industry. It gives regulation-crazed people like the FDA ammunition to go after supplements, something none of us need. You and I have to sift through the nonsense to uncover the real gems in this rockpile, real gems like vitamin D3, omega-3 fatty acids from fish oil, and, perhaps, vitamin K2. But not nattokinase.

Comments (9)
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I am a patient who has antiphospholipid syndrome.  I also have low factor VIII levels. Before this was diagnosed, in 2008, I suffered over 5 strokes (only 1 left me with some permanent damage, luckily) and countless tia's (am in my 50's and there was no other medical reason for me to be having stroke/tia). 

Because of the low factor VIII levels, my hematologist explained I was not a candidate for warfarin, however we tried heparin injections for 4 months.  My body could not tolerate them, it was explained to me that there was nothing which could be done for me.  (yes, I did have a second opinion).  

Several months later I was introduced to nattokinase at Allergy Research Group.  After much research, started taking 400 mg. daily, divided.  This was 2 years ago.  Since that time I have had one tia.  My hematologist is familiar with nattokinase, but will not support it, so I have had to leave her.  However I am working with my internist who does support it and gives me the proper blood tests; everything is in order.

Allergy Research Group addresses the question of stomach acid you bring up; they have printed much with the limited research which has been able to be done.  Before closing your book completely on this subject, perhaps you might look a bit further - many people are being helped by this where no other help is available.


Leigh Willmore

Lansing, MI 

Natto has been demonstrated in at least one clinical study to reduce blood clotting in a safe manner:

Nutrition Research. Volume 29, Issue 3, Pages 190-196 (March 2009). Nattokinase decreases plasma levels of fibrinogen, factor VII, and factor VIII in human subjects." Chien-Hsun Hsia, and others.

It seems to me that a critique of natto claiming that "it is ineffective because it does not pass through stomach acid in an active form" cannot simultaneously claim that it "is dangerous because it will prevent blood from clotting and thus cause a hemorrhage." Either it works or it doesn't. So far, the research I have seen suggests it works effectively and safely.

Nattokinase is hardly a "scam." I looked into this issue a little further and discovered that the fear that nattokinase is destroyed or inactivated by stomach acid is apparently unfounded, according to Mitchell Fleisher, MD., DHt., DABFM. He states that, "It is well absorbed and is not destroyed by stomach acid."

Source: "Cardiovascular Health: A Clinician’s Perspective ."


Thanks for your response.  I am, in effect, the guinea pig - for still so little is known about  antiphospholipid syndrome (aps).  What I do know is that after suffering countless tia's and apx. 7 small strokes, nattokinase appears to be working for me.  My aps counts do remain high, however.  I live a quiet and peaceful life, as much as possible, for this also is important.  Another aspect passed over by most mainstream western physicians.  Since the alternative is to take nothing, and the nattokinase has given me such a tremendous difference in lack of stroke/tia - I must wonder again why the FDA refuses to test this product.  Is it, as some have proposed, that there is just not the financial gain for the pharmaceutical companies?  

There, I have opened a Pandora's box.  Excuse me, you offered very good medical advice, I have gone beyond.  Again, thank you.  What matters, bottom line, is that I am able to get high quality nattokinase and take it.  However, I think of all the others who might also benefit from this, without the difficult side effects of warfarin or heparin, and I wonder.....


Nattokinase is an enzyme derived from "natto", a traditional fermented soy food popular in Japan. During the natto production process B. subtilis natto, a friendly bacteria, ferments boiled soybeans, releasing nattokinase. Best Nattokinase contains pure nattokinase enzyme with all Vitamin K removed.


I am not a scientist and can't really address the science (or lack thereof) behind the nattokinase claims.  However, I did successuflly and safely disolve a scary blood clot in my right leg by taking this suppliment.  I have had circulation issues in this leg for years, and within 1 week of starting nattokinase, the clot disappeared. 

Because of the risks of taking a drug such as cumidin, I elected to get as far away from my doctor and possible and treated the condition myself.  Maybe it was foolhardy, but I refused to subject myself to a hospital stay with an IV drip of what amounts to rat poison.  I didn't know if nattokinase would work or not, but since it was my own life I was experimenting with, I felt free to make that decision with not second thoughts.

 I am glad the blood clot went away, and furthermore, years of painful vericose veins and poor circulation in my legs also disappeared along with the clot.  Because of my own results, I really don't put much stock in the assertions of Dr. William D, the original poster.

As far as the claim that nattokinase is a scam, I have only this to say:  It took less than one $50.00 bottle of nattokinase to disolve the blood clot in my leg.  How much money do you think a bill for a hospital stay, attending doctors, and IV cumidin drip would have cost me?  Where is the real scam here? 

I have lost faith in several doctors who, if they were not taught about a certain

treatment, it is to be avoided.

I feel Dr. William D. fits in this catagory.

My varicose veins of 6 years have dissappeared from eating natto that I made at home for 3 months.  I have tried alot of foods and supplements, finally natto did it. The doctor said natto taste disgusting. This is a rather short-sighted statement. A creative chef can make natto into an incredibly tasty food. For example, natto in soups make the soup rich, smooth - there is no slimyness left. Natto made from pea can make a chewy desert with chocoloate sauce and honey that is so rich of nutrients and minerals. Natto with sauerkraut or kimchi also have no slimyness left.  You can find millions of people hooked on natto because it's addictive. I started making natto and eating it for 3 months... I look forward to eating it everyday.

Here is one of the studies that found nattokinase is effective taken in natto:


Nutrition. 2003 Mar;19(3):261-4.
Dietary supplementation with fermented soybeans suppresses intimal thickening.
Suzuki Y, Kondo K, Ichise H, Tsukamoto Y, Urano T, Umemura K.

Department of Pharmacology, Hamamatsu University School of Medicine, Shizuoka, Japan. 

Although soy foods have been consumed for more than 1000 y, it is only in the past 20 y that they have made inroads into Western diets. We investigated the effect of dietary supplementation with natto extracts produced from fermented soybeans on intimal thickening of arteries after vessel endothelial denudation. Natto extracts include nattokinase, a potent fibrinolytic enzyme having four times greater fibrinolytic activity than plasmin. Intimal thickening was induced in the femoral arteries by intravenous infusion of rose bengal followed by focal irradiation with a transluminal green light. Dietary natto extract supplementation was started 3 wk before endothelial injury and continued for another 3 wk after. In ex vivo studies, euglobulin clot lysis times were measured 3 wk after the initial supplementation. Neointima formation and thickening were also initiated successfully. The intima media ratio 3 wk after endothelial injury was 0.15 +/- 0.03 in the control group. Dietary natto extract supplementation suppressed intimal thickening (0.06 +/- 0.01; P < 0.05) compared with the control group. Natto extracts shortened euglobulin clot lysis time, suggesting that their thrombolytic activities were enhanced. These findings suggest that natto extracts, because of their thrombolytic activity, suppress intimal thickening after vascular injury as a result of the inhibition of mural thrombi formation.

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