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.