You might recall a Chinese study from a few years back claiming a sizable effect on atherosclerotic plaque for supplementation with nattokinase. The result was a 36% reversal in plaque size, which is several times larger than can be reliably achieved with approaches such as statins and their successors, drugs that lower blood cholesterol. The dose was 6000FU/day for 6 months. My attention was recently drawn to the publication of results for a US study using dose of 2000FU/day for several years. In that study, there was no effect on the progression of atherosclerosis, and certainly no marked reversal.
Medicine in general has a serious replication issue, in that all too many claimed results evaporate when a more rigorous study is undertaken. One only has to look at the NIA Interventions Testing Program to see many claims of longer mouse life spans refuted by more careful work. Problems with replication and study quality are particularly the case for clinical work conducted outside the US and Western Europe. One can find a great many researchers in wealthier nations who are immediately and reflexively skeptical of studies in their field that were conducted in other parts of the world.
That aside, is this a question of different doses and patients with a different severity of disease? Perhaps, but when one sees data with this sort of inconsistency, it casts doubt on whether there is or can be an effect size large enough to be interesting. Nattokinase does appear to have an effect on mammalian biochemistry and cell behavior that could influence atherosclerosis, but that is never the point. Mechanisms are what they are, the question is always whether or not the effect size of manipulating the mechanism in this way, with this treatment, is large enough to pursue.
Described to be antithrombotic and antihypertensive, nattokinase is consumed for putative cardiovascular benefit. However, no large-scale, long-term cardiovascular study has been conducted with nattokinase supplementation. To determine the effect of nattokinase on subclinical atherosclerosis progression and atherothrombotic biomarkers. In this double-blinded trial, 265 individuals of median age 65.3 years, without clinical evidence of cardiovascular disease (CVD) were randomized to oral nattokinase 2,000 fibrinolytic units (FU) daily or matching placebo. The primary outcome was rate of change in subclinical atherosclerosis measured by serial carotid ultrasound every 6 months as carotid artery intima-media thickness (CIMT) and carotid arterial stiffness (CAS). Additional outcomes determined at least every 6 months were clinical parameters including blood pressure and laboratory measures including metabolic factors, blood rheology parameters, blood coagulation and fibrinolysis factors, inflammatory markers and monocyte/macrophage cellular activation markers.
After median 3 years of randomized treatment, annualized rate of change in CIMT and CAS did not significantly differ between nattokinase supplementation and placebo. Additionally, there was no significant effect of nattokinase supplementation on blood pressure or any laboratory determination. The results of this trial show that nattokinase supplementation has a null effect on subclinical atherosclerosis progression in healthy individuals at low risk for CVD.
The potential for nattokinase to "thin" blood and to reduce blood clotting by positive antithrombotic and fibrinolytic effects presents a unique opportunity to safely study such effects on cardiovascular disease and cognition. Using nattokinase under primary prevention conditions, the investigators propose to conduct a randomized, double-blinded, placebo-controlled trial to determine whether decreasing atherothrombotic risk can reduce the progression of atherosclerosis and cognitive decline. The investigators propose to randomize 240 healthy non-demented women and men to nattokinase supplementation or to placebo for three years. The primary trial endpoints will be measurement of carotid arterial wall thickness and arterial stiffness, early changes of atherosclerosis that can be measured safely by non-invasive imaging techniques.
At the conclusion of this trial, the investigators expect to have sufficient evidence as to whether reducing the propensity for thrombus formation and/or increasing fibrinolytic activity can prevent the progression of atherosclerosis and cognitive decline. These results will provide novel and important data that will be informative concerning primary prevention through the atherothrombotic pathway. Providing evidence for a reduction in atherosclerosis progression and cognitive decline with nattokinase is likely to shift the current clinical paradigm for the prevention of these chronic age-related processes. In addition, such evidence will serve to create a new field of discovery and opportunity for prevention of cardiovascular disease and dementia.