Atherosclerosis is one of the great killers. Fatty deposits form in blood vessels walls, narrowing and weakening the vessels. Eventually something ruptures, and the result is a stroke or heart attack, but even absent that the condition can narrow vessels sufficiently to cause fatal coronary artery disease. Even with modern medicine, the condition is inexorable: the toolkit doesn't yet include a way to more than slightly reverse the buildup of these plaques, and medical professionals must focus on ways to incrementally slow the progression of atherosclerosis rather than delivering any true cure.
One of the side-effects of starting a company, Repair Biotechnologies, that is working on a way to reverse atherosclerotic plaque is that I've been doing a great deal more reading on the topic of atherosclerosis than I would otherwise have done in the course of writing Fight Aging! Thus I turn up interesting items from the past few years that I missed at the time because I lacked the context to understand why they were worthy of notice, or just didn't have the sort of focus on atherosclerosis that I have at the moment. The papers I'll share today fall into this category, providing evidence for nattokinase, a very simple and readily available supplement, to have a surprisingly large effect on atherosclerotic lesions in humans. After six months of treatment, a third of the lesions were removed.
All enrolled patients were from the Out-Patient Clinic of the Department of TCM at the 3rd Affiliated Hospital of Sun Yat-sen University. Using randomised picking method, all patients were randomly assigned to one of two groups, nattokinase (NK) and statin (ST) group. NK Group-patients were given NK at a daily dose of 6000 FU and ST Group-patients were treated with statin (simvastatin 20 mg) daily. The treatment course was 26 weeks. Common carotid artery intima media thickness (CCA-IMT), carotid plaque size and blood lipid profile of the patients were measured before and after treatment.
A total of 82 patients were enrolled in the study and 76 patients completed the study. Following the treatments for 26 weeks, there was a significant reduction in CCA-IMT and carotid plaque size in both groups compared with the baseline before treatment. The carotid plaque size and CCA-IMT reduced from 0.25±0.12cm2 to 0.16±0.10cm2 and from 1.13±0.12mm to 1.01±0.11mm, repectively. The reduction in the NK group was significantly profound, a 36.6% reduction in plaque size in NK group versus 11.5% change in ST group. Both treatments reduced total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG).
Nattokinase (NK), the most active ingredient of natto, possesses a variety of favourable cardiovascular effects and the consumption of Natto has been linked to a reduction in cardiovascular disease mortality. Recent research has demonstrated that NK has potent fibrinolytic activity, antihypertensive, anti-atherosclerotic, and lipid-lowering, antiplatelet, and neuroprotective effects. This review covers the major pharmacologic effects of NK with a focus on its clinical relevance to cardiovascular disease.
This effect size on atherosclerotic lesions is big enough to be suspicious, given that nattokinase is a supplement in common use, and the dose used is not outrageously large. We seem to be seeing a lot of that sort of thing these days, however; sometimes significance goes unnoticed, but equally sometimes it is an issue with the study that will be corrected later. It is hard to tell which without meaningful further effort. Does bisphosphonate treatment actually extend life expectancy by five years, and did this really did go unnoticed despite its widespread use in older people? Is fisetin actually a significantly effective senolytic compound in humans despite being widely used; did the very high senolytic dose in comparison to the usual supplement dose successful hide this property? How did nearly twenty years of earnest development and use of the chemotherapeutic dasatinib go past without anyone noticing that it killed enough senescent cells to improve health and measures of aging in mice and people? And so forth.
Over the past few decades, hundreds of millions of dollars (at the very least) have been spent on clinical trials to try to reverse atherosclerosis - to give existing repair systems in the body sufficient breathing space or increased capacity, allowing them to break down the fatty deposits that form in blood vessels. The sponsors of any of those trials would have been ecstatic to find a reliable reversal of atherosclerotic plaque that was half the size of that noted in the nattokinase trial here. One might take a look at a 2012 review paper that surveys the degree to which treatments at the time could achieve the goal of reversing atherosclerosis. A reversal of 15-20% in an unreliable fraction of patients was about the best that could be done. Most approaches were considerably less effective than that. Not a lot has changed in this high level picture since then.
At present the dominant approach to treatment of atherosclerosis is reduction of blood cholesterol, the cholesterol attached to LDL particles, or LDL-C. Statins are the long-standing approach, and are now being joined by even more effective treatments such as PCSK9 inhibitors. This slows down atherosclerosis by (a) lowering overall cholesterol, and thus freeing up some fraction of the macrophage cells that would otherwise have had to shovel it out of blood vessel walls, but more importantly (b) lowering oxidized cholesterol, which is very damaging to macrophages. When considering atherosclerosis and its treatments it is important to consider macrophages: they are drawn to the fatty lesions, and their task once there is to mine cholesterol from the lesion, ingest it, and hand it off to HDL particles that carry it back to the liver for excretion. This is called reverse cholesterol transport.
Atherosclerosis exists because macrophages become overwhelmed, mostly by oxidized cholesterol, but also by sheer volume of cholesterol, or by an overly inflammatory environment. They become agitated, call for help, become foam cells (some of which become senescent, causing further issues) or die. Most of a plaque is made up of the debris of dead macrophages, and the plaque itself is a self-expanding disaster area that calls ever more macrophages to their doom. Reducing the LDL-C slows down this feedback loop, but it cannot do much for existing plaques. There is some regression (the aforementioned 15-20% at best) because macrophages are given some breathing room, but plaques continue to grow at the new slower pace, and people continue to die.
There has been a considerable amount of work undertaken over the years on alternatives to lowering LDL-C. Researchers have tried all sorts of ways to improve the ability of macrophages to mine cholesterol and send it back to the liver. They have tried increased numbers of HDL particles (which are formed from APOA1 protein). They have tried altered forms of APOA1 found in some human populations that are associated with lower levels of atherosclerosis. They have tried the introduction of artificial HDL particles to swell the numbers. They have tried upregulation of the ABCA1 and ABCG1 proteins that perform the actual handoff of cholesterol molecules to APOA1. There is more in the same vein.
All of these things work pretty well in mice; the current best approaches produce 50% reversion of atherosclerotic lesions in animal studies. Yet all of those tried in humans, meaning the HDL and APOA1 approaches, have failed miserably in clinical trials. What this means is that there is something that the research community doesn't yet understand in the low-level detailed differences between human and mouse reverse cholesterol transport. That is a big roadblock for anyone turning up to propose some form of enhanced cholesterol transport as a therapy, even if intending to try one of the varied effective-in-mice approaches that hasn't yet been trialed in humans.
In this context, one can see that evidence for a common supplement to manage 36% reversion of lesions in humans is both welcome and jarring. It will certainly have to be replicated before many researchers in the LDL-C-focused side of the scientific community are likely to take it all that seriously. Any simple, easily obtained improvement should be welcome. Nonetheless, it is still only reversion by a third. The disease will still progress, and will still kill people. The research community has to do better than this.