15:10
nattokinase
The host argues that nattokinase — the blood-clot-dissolving enzyme isolated from fermented soybeans (natto) — is being overhyped on social media relative to its actual evidence base: while it plausibly lowers systolic blood pressure by 5-7 points and has a real anticoagulant effect, the flagship study driving the hype is a weak retrospective cohort, no randomized outcome trial (heart attacks, strokes, deaths) exists yet, so he personally does not take it and has not recommended it to family members with arterial plaque.
Natto is fermented soybeans, popular in Japan; in the 1980s scientists found natto extract dissolves blood clots in the lab and isolated the responsible enzyme, nattokinase, which later became a standalone supplement.
The host frames supplement evidence in three increasing levels of importance: (1) blood work/biomarkers, (2) structural changes like artery plaque, (3) hard outcomes (heart attacks, strokes, deaths) — and says this framework is 'translatable to any other supplement.'
In animal (mice/rat) studies, nattokinase dissolves clots, lowers cholesterol and blood pressure, and reduces artery-wall plaque — but the host notes animal results often don't translate to humans.
Nattokinase concentration is measured in FUs (fibrinolytic units); trials use inconsistent doses (2,000 to over 13,000 FU), which the host flags as a major confound across the field.
The clearest human effect is a modest reduction in systolic blood pressure: ~5 points at the common 2,000 FU dose (inconsistent across trials), and ~7 points in one trial using a higher 3,600 FU dose, suggesting a possible but under-tested dose-response relationship.
Effects on cholesterol, triglycerides, and blood glucose are inconsistent: no effect at 2,000 FU across trials, a significant reduction at 3,600 FU in one trial, and mixed/inconsistent results at higher doses (6,000-8,000 FU).
Nattokinase consistently slows blood coagulation markers, which the host describes as context-dependent: potentially protective against clot-driven events like heart attacks, but potentially worsening for people prone to bleeding, including hemorrhagic stroke.
A heavily-hyped Chinese retrospective cohort study (over 1,000 participants) reported large reductions in plaque, cholesterol, and triglycerides at very high doses (over 10,000 FU), with no benefit at ~3,000-3,600 FU — but the host stresses it's a one-off, unreplicated, non-randomized, no-placebo retrospective design, which he calls 'hypothesis generating' rather than clinically decisive.
A rigorous randomized, placebo-controlled trial at USC found no effect on plaque, artery wall properties, blood pressure, or cholesterol — but used a lower 2,000 FU dose, so it doesn't rule out effects at higher doses.
A small, lesser-known Chinese pilot trial (~30 participants per group, no placebo) compared 6,000 FU nattokinase to the statin simvastatin; both reduced plaque size, with nattokinase showing a somewhat stronger reduction — the host calls this more interesting than the hyped retrospective study but says it needs replication with a bigger, properly controlled trial.
No randomized outcome trials (measuring actual heart attacks, strokes, or deaths) exist for nattokinase yet; only a small, uncontrolled pilot study out of China in post-stroke patients reporting apparent recovery.
Host's overall evidence summary: nattokinase probably lowers systolic blood pressure by 5-7 points, has an anticoagulant/clot-busting effect, may reduce arterial plaque (not properly demonstrated), and its effect on hard outcomes is simply unknown.
The host explains why he wouldn't take it 'on the off chance it works': without outcome data, the true effect could be positive, neutral, or actively harmful, and he notes that drugs with promising preclinical data sometimes cause net harm in large trials due to off-target effects.
Reported side effects in trials so far appear minimal/benign; there are one or two isolated case reports of bleeding events in nattokinase users, but the host says causation isn't established from anecdotal case reports alone.
Host's caution: be careful with nattokinase if you have a bleeding propensity, are on blood thinners, or are about to have surgery — talk to a doctor first.
On using nattokinase specifically to lower blood pressure, the host says other interventions (diet, specific exercises, covered in his other videos) have stronger, better-evidenced effects, so for him it's still not worth taking nattokinase for that purpose.
Host discloses no financial conflicts of interest and that he doesn't sell any pills, prescription or otherwise; for his own heart health he takes pitavastatin and ezetimibe (not nattokinase), and some family members take rosuvastatin.
Separate from the supplement, eating natto as a whole food is associated across multiple studies with a lower risk of dying from heart disease and cardiovascular disease, an effect that survives adjustment for confounders like smoking and exercise.
Nutritionally, natto provides nattokinase plus vitamin K2, isoflavones, protein, and fiber, and is a fermented probiotic food.
Caveat: people taking the blood thinner warfarin should talk to their doctor before eating natto, as it could interfere with the medication.
The host's 'three levels of evidence' hierarchy (biomarkers → structural/imaging change → hard outcomes) is explicitly offered as a reusable lens for evaluating any supplement claim, not just nattokinase — and it's used to explain why a big, dramatic-sounding study can still be weak evidence.
He draws a sharp methodological distinction between retrospective cohort studies (looking backward at people who already chose to take something) and randomized controlled trials, explaining that retrospective designs are 'hypothesis generating' and prone to bias — which is precisely why the widely-hyped 1,000+ person Chinese study is, in his framing, weaker evidence than a much smaller randomized pilot trial most people haven't heard of.
He flags that the dose used varies enormously across the nattokinase literature (2,000 to over 13,000 FU), which undermines direct comparison between trials and makes it hard to know whether inconsistent results reflect a true null effect or simply underdosing.
He generalizes a cautionary principle beyond nattokinase: promising mechanistic/preclinical data can flip to net harm once tested in a rigorous outcomes trial, because drugs and supplements can have off-target effects invisible until a proper placebo-controlled trial is run.
The coagulation-slowing effect is framed as inherently double-edged — protective against thrombotic (clot-caused) events like most heart attacks, but a potential liability for hemorrhagic (bleeding) events like hemorrhagic stroke — meaning its net value is individual-dependent rather than uniformly 'good.'
He implicitly separates the question 'does this reduce plaque' from 'does this reduce heart attacks/strokes,' noting hard outcomes are 'the test of any pill' precisely because biomarker or plaque changes only matter to the extent they translate into fewer heart attacks, strokes, or deaths — a distinction a viewer comment echoes by noting plaque reduction could reflect either stabilization or destabilization depending on what's actually being removed.
«There's a popular supplement that's been getting a lot of hype on social media lately for heart health.»
— 00:00
«Full disclosure, I have no conflicts of interest. I don't sell any pills, prescription or not.»
— 01:05
«Personally, I don't take nattokinase. I think it's been excessively hyped on social media, but other views are possible.»
— 01:12
«In humans, we look at this in basically three levels. And by the way, this is translatable to any other supplement.»
— 02:22
«So, this could be good or bad, it depends on the context.»
— 05:04
«However, this study has enormous limitations. Number one, it's a one-off. These findings have never been reproduced.»
— 06:36
«these studies are a lot cheaper, a lot easier to run, but they're what we call hypothesis generating.»
— 07:24
«It's not really the type of evidence that you want to base a an important health decision on.»
— 07:33
«There is no outcome trials for nattokinase yet.»
— 10:19
«For me, the evidence on nattokinase seems really promising, really encouraging. I would love to see more trials on it properly powered and looking at these interesting outcomes and with the concentrations that matter. Until those are there, I'm personally not going to take it, and I haven't recommended it to family members who have plaque.»
— 11:08
«When we don't have outcome data, it could go in any direction. The outcome data could be positive, it could be neutral, or it could be negative. It could make things worse.»
— 11:37
«if they can only come up with a natto that doesn't taste like the inside of your gym bag, that would be great.»
— 14:57
Reception
Thoughtful, scientifically-minded audience appreciates the video's rigorous, evidence-based approach to supplement analysis, with respectful engagement despite moderate overall engagement.
The video's own bottom line, stated by the host: nattokinase's blood-pressure and anticoagulant effects look real but modest, its plaque-reduction evidence rests on a weak, unreplicated retrospective study, and with zero outcome trials to date he is withholding personal and family use until better-powered randomized trials exist.
15:10