Pick up almost any nattokinase supplement on Amazon (except Toku Flow) and check the label. You'll almost certainly see 2,000 FU per capsule. That number looks clinical. It sounds precise. And it's roughly 5x lower than the dose used in the research that made nattokinase worth talking about.

FU stands for fibrinolytic units, a measure of how much fibrin the enzyme can break down per unit time. The distinction matters because nattokinase activity is dose-dependent. 2,000 FU and 10,800 FU produce measurably different outcomes in clinical settings.

Where 10,800 FU Comes From

A 12-month study of 1,062 participants tested a daily protocol of 10,800 FU nattokinase combined with 180mcg Vitamin K2. The results: 39.1% improvement in coronary plaque health, 25% improvement in carotid artery flexibility, 17.6% reduction in total cholesterol. In that same study, they tested 3,600 FU per day and found that it was ineffective. The typical market dosage of 2,000 FU doesn't even reach this ineffective dose that the study measured.

The reason most brands dose at 2,000 FU is cost. Nattokinase at research-grade potency is expensive to source and expensive to formulate. Maltodextrin is cheap. A capsule that's 70% filler and 30% active ingredient costs a fraction of what a full-dose product costs to manufacture.

We dose Toku Flow at 10,800 FU per sachet. Full research dose. No filler. Chickpea-fermented, freeze-dried natto extract from South Korea. The same dose the research was built on.*

Reference: "Oral intake of nattokinase and vitamin K2 on atherosclerotic progression." 12-month, 1,062-participant clinical study. Results measured via coronary artery calcium scoring and carotid intima-media thickness.