A three-year nattokinase trial found no effect on its main vascular measures.
A randomized study helps put the supplement claims in perspective.
By Happy Natto · Updated September 17, 2026
Illustrative editorial photograph. It is not an image from the cited study.Photo: Edward Jenner / Pexels
Participants without clinical cardiovascular disease were assigned nattokinase or placebo. Over approximately three years, the investigators did not find significant between-group differences in the reported carotid-thickness and arterial-stiffness measures.
What it does not establish
This tested a supplement in a particular low-risk population, not whole natto and not a replacement for prescribed treatment. A null result does not prove every dose or use is ineffective, but it does not support broad prevention promises.
How to use this entry
Open the original source for the full methods, analyses and context. The evidence label describes the type of source, not a universal score for the healthfulness of natto. We do not turn a product link into a medical recommendation.
