Natto is the only food source of nattokinase, but you can also buy it as a supplement. Research suggests that supplement intake is just as effective as consuming natto. Plant Breeding: “Improvement of soybean cultivars for natto production through the selection of seed morphological and physiological characteristics and seed compositions: https://cds-koch.de/website-title-nattokinase-kapseln-ihre-naturliche-unterstutzung-fur-die-gesundheit/