Nattokinase: What the Research Actually Says About This Japanese Enzyme
Nattokinase is an enzyme extracted from natto, a traditional Japanese food made from fermented soybeans. It has been part of Japanese cuisine for over a thousand years, and researchers have been studying it seriously since the 1980s when Dr Hiroyuki Sumi, a Japanese scientist working at the University of Chicago, first isolated the enzyme and noticed what it did to blood clots in laboratory conditions. What he observed was striking enough that it's been attracting serious research attention ever since.
It belongs to a class of enzymes called serine proteases. Its primary action is fibrinolytic -- meaning it breaks down fibrin, the protein that forms the structural scaffolding of blood clots. That single mechanism is why nattokinase has attracted consistent attention in cardiovascular research over the past two decades, and why it sits in a different category to most of what passes for heart health supplementation.
What the Research Actually Shows
The cardiovascular research on nattokinase focuses on three main areas: blood pressure, blood viscosity, and fibrinolytic activity.
On blood pressure, a randomised controlled trial published in Hypertension Research followed 86 participants over eight weeks. Those taking nattokinase saw statistically significant reductions in both systolic and diastolic blood pressure compared to placebo. The effect was modest but consistent -- which is actually the kind of result worth paying attention to, because it's what real mechanisms tend to produce rather than outlier studies. View study
On fibrinolytic activity, a study published in Scientific Reports measured nattokinase's ability to dissolve fibrin directly, comparing it to plasmin -- the body's own clot-dissolving enzyme. Nattokinase demonstrated strong fibrinolytic activity, with researchers noting it could degrade multiple fibrin-related proteins that plasmin cannot. View study
On blood viscosity and flow, research published in the Journal of Cardiovascular Pharmacology examined the effects of nattokinase supplementation on markers of blood viscosity and clotting factors in healthy volunteers. Results showed meaningful reductions in plasma viscosity and fibrinogen levels over the study period. View study
The overall picture is of an enzyme working on multiple points in the coagulation and fibrinolysis pathway -- not dramatically, not as a replacement for medical intervention, but consistently and measurably.
What Nattokinase Does Not Do
This section matters, because a lot of supplement marketing in this space overclaims and it does the whole category a disservice.
Nattokinase is not a treatment for cardiovascular disease. It has not been studied as a replacement for anticoagulant medications. If you are on blood thinners, have a clotting disorder, or have been advised by a doctor about cardiovascular risk, don't add nattokinase to your routine without speaking to your GP first -- the combination of nattokinase and anticoagulant medication could amplify blood-thinning effects in ways you don't want.
The research base, while genuinely promising, is also still relatively limited in scale. Most studies have been small and short-term. Larger, longer trials are needed. What the research does support is nattokinase as a nutritional supplement with a studied and plausible mechanism of action for people approaching cardiovascular health as part of a broader diet and lifestyle strategy.
Who is Nattokinase Most Relevant For?
The people most likely to get something from nattokinase supplementation, based on the research profile, are those who have a family history of cardiovascular issues and are taking a proactive approach, anyone in their 40s or older who's focused on longevity and healthy ageing, people already following a clean diet and exercise routine who want to add targeted nutritional support, and anyone who's come across nattokinase through longevity-focused podcasts or research and wants a reliable quality source rather than whatever shows up first on a Google search.
It fits naturally into the same category as omega-3s and CoQ10 -- not a magic fix, but a well-researched tool with a sensible place in a long-term health strategy.
What to Look For in a Nattokinase Supplement
Not all nattokinase supplements are equal, and a few things are worth checking before you buy.
Source and purity matter. The enzyme should be derived from fermented soy and ideally certified organic -- non-organic sources may carry pesticide residues from the soy fermentation process.
Dosage is where people often get caught out. Research studies have typically used doses in the range of 2,000 FU (fibrinolytic units) per day. Check that the product uses FU measurement rather than just milligrams -- milligrams alone tell you nothing about how enzymatically active the product actually is.
Some formulations include prebiotic fibre like inulin, which supports gut health and may improve the environment for absorption. It's a useful addition rather than a gimmick.
The Feel Supreme Organic Nattokinase with Inulin ticks all of those boxes -- certified organic, sourced from fermented soy, paired with inulin for digestive support, and at 4,000 FU per capsule it delivers double the dosage used in most published studies. A 60-day supply at one capsule per day.
Shop Feel Supreme Organic Nattokinase with Inulin - €34.95
As a food supplement for adults. Not a substitute for a varied, balanced diet and healthy lifestyle. If you are pregnant, breastfeeding, under medical supervision, or taking anticoagulant medication, consult a healthcare practitioner before use.