IF YOU’VE NEVER heard of natto, you’re not alone. Outside of people eating a traditional Japanese diet, others aren’t eating much (if any) of the fermented soybean product. But, the supposed health benefits of the food are spiking popularity of its supplement counterpart: nattokinase.

“Japan has one of the longest average life expectancies in the world, and natto is widely considered to be one of the country’s secret weapons for longevity,” says
Kim Yawitz, R.D. Of course, then, people are taking nattokinase supplements for its similar longevity benefits.

Ahead, what you should know about nattokinase, and if it’s worth adding into your supplement stack.

What is nattokinase?

In the late 1980s, researchers isolated an enzyme in natto they believed to be responsible for many of its health benefits. The enzyme, dubbed nattokinase, was shown to break down fibrous materials, such as blood clots.

“In theory, this could help lower the risk of heart disease and hardening of the arteries (atherosclerosis),” Yawitz says. “Today, many people take nattokinase supplements hoping to improve their health without having to eat natto (which has a very distinctive taste and texture).”

Nattokinase supplements aim to harness the purported benefits of natto, says Chelsea Rae Bourgeois, R.D.N., L.D. A study involving almost 30,000 participants spanning over 16 years found that natto intake was associated with a lower risk of cardiovascular disease mortality in Japan.

In fact, there’s a growing body of research has been conducted on natto itself with promising results. “Many people in Asia believe that eating natto can help you live longer, and some studies actually support these claims,” says Yawitz. A large 2020 study found that adults who regularly ate natto were significantly less likely to die from cardiovascular disease than those who didn’t eat it.

That all said, experts agree that more research is needed to draw any definitive conclusions about nattokinase, specifically.

Nattokinase is sold in capsule, powder, and liquid form, with doses commonly ranging from 2000 to 7000 fibrinolytic units, says Yawitz. You may also find nattokinase in some multi-ingredient products labeled as heart health supplements, she says.

Do nattokinase supplements have any health benefits?

“Nattokinase really hasn’t been studied much in humans, so it’s hard to know if it’s worth taking as a supplement. So far, it appears to be safe and well-tolerated but not necessarily effective,” says Yawtiz.

A few studies have suggested that supplementing with nattokinase may help lower cholesterol levels and reduce the amount of plaque in the arteries. Still, these benefits were mostly seen in adults who were overweight, drank, or smoked and in those taking higher doses. “There’s not much evidence suggesting that nattokinase is beneficial for healthy adults at low risk for cardiovascular disease,” Rae Bourgeois says.

What are the risks of nattokinase supplements?

It’s important to note that there’s very little, if any, research on the effects of nattokinase on those with various chronic medical conditions, Rae Bourgeois says. The supplements can also cause an unsafe drop in blood pressure or exacerbate blood clotting disorders. “Before starting a nattokinase supplement, you should discuss potential risks with your doctor,” she says.

Nattokinase can also thin the blood, so it’s best to pass on supplements if you have bleeding disorders or take blood-thinning medications, says Yawitz.

Should I take a nattokinase supplement?

Despite the encouraging and emerging scientific findings, experts don’t think you should run out to buy this supplement quite yet.

“Until more human studies have been conducted, I’d pass on nattokinase supplements (unless your doctor recommends them, of course),” says Yawitz. “Most guys would probably benefit more from tried-and-true heart-healthy habits—like eating plenty of fiber, cutting back on alcohol, staying physically active, limiting added sugar, and having yearly check-ups.”

The FDA does not regulate dietary supplements, and research has not established a standardized dose for nattokinase supplements. But, if you like the taste of natto, it’s definitely a smart move to incorporate it and other fermented foods into your diet.

It bears repeating: you’ll always want to consult with your doctor or dietitian before adding a new supplement to your routine.