Nattokinase Benefits, Dosage & Side Effects Guide
, 5 min reading time
A plain-English guide to nattokinase benefits, dosage, FU strength and side effects, including who should avoid it.
Last reviewed: August 2026
Nattokinase pops up in conversations about heart health and healthy circulation, but the details, how much to take, what "FU" actually means, and who should be careful with it, often get glossed over. This guide walks through the practical questions people usually have. For background on what nattokinase actually is and how it's made, see the "What is nattokinase?" section of our Nattokinase Supplements Australia collection page.
Why Do People Take Nattokinase?
Nattokinase is commonly researched for its potential role in cardiovascular wellness and healthy circulation. It's a fibrinolytic enzyme, meaning it has been studied for its interaction with fibrin, and people often take it as part of a broader wellness routine focused on heart health.
People also take nattokinase as a practical alternative to eating natto itself. Natto, the fermented soybean dish nattokinase is derived from, has a strong flavour and sticky texture that isn't for everyone, so a capsule offers a way to explore the same enzyme without changing the diet.
It's worth being upfront about the state of the evidence: human research on nattokinase is still developing, and results are not consistent across all studies. Nattokinase should not be considered a treatment for cardiovascular disease, high blood pressure, or any other medical condition, and it isn't a substitute for prescribed medicines or professional medical care. Anyone managing a diagnosed heart or circulation condition should talk to their doctor before adding it to their routine.
Typical Nattokinase Dosage
Most nattokinase products on the market, and most of the research behind them, use around 2,000 FU (roughly 100 mg) per day as the standard amount. This is the dose you'll see most often on Australian labels, and it's the starting point most manufacturers build their directions around.
Some studies have used considerably higher amounts. One safety study followed participants taking up to roughly 10,800 FU daily for a year and did not report adverse effects within that specific study. That doesn't mean a higher dose is automatically better or appropriate for everyone; it simply reflects what that particular research looked at.
We're not going to tell you what dose to take. The right amount depends on the specific product, its concentration, and your own health circumstances. Always follow the directions on the product label, and check with your doctor or pharmacist before starting, especially if you take any medication or have an existing health condition.
What Does FU Mean in Nattokinase Supplements?
FU stands for Fibrinolytic Units, a measure of how active the enzyme is, rather than a measure of weight. Two products can list a similar milligram amount but provide different FU activity depending on how they're manufactured and standardised, which is why FU is generally the more useful number to compare when shopping.
Here's how the common strengths compare:
- 1,250 FU and 2,000 FU: These are the most common strengths sold in Australia and cover the majority of nattokinase products on the market, including options from Solaray, Nutricost, NOW Foods, Dr. Murray's and others. Because there are multiple products at these strengths, it's worth comparing capsule count, price and format on our Nattokinase Supplements Australia collection page rather than picking on strength alone.
- 4,000 FU: A higher-activity option for people whose healthcare provider has suggested a stronger formula, or who simply want fewer capsules for the same overall intake. In our range, this is the Arthur Andrew Medical Nattovena, Pure Nattokinase, 4,000 FU.
- 10,000 FU: Some searches turn up mentions of 10,000 FU nattokinase products, but we don't currently stock one at this strength. If that changes, it will be added to our Nattokinase Supplements Australia collection, so that's the best place to check.
A higher FU number isn't automatically the right choice. Compare the label, the serving size and the manufacturer's directions before deciding, and don't assume that more is better without checking with a healthcare provider first.
Side Effects and Who Should Avoid Nattokinase
Nattokinase is generally well tolerated by healthy adults when taken as directed, but there are groups who should be cautious or speak with a doctor before starting:
- People taking anticoagulant or antiplatelet medication (such as warfarin, aspirin or clopidogrel): nattokinase's fibrinolytic activity means combining it with blood-thinning medication may increase bleeding risk. This combination should only be considered under medical supervision.
- People with bleeding disorders: conditions that already affect clotting can be compounded by a fibrinolytic supplement.
- Pregnant or breastfeeding women: there isn't enough safety data in this group, so it's best avoided unless a doctor has specifically advised otherwise.
- Anyone scheduled for surgery: nattokinase is typically recommended to be stopped at least one to two weeks beforehand because of its effect on clotting, though the exact timing should be confirmed with the surgical or medical team.
Mild digestive symptoms, such as stomach discomfort, have been reported occasionally, similar to other enzyme supplements.
What about the liver? Based on the currently available research, nattokinase is not generally considered to carry a liver toxicity risk at standard doses. Formal toxicology studies have not identified treatment-related liver damage, and reports of liver problems specifically linked to nattokinase are rare, isolated, and not well documented in the literature. That said, the liver plays a central role in producing the body's clotting factors, so anyone with an existing liver condition should check with their doctor before taking a supplement that affects clotting, as a general precaution rather than because of established evidence of harm.
Nattokinase vs Lumbrokinase: Are They the Same Thing?
No. Despite the similar-sounding names, nattokinase and lumbrokinase are different fibrinolytic enzymes from different sources: nattokinase comes from fermented soybeans (natto), while lumbrokinase is derived from earthworms. They're sometimes discussed in similar contexts because both have been studied for fibrinolytic activity, but they aren't interchangeable, and switching between them without checking the product label or speaking with a healthcare provider isn't recommended.
Compare Your Options
For a full side-by-side comparison of nattokinase strengths, formats and prices, browse our Nattokinase Supplements Australia collection. If you've also been wondering whether nattokinase is available at major Australian retailers, we've covered that separately in Is Nattokinase Sold at Chemist Warehouse, Woolworths, Priceline or Coles in Australia?
