Question explored with the scientific record
Nattokinase for IPF
The short version: there is no direct evidence that nattokinase treats or improves idiopathic pulmonary fibrosis, and the mechanism that would make it work is speculative.
The evidence you asked about does not exist in the retrieval. None of the eight records test nattokinase in IPF patients. The closest is a 2012 study showing that nattokinase (subtilisin NAT) inhibits angiotensin-converting enzyme (ACE) in a test tube, with heat-inactivated enzyme producing ACE-inhibitory peptides [8]. That is a lab finding, not a clinical result. ACE inhibition is a plausible pathway in IPF, because the renin-angiotensin system is involved in lung fibrosis, but plausible is not proven.
The rest of the retrieval describes IPF biology: surfactant abnormalities [1], BAL cell profiles [2], transcriptomic signatures in post-COVID fibrosis [3], monocyte biomarkers [4], an aging-informed model of IPF pathogenesis [5], and drug trials for PI3K inhibitors [6] and tyrosine kinase inhibitors [7]. None of these involve nattokinase. The tyrosine kinase inhibitor trial (BIBF 1120, nintedanib) is the closest comparator: it reduced FVC decline at 150 mg twice daily [7], but that is a patented pharmaceutical, not a food enzyme.
What would nattokinase need to do in IPF? It would need to reach active lung tissue, survive digestion, and modify the fibrotic cascade. The ACE-inhibition mechanism [8] is one small piece. Nattokinase also has fibrinolytic and anti-inflammatory properties documented outside this retrieval, but those are general effects, not IPF-specific. No trial has measured lung function, fibrosis progression, or survival in IPF patients taking nattokinase.
The safety profile of nattokinase is generally considered mild in food amounts, but IPF patients are often on anticoagulants or have fragile lung tissue. The bleeding risk from a fibrinolytic enzyme in a patient with pulmonary fibrosis is not zero, and no study here addresses it.
My call: nattokinase for IPF is an untested hypothesis with a plausible but thin mechanistic link. Confidence: low.
Sources used 8
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Surfactant abnormalities in idiopathic pulmonary fibrosis, hypersensitivity pneumonitis and sarcoidosis
This study investigates surfactant properties in bronchoalveolar lavage fluids from patients with idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, and sarcoidosis, revealing significant surfactant abnormalities in idiopathic pulmonary fibrosis compared to healthy con…
DOI: 10.1034/j.1399-3003.1999.14c14.x -
BAL findings in idiopathic nonspecific interstitial pneumonia and usual interstitial pneumonia
This study investigates bronchoalveolar lavage (BAL) findings in patients with idiopathic pulmonary fibrosis (IPF) to determine if they can distinguish between usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP), concluding that BAL findings do not e…
DOI: 10.1183/09031936.03.00105202 -
Unravelling the transcriptomic characteristics of bronchoalveolar lavage in post-covid pulmonary fibrosis
This study investigates the transcriptomic characteristics of bronchoalveolar lavage fluid in post-COVID pulmonary fibrosis (PCPF) patients, revealing distinct gene expression patterns and dysregulated pathways compared to idiopathic pulmonary fibrosis (IPF) and non-ILD controls.
DOI: 10.1186/s12920-025-02110-x -
S100A9/CD163 expression profiles in classical monocytes as biomarkers to discriminate idiopathic pulmonary fibrosis from idiopathic nonspecific interstitial pneumonia
This study investigates the expression profiles of S100A9 and CD163 on classical monocytes to differentiate idiopathic pulmonary fibrosis (IPF) from idiopathic nonspecific interstitial pneumonia (iNSIP), finding that specific monocyte phenotypes serve as potential biomarkers for…
DOI: 10.1038/s41598-021-91407-9 -
Revealing the Pathogenic and Aging-related Mechanisms of the Enigmatic Idiopathic Pulmonary Fibrosis. An Integral Model
An integrative, aging-informed model proposes that idiopathic pulmonary fibrosis (IPF) arises from a genetic architecture that destabilizes alveolar epithelial integrity, triggers distinctive epigenetic reprogramming, and drives aberrant epithelial–fibroblast signaling leading t…
DOI: 10.1164/rccm.201312-2221pp -
Evaluation of WO2013117503 and WO2013117504: the use of PI3K inhibitors to treat cough or idiopathic pulmonary fibrosis
This study evaluates two patent applications for the use of PI3K inhibitors, specifically GSK-2126458, in treating idiopathic pulmonary fibrosis and cough, highlighting their potential efficacy based on in vitro data and ongoing clinical trials.
DOI: 10.1517/13543776.2014.876411 -
Efficacy of a Tyrosine Kinase Inhibitor in Idiopathic Pulmonary Fibrosis
This phase 2 trial evaluated the efficacy and safety of the tyrosine kinase inhibitor BIBF 1120 in patients with idiopathic pulmonary fibrosis, finding that the 150 mg twice daily dose significantly reduced the decline in forced vital capacity compared to placebo, with fewer acu…
DOI: 10.1056/nejmoa1103690 -
Inhibition of angiotensin I converting enzyme by subtilisin NAT (nattokinase) in natto, a Japanese traditional fermented food
The study demonstrates that subtilisin NAT from natto inhibits angiotensin-converting enzyme (ACE) in vitro, with heat-inactivated subtilisin producing potent ACE-inhibitory peptides (LY and FY) that likely contribute to natto’s hypotensive effects, and mixed-type inhibition con…
DOI: 10.1039/C2FO10245E