Many of us experience fatigue that no longer truly resolves with rest, morning stiffness that takes time to dissipate, or extremities that remain cold even under several layers. These signals are not trivial. They often tell the same story: something is hindering circulation where blood should flow freely.
When inflammation becomes chronic, the body no longer completes the repair-dissolution cycle. Fibrin remains where it should have dissolved. Two enzymes act on these fibrin networks and the biofilms that inflammation leaves behind, which immunity struggles to reach: nattokinase and serrapeptase.
When Fibrin No Longer Clears
Fibrin seals and protects when the body repairs. The problem begins when inflammation never truly stops.
Repair cycles follow one another without a complete dissolution phase. What accumulates are dense networks that slow microcirculation where oxygen and nutrients need to pass.
This slowdown is not visible in a standard blood test. It is felt: slow recovery, areas of the body that remain cold or stiff, mental fog that settles without a clear reason. Slowed circulation means less oxygen reaching cells, fewer nutrients, and less waste removal.
The metabolic terrain gradually deteriorates. Long COVID is an emerging illustration: Thierry and his team observed fibrin microclots still present in some patients long after infection, in a context of inflammation that does not fully resolve.
This is not a single explanation for all post-viral symptoms, but a mechanism consistent with impaired microcirculation, similar to other chronic inflammatory terrains. When this terrain sets in, the body needs more than a break: it needs help to dissolve what has accumulated.
Nattokinase: Untangling the Congestion
Nattokinase comes from natto, a Japanese fermented soybean food. Its fibrinolytic activity directly degrades accumulated fibrin.
The first documented observations date back to Sumi’s work in 1987, which showed that this enzyme could dissolve fibrin clots in vitro. Fujita’s work in 1995 confirmed this effect in animal models. The documented fibrinolytic activity indicates that nattokinase participates in fibrin degradation mechanisms, without implying a mechanical dissolution of all deposits present in the body.
These mechanisms are consistent with improved circulation and tissue perfusion: a terrain where oxygen, nutrients, and metabolic waste removal could circulate better.
A randomized controlled trial conducted by Kim in 2008 documented a moderate decrease in blood pressure in participants receiving nattokinase, an effect consistent with improved circulation. Less heaviness in the legs, a sensation of warmth returning to the extremities, faster recovery after exertion: these signals are not spectacular, but they are measurable in daily life. The body regains a rhythm it had lost.
Serrapeptase: Piercing What Immunity No Longer Sees
Serrapeptase comes from a bacterium in the silkworm. Its action is not limited to fibrin: it also degrades the protein matrices that some bacteria build to protect themselves from the immune system.
These structures are called biofilms. They allow bacteria to resist antibiotics and immunity, a real clinical problem.
Selan’s work in 2008 showed that serrapeptase affects the invasion ability and biofilm formation in Listeria monocytogenes. More recently, Artini and his team documented in 2022 that this enzyme modifies the physiology of Pseudomonas aeruginosa, a problematic bacterium in cystic fibrosis patients.
Chronic infections that no longer truly respond to treatments can find a less favorable terrain. Immunity regains access to areas it could no longer reach.
Serrapeptase also acts on inflammation: it reduces the production of certain pro-inflammatory molecules, which can alleviate pain and edema in chronic contexts. When nattokinase and serrapeptase are combined, a complementary action is obtained: the former dissolves accumulated fibrin, the latter degrades biofilms and modulates inflammation. The synergy has not yet been proven by robust clinical trials, but the biological mechanisms converge.
Transient Reactions: What Some People Report
In field reports, some people describe signals that fluctuate rather than settle permanently: a temporary fatigue, pains that rise and fall, energy variations, sometimes the temporary reappearance of symptoms they thought were behind them.
These observations are quite common in field reports and discussions around chronic inflammatory terrain. They tell an experience, not necessarily the exact mechanism behind each signal. The scientific literature remains, for now, sparse on this type of reaction in this specific context.
Observation counts: noting what changes, at what pace, with what intensity, rather than concluding too quickly. Any symptom that worsens or settles is not automatically a “good reaction”: discernment consists of distinguishing what resembles a transition from what deserves another interpretation.
Many give up at the first wave of fatigue or discomfort; others push when they should slow down. Neither panic nor forcing: rhythm, hydration, and rest remain concrete markers on the terrain.
In case of worrying, persistent, or unusual symptoms (intense pain, high fever, shortness of breath, neurological signs), a medical consultation is necessary. What the body expresses deserves to be heard; it should not be interpreted too quickly on its behalf.
DISCLAIMER: This article is for informational purposes only and does not replace personalized medical advice. The information presented aims to clarify documented biological mechanisms; any decision about your health, especially with medical conditions, ongoing treatment, or scheduled surgery, should be discussed with a qualified healthcare professional.
Sources and References
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* Sumi H, Hamada H, Tsushima H, Mihara H, Muraki H. A novel fibrinolytic enzyme (nattokinase) in the vegetable cheese Natto; a typical and popular soybean food in the Japanese diet. Experientia. 1987.
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* Fujita M, Hong K, Ito Y, Fujii R, Kariya K, Nishimuro S. Thrombolytic effect of nattokinase on a chemically induced thrombosis model in rat. Biol Pharm Bull. 1995.
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* Kim JY, Gum SN, Paik JK, Lim HH, Kim KC, Ogasawara K, Inoue K, Park S, Jang Y, Lee JH. Effects of nattokinase on blood pressure: a randomized, controlled trial. Hypertens Res. 2008.
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* Tiwari M. The role of serratiopeptidase in the resolution of inflammation. Asian J Pharm Sci. 2017.
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* Selan L, Berlutti F, Passariello C, Comodi-Ballanti MR, Thaller MC. Protease treatment affects both invasion ability and biofilm formation in Listeria monocytogenes. Microb Pathog. 2008.
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* Artini M, Papa R, Pepi F, Selan L. Serratiopeptidase Affects the Physiology of Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients. Int J Mol Sci. 2022.
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* Thierry AR, Vigé D, Camus O, Buscail E, Lairez O, Edeas M, Resmini L, Buscail L, Gluais M, Benzaria A, Combe C, Chauveau D, Garnier A, Cristol JP. Circulating Microclots Are Structurally Associated With Neutrophil Extracellular Traps and Their Amounts Are Elevated in Long COVID Patients. J Med Virol. 2025.