Nattokinase is one of many enzymes derived from the food product Nattō (boiled soybeans fermented by the bacteria Bacillus subtilis) and appears to have some direct fibrinolytic activity (fibrin degrading). It is thought to reduce the risk of cardiovascular events, but is fairly underresearched.
Sources and Composition
Nattō has a history as a food product used for pleasure (being well liked in Japan, but less favored in Western countries) and as a traditional remedy for cardiovascular diseases and fatigue. Nattō itself may contain multiple proteases, one of which (Bacillopeptidase F) also confers potent firbinolytic and anti-thrombus forming properties (which are the main claims of nattokinase). Nattokinase appears to be the most well researched of the proteases, and nattō is one of the few fermented food sources that have been found to contain fibrolytic enzymes (the others being Chungkook Jang, Douchi, and Tempeh).
Nattokinase is an enzyme produced via fermentation of boiled soybeans into the food product known as Nattō via the bacteria Bacillus subtilis, and can be produced outside of the food product via fed-batch culture fermentation. The enzyme is more related to the bacteria than the food product (despite being named after nattō) and has been able to be produced from shrimp tails.
It is sometimes referred to by the brandnames NSK-SD, NKCP, or Orokinase.
Nattokinase is an enzyme produced during the production of nattō using the bacteria Bacillus subtilis during the fermentation. It is not the only enzyme in nattō nor is nattō the only source of bioactive enzymes, but nattokinase appears to be the most popular enzyme derived from fermented foods.
Structure and Properties
The enzyme has a molecular weight of approximately 20,000-27.728Da and an isoelectric point (pI) of 8.6-8.7, and is a serine protease (inhibited fully by Neguvon and DFP). It has 275 amino acids in its structure, and has structural homology to subtilisins (69% homology with subtilisin Carlsberg, 85% subtilisin BPN, and 70% with subtilisin DY) with very high (99%) homology in the catalytic domain and fairly high (90%) homology in the binding pocket.
The above information is in regards to the enzyme traditionally known as nattokinase (Bacillus subtilis fermentation of boiled soybeans). Other enzymes produced from the bacteria Bacillus subtilis may also be referred to as nattokinases.
Nattokinase is a fairly large protein enzyme of the serine protease family, structurally related to the subtilisin class of enzymes.
It is stable at room temperature for up to 10 minutes at pH 6-12, but labile at pH 5 in isolation. Coincubation with gastric mucin, serum albumin, or boiled food products (meat and rice) increased stability so that no more than 7.5% activity was lost in acidic conditions. 30 minutes incubation at 40°C does not abolish the effects of nattokinase although 60°C for one hour appears sufficient to fully deactivate the enzyme, and deactivation is met with a complete loss of fibrinolytic activity.
When the enzyme is used in isolation, it is fully deactivated at the stomach's pH (1.2) within one hour. This may not fully abolish activities or supplemental nattokinase (as the bioactive peptides derived from the destroyed enzyme may have usage in blood pressure control) although the fibrinolytic effects of nattokinase are lost.
Resistance to acidic conditions using the nattokinase enzyme in isolation can be achieved via coating a capsule with methacrylic acid–ethyl acrylate copolymer or high molecular weight Na-γ-PGA. Enteric coatings also appear effective.
Nattokinase does not appear to be very resistant to acid and heat stressors in isolation (and could be degraded in the stomach) but appears to be able to be encapsulated with agents to reduce the rate of degradation. The fibrolytic effects of nattokinase are dependent on the enzyme being structurally active, with these effects being lost upon enzyme destruction
Nattokinase, in vitro, appears to be able to act upon protein aggregates common in Alzheimer's disease, which are known as amyloid fibrils.
Possible usage in treating protein aggregation in the brain of those with Alzheimer's, but the evidence is very preliminary and there is no in vivo evidence at the moment
Triglycerides and Cholesterol
6 months of nattokinase at 200mg (7,000 FU) daily has failed to significantly influence any lipid parameter (triglycerides, total cholesterol, or either of LDL or HDL cholesterol). This has been replicated in another study over 2 months.
No apparent effect on lipid parameters following oral ingestion in humans
Blood Clotting and Fibrolysis
Nattokinase has shown direct fibrolytic effects on Fibrin (1g Nattō equivalent to about 40CU of plasmin or 1600IU urokinase), plasmin substrate S-2251 (rate of 68.5nmol/min/mL), although a failure of fibrinolysis has been noted on urokinase substrate S-2444 and elastase substrate S-2484. Nattokinase, in vitro and in regards to fibrin, appears to have greater thrombolytic activity than serum plasmin.
The currently hypothesized mechanism of action is an inactivation of plasminogen activator inhibitor 1 (PAI-1) which results in a concurrently elevated level of tissue plasminogen activator (tPA). This has been demonstrated in serum following oral ingestion of nattokinase although with some interindividual variability (with oral nattokinase at 1,300mg thrice a day), with the increase in tPA being short lived for only 3 hours following oral administration. The increase in tPA, at least in vitro, has been noted with heat treated nattokinase that does not have any inherent fibrinolytic activity and is likely due to bioactive peptides.
Serum fibrinogen has been noted to be decreased in rats fed 2.6mg/g nattokinase in the diet (such a decrease not being seen with heat treated nattokinase). Oral ingestion of nattokinase for 2 months appears to reduce serum fibrinogen in humans in the range of 7-10% with similar reducing effects on factor VII (7-14%) and factor VIII (17-19%). There were no apparent differences in potency between healthy persons, those with cardiovascular disease states, or those on dialysis.
In vitro, nattokinase exhibits direct fibrinolytic properties that may degrade fibrin and reduce the risk of cardiovascular complications. This may be a mechanistic red herring, though, as this direct activity is lost upon destruction of the enzyme (heat treatment or digestion) and the peptides from nattokinase appear to increase levels of plasminogen activator which also has a fibrinolytic effect indirectly
Nattokinase first showed efficacy following oral administration in dogs, where thrombus was induced experimentally and anti-clotting effects confirmed via angiography (clot was lysed within 5 hours of oral ingestion). A small study in 12 persons given 12g nattō for 2 weeks (followed by a period where boiled soybeans were ingested for 2 weeks in place of nattō) noted that nattō consumption was associated with more fibrinolytic activity; this was later replicated with supplemental nattokinase at 1,300mg taken thrice daily.
One human intervention using a combination supplement (Nattokinase and Pycnogenol) in 186 subjects at high risk for deep vein thrombosis before a long haul flight (7-8 hours) noted that while five persons in placebo experienced a deep vein thrombosis and two experienced superficial thrombus (7.6% of the placebo group), no thrombus was detected in the intervention group. A decrease in edema (15%) was noted in the intervention group while an increase (12%) was noted in the placebo group.
There is insufficient human evidence using nattokinase in isolation and assessing thrombus formation to recommend its usage as an anti-clotting medication, although there does appear to be some promise. Dietary intake of nattō itself may confer a similar protective effect according to one preliminary study on the subject matter
Nattokinase appears to exert mixed-type inhibition on the ACE enzyme, and this is thought to be related not to enzyme activity but due to bioactive peptides from nattokinase. The ACE inhibitory potential is increased with heat treatment in accordance with this theory, as the IC50 of 800-1000mcg/mL (bacterial culture containing nattokinase and no peptides below 10,000Da) was increased to 200-300mcg/mL (heat treated bacterial culture). The bioactive dipeptides thought to be related to these effects were LY and FY, which were confirmed to be produced in high quantities. Another possible bioactive peptide is the tripeptide of Valine-Alanine-Proline which has been noted to be produced from soy protein and casein protein and corresponds to the amino acids 84-86 in the nattokinase sequence. An L-Tyrosine dipeptide (originally isolated from Royal Jelly) appears to also inhibit renin and lower blood pressure, and corresponds to the nattokinase sequence 262-263.
The byproducts of enzyme digestion (when the enzyme nattokinase is destroyed) appear to be bioactive di- and tripeptides, which have ACE inhibitory potential or may otherwise reduce blood pressure
In spontaneously hypertensive rats given nattokinase at 0.2 or 2.6mg/g of the diet for 3 weeks (or heat-treated nattokinase fragments at 0.2mg/g or 0.6mg/g) it was noted that both high dose groups were able to decrease systolic and diastolic blood pressure with the fragments trending to be more effective. No treatment was able to influence Renin or ACE activity in vivo, but the high dose heat treated nattokinase group noted a 47% reduction in angiotensin II levels after the experiment relative to control.
One human intervention using nattokinase at an oral dose of 2,000 FU per capsule once daily for 8 weeks in persons with hypertension (n=86) noted that nattokinase was associated with a reduction in systolic blood pressure of 5.55mmHg (95% CI of 0.57-10.5mmHg reductions) and diastolic blood pressure by 2.84mmHg (95% CI of 0.33-5.33mmHg) with a decrease in renin activity by 1.17 ng/mL/h.
Not many studies have been performed, but the one human study directly assessing blood pressure noted reductions in both systolic and diastolic blood pressure with low dose nattokinase (achievable via supplementation) along with a decrease in renin activity
A study in rats giving nattō (23g/kg diet, conferring 100,000 CU of nattokinase) for 3 weeks prior to and 3 weeks after a thrombus induction (photochemical thrombosis model) noted that supplementation was associated with improved Euglobulin clot lysis time (ECLT, indicative of fibrinolytic activity) and reduced intima cross-sectional area (indicative of protective effects on the endothelium following vascular injury). It has been noted that this dose is approximately 50-fold higher than commercial supplements.
May have endothelial protective effects, otherwise unexplored
One study assessing other fibrolytic enzymes found that adding 0-100ng/uL of one from Streptomyces omiyaensis (bacteria) to 100ng/uL of nattokinase did not interfere with nattokinase fibrolytic activity. 5ng/uL was able to enhance the activity of nattokinase fourfold and was said to be synergistic and worked by different mechanisms.
Byproducts of Streptomyces omiyaensis may be synergistic with nattokinase in regards to reducing clotting. This synergism is fairly underresearched
Red Yeast Extract
One study using 200mg nattokinase (7,000 FU) with or without Red Yeast Extract (RYE, 1,200mg) daily in two divided doses for 6 months in persons with untreated hyperlipidemia failed to show any efficacy of nattokinase on a serum blood panel while combination therapy was effective on LDL-C and total cholesterol (misleading as RYE itself is effective, and there was no RYE in isolation group). There appeared to be a reduction in uric acid associated with combination therapy (10.8%), but significant differences on this parameter were noted at baseline.
Insufficient evidence to support synergy between red yeast extract and nattokinase
Safety and Toxicology
One case study exists in a patient with cerebral microbleeds (stroke survivor) using daily Aspirin who also used 400mg nattokinase daily for a week. The patient experienced cerebellar hemorrhage attributed to the combination of two anti-clotting agents.
In one case study, pairing nattokinase with an anticoagulant was possibly related to the occurance of a stroke (which is normally the reason why pairing blood thinning agents is widely warned against).