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No scientific evidence for the claim that nattokinase can treat long COVID or “detox” COVID-19 vaccines

Posted on:  2023-03-24

Key takeaway

Nattokinase is an enzyme that was first isolated from natto, a traditional Japanese dish made of fermented soybeans. Research so far has shown that it can break apart proteins involved in blood clotting, which enables it to dissolve blood clots. While one study by Tanikawa et al. found that nattokinase could break down spike protein, the study was unrelated to long COVID and the experiments were performed in cells in the lab. Therefore, the results may not reflect what happens in the human body and also provide no information about its effects on long COVID.

Reviewed content


“Dissolution of Spike Protein by Nattokinase: Holy Grail of COVID-19 Vaccine Detoxification”; long COVID is caused by persistent spike protein in the body

Source: Facebook, Substack, Peter McCullough, Ben Lynch, 2023-03-19

Verdict detail

Incorrect: There’s no evidence that the spike protein generated through vaccination causes harm. COVID-19 vaccines haven’t been shown to be toxic, so it is unnecessary to “detox” from it.
Unsupported: The nattokinase study cited was performed only in vitro, not in people, so it provides no information about nattokinase’s effect in people with long COVID. The exact cause of long COVID still remains unknown. The assertion that long COVID is due to persistent spike protein and can be treated with nattokinase is unsupported by scientific evidence.

Full Claim

“Dissolution of Spike Protein by Nattokinase: Holy Grail of COVID-19 Vaccine Detoxification”; “Nattokinase may destroy the spike protein. It makes sense that it would [...] I don’t know any details or specifics of nattokinase in this situation. It just makes sense.”; long COVID persists due to persistent spike protein


On 21 February 2023, cardiologist Peter McCullough, who has become known for spreading COVID-19 misinformation during the pandemic, published a Substack post claiming that nattokinase is the “Holy Grail of COVID-19 vaccine detoxification”. As evidence for this claim, McCullough cited a study by Tanikawa et al. published in August 2022, which reported that nattokinase can break down the spike protein[1].

Chiropractor Ben Lynch later posted a screenshot of McCullough’s Substack post on Facebook. In the caption of the post, he claimed that nattokinase “may destroy the spike protein”. This claim, combined with Lynch’s allegation that the persistence of spike protein is the cause of long COVID, implied that nattokinase could be used to treat long COVID.

Nattokinase is an enzyme that was first isolated from natto, a traditional Japanese dish made of fermented soybeans, known for its powerful smell and slimy texture. Research performed on nattokinase so far showed that it can break apart certain proteins, including those involved in blood clotting[2,3], enabling it to dissolve blood clots. Some animal studies and small-scale human studies suggest that consuming nattokinase could offer cardiovascular benefits[4-6]. However, large-scale randomized trials are still required to determine its safety and the effective dose in people.

But neither McCullough nor Lynch’s claims about nattokinase’s effect on the spike protein of SARS-CoV-2 are adequately supported by the study from Tanikawa et al. Both claims also contain inaccurate assumptions about the COVID-19 vaccines and long COVID, respectively, as we will explain below.

Spike protein in the body is broken down over time post-vaccination; “detoxification” is unnecessary

McCullough’s claim presupposes that “detoxification” is necessary after COVID-19 vaccination because spike protein stays in the body and causes vaccine injury. This idea of COVID-19 vaccine “detoxes” became popular in late 2021, but medical experts pointed out that such “detoxes” are unnecessary and can even be harmful.

In the nattokinase study cited by McCullough, Tanikawa et al. performed their experiments entirely in cells in the lab; no trials in humans were conducted. The authors reported that nattokinase could break down spike protein, and hypothesized that nattokinase could be used to block infection by SARS-CoV-2, since the virus uses the spike protein to gain entry into cells to begin infection. The authors suggested that nattokinase could potentially be used to complement COVID-19 vaccination in the fight against the virus. The study didn’t mention using it to “detox” COVID-19 vaccines.

Misconceptions regarding the safety of spike protein generated through vaccination have been persistent, as these earlier Health Feedback reviews show. The earliest COVID-19 vaccines authorized for use in the U.S. don’t contain spike protein at all. These vaccines use mRNA or viral vector technology that leverage our own cells’ protein-making machinery to make spike protein. The mRNA from COVID-19 vaccines breaks down over time. The same is true of the non-infective virus used in viral vector vaccines, which breaks down after inserting the genetic material for making spike protein into our cells.

Various studies have reported that the spike protein from mRNA vaccination remains detectable for anytime between a few weeks to a few months. Using an ultrasensitive method to measure spike protein in mRNA-vaccinated individuals, Ogata et al. found that spike protein was virtually undetectable in the blood of most of the 13 individuals one week after the first dose of vaccine[7].

Another study by Roeltgen et al. reported the persistence of spike mRNA and spike protein in the lymph nodes of vaccinated people for up to 60 days after the second dose[8]. This may seem to conflict with the findings by Ogata et al., but this persistence isn’t unusual or unexpected when observed in the lymph nodes, since this is where antibody-producing cells (B cells) refine their ability to recognize pathogens. This is in line with the goal of vaccination: to generate robust immunity to a specific pathogen.

Clinical trials showed that the COVID-19 vaccines are safe

Clinical trials of the COVID-19 mRNA and viral vector vaccines showed that the vaccines are generally safe and effective at protecting people from disease[7-10].

Unlike earlier authorized COVID-19 vaccines, the Novavax vaccine, which was first authorized much later in the pandemic in July 2022, does contain spike protein that was produced in insect cells. But there’s also no evidence that the level of spike protein in the Novavax vaccine is harmful; clinical trials showed Novavax to be safe and effective[11].

On the whole, the bulk of the scientific evidence so far indicates that spike protein generated or introduced in the body through vaccination is generally safe.

However, it’s also important to acknowledge that scientists are still studying some of the more serious side effects associated with the COVID-19 vaccines and that new evidence could emerge later that might change our understanding about the safety of the spike protein.

For example, a study published in the journal Circulation in January 2023 observed that the majority of patients who developed myocarditis following COVID-19 mRNA vaccination had unusually high levels of spike protein in the blood that wasn’t bound to antibodies[12], suggesting that spike protein may be involved in the process. Post-vaccine myocarditis is a known, but rare, side effect associated with the COVID-19 mRNA vaccines and is predominantly seen in young men.

That said, it’s still unclear whether spike protein is simply a marker of the inflammatory process behind myocarditis or the causal agent of the myocarditis. Additional studies are still needed to understand how spike protein is related to post-vaccine myocarditis.

Overall, McCullough’s claim that people need to “detox” from the COVID-19 vaccination and that lingering spike protein post-vaccination is the cause of vaccine injury lacks reliable scientific evidence to support it. Moreover, people who take blood thinners or have blood clotting disorders are recommended to avoid nattokinase, as it can increase the risk of bleeding.

The cause of long COVID is still unclear; no evidence that nattokinase treats or improves long COVID

Long COVID, or post-COVID condition, develops in some people who were infected by SARS-CoV-2. It involves a range of health problems that can last for weeks, months, or years. Health problems associated with long COVID include fatigue, cognitive deficits, blood clotting disorders, and cardiovascular disease. The exact cause of long COVID still remains unknown, although one of the working hypotheses is that the virus SARS-CoV-2 persists in some people after the initial illness[13].

At the moment, no single treatment that is effective for all long COVID cases is available. However, treatments for specific components of long COVID can improve a person’s symptoms[13], such as intravenous immunoglobulin for immune dysfunction and anticoagulant drugs for abnormal blood clotting.

However, there is currently no clinical evidence that nattokinase is effective for treating long COVID in people, nor does the study by Tanikawa et al. constitute adequate evidence for the claim, since it wasn’t designed to study nattokinase’s effect on long COVID.


Science Feedback is a non-partisan, non-profit organization dedicated to science education. Our reviews are crowdsourced directly from a community of scientists with relevant expertise. We strive to explain whether and why information is or is not consistent with the science and to help readers know which news to trust.
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