Updated: Fact Checkers did not find the idea here wrong; they found “at the time of writing, there was no evidence” for this idea. Not that the idea is wrong or impossible. Only that there’s no evidence yet. Let’s get evidence! Let’s get data. See below! ⬇️
Based on prior studies on coronaviruses, mannose-specific plant lectins offer potential applications to prevent SARS-CoV-2 infection in COVID-19.
Status of mannose-binding lectin (MBL) and complement system in COVID-19 patients and therapeutic applications of antiviral plant MBLs
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7981598
Prevent SARS-CoV-2 infection in COVID-19?!?! Which lectins???
Leeks (allium porrum) have a mannose-specific plant lectin, allium porrum agglutinin (“APA”), that’s very potent against SARS coronaviruses.
The most potent lectin against the SARS-CoV-induced cytopathicity is the mannose-specific plant lectin isolated from leek (APA) with an EC50 of 0.45 μg/ml and a selectivity index of >222.
Plant lectins are potent inhibitors of coronaviruses by interfering with two targets in the viral replication cycle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7114093/
SARS-CoV (2002) is closely related to SARS-CoV-2 (2019) so I looked to see if the leek MBL might also be effective against SARS-CoV-2. A little bit of research into how MBL recognizes a pathogen tells us that the leek MBL is almost certainly very effective against SARS-CoV-2.
Scientists have identified the part of the spike (S) where MBL targets and binds to the SARS coronavirus. The MBL binding site on the spike is unchanged between SARS-CoV and SARS-CoV-2. On SARS-CoV, MBL binds to the SARS Spike (SARS-S) at a glycosylation site identified as N330. (Note: Please feel free to gloss over the word “glycosylation” as scientific mumbo-jumbo. It just means there are carbohydrates at that site for lectins, like MBL, to bind.)
The data indicated that MBL selectively bound to SARS-S and mediated inhibition of viral infection in susceptible cell lines. Moreover, we identified a single N-linked glycosylation site, N330, on SARS-S that is critical for the specific interactions with MBL.
A Single Asparagine-Linked Glycosylation Site of the Severe Acute Respiratory Syndrome Coronavirus Spike Glycoprotein Facilitates Inhibition by Mannose-Binding Lectin through Multiple Mechanisms
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919028
That N330 glycosylation site on SARS-CoV is conserved (meaning “retained unchanged” in biology) and remains present on SARS-CoV-2 (initially dubbed 2019-nCoV) where it corresponds to glycosylation site N343.
N330 corresponds to N343 in the spike glycoprotein of 2019-nCoV and is a conserved glycosylation site.
Structure analysis of the receptor binding of 2019-nCoV
https://www.sciencedirect.com/science/article/pii/S0006291X20303399
Same MBL binding site. Retained unchanged. Different name. (“What’s in a name? That which we call a rose, by any other word would smell as sweet.”)
As the key part of the SARS-CoV spike which MBL recognizes is retained unchanged on SARS-CoV-2, we can think of that conserved glycosylation site like a “viral signature”. Any MBL that recognizes the SARS-CoV signature (like the MBL in leeks) would almost certainly recognize the same signature on SARS-CoV-2. Scientists call these “viral signatures” a Pathogen Associated Molecular Pattern (PAMP) because, quite literally, these “viral signatures” are a pattern associated with pathogens. Unsurprisingly, MBL is a pattern recognition molecule for our immune system (Wikipedia).
The innate immune system is comprised of a sophisticated network of recognition and effector molecules that act together to protect the host in the first minutes or hours of exposure to an infectious challenge. The mannose-binding lectin (MBL) is an evolutionary conserved circulating host defense protein that acts as a broad-spectrum recognition molecule against a wide variety of infectious agents. Target binding triggers the MBL pathway of complement activation. MBL can be considered conceptually as an ‘ante-antibody’ because it has a role in mammals during the lag period that is required to develop an antibody response against infectious agents.
The mannose-binding lectin: a prototypic pattern recognition molecule
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7126801/
Here’s a picture for how MBL recognizes Pathogen Associated Molecular Patterns (PAMP) on SARS coronaviruses:
To put it very simply: Leek MBL has a triangular head that grabs onto a triangular viral signature at the top of the spikes on both SARS-CoV and SARS-CoV-2.
After the MBL grabs onto a SARS coronavirus (either SARS-CoV or SARS-CoV-2), …
MBL Activates Our Immune System To Eat It
When MBL, a “Mannose Binding Lectin”, grabs onto a SARS coronavirus, this activates our immune system via the Lectin Pathway to destroy the pathogen using a process known as Opsonization (Wikipedia).
The different activation pathways means that both antibodies and MBL can activate our immune system against SARS coronaviruses. And regardless of whether our immune system is activated by antibodies or MBL, “all three activation pathways initiates the opsonization pathway of complement”. Opsonization is key because that’s the step where our immune system tags pathogens for phagocytes to eat in a process called phagocytosis! (Nom-nom-nom! Pathogens are yummy!)
Using MBL to activate the Lectin Pathway against SARS-CoV-2 could help us end the pandemic because MBL in our innate immune system is A Faster Immune Response Against SARS-CoV-2 than our adaptive immune response.
Are you suggesting we eat our way out of this pandemic?
Yes! The science clearly says eating a vegetable (leeks) would feed our immune system with a MBL that hunts down SARS-CoV-2 for dinner. Didn’t your parents teach you to eat your vegetables because they’re good for you?
Let’s feast upon leeks so our immune system can feast upon the SARS coronavirus!
Lectins? What about Dr. Gundry and The Plant Paradox?
Have you heard about survivorship bias? Survivorship bias occurs when people focus narrowly on a problem. Dr. Gundry focused on the “dangers” of lectins highlighting how lectins in some foods cause auto-immune disease in some people. What do these lectins do when they are not causing problems? What do these lectins do for most people most of the time?
Dr. Gundry is famous for warning about the “hidden dangers” of lectins in healthy food. If you look closely though, Dr. Gundry explains the problem he sees is lectins in some vegetables we eat cause auto-immune diseases. An auto-immune disease is when your immune system decides to attack you. Basically, Dr. Gundry found that when some people eat some foods, some lectins are mistakenly targeting the immune system at the person. That is the definition of an allergy:
allergy (noun)
a damaging immune response by the body to a substance, especially pollen, fur, a particular food, or dust, to which it has become hypersensitive
Dr. Gundry didn’t find a Plant Paradox. Dr. Gundry is describing a Plant Allergy. An allergic reaction to a lectin in a vegetable that is targeting your immune system at you.
Do you see what I see? Dr. Gundry has already shown us that lectins in the food we eat will activate our immune system against what the lectins think are pathogens! As long as the lectin doesn’t see you as a pathogen (meaning you’re not allergic), these lectins are on the lookout for pathogens for us!
This is a simple friend or foe identification problem. Avoid foods with lectins that recognize you as a foe because you’re allergic to those. Lectins in vegetables that recognize real foes (e.g., SARS-CoV and SARS-CoV-2) are friends!
MBL, as a pattern recognition molecule of the innate immune system, provides a surveillance system both locally, at points of possible contact with the external environment, as well as systemically. In this manner MBL can contribute both to immunity from pathogens as well as maintenance of tissue integrity and homeostasis.
Mannose-binding lectin and the balance between immune protection and complication
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3259613/
Basically, eating vegetables helps our immune system recognize and fight off infectious pathogens; as long as you avoid eating vegetables you’re allergic to. Leeks are your friend against SARS coronaviruses; if you’re not allergic to leeks.
How many leeks to take against SARS?
A leek a week. Seriously. I did the math.
Scientists previously measured MBL levels in SARS patients vs people without SARS. The SARS infected patients had 0.636 μg/mL less MBL (average) which made them more likely to get infected by SARS coronavirus.
Based on how much MBL is in leeks (0.01 g MBL/ kg Leek) and an estimated half-life between 3 days up to 7 days, one medium leek (9 oz / 0.25 kg) per week provides a person with enough MBL to overcome that average in vivo MBL deficiency in SARS patients.
One medium leek a week provides an average person with enough MBL to go from the 😷 “Group sick with SARS” level up to the 😊 “Group without SARS” level.
Mind blowing, right? Eating this one leek vegetable once a week has the potential to end this pandemic by preventing SARS-CoV-2 infection.
Would leeks be effective against variants like Delta and Omicron?
Updated (2022–01–18): Almost certainly. Here’s my article explaining how the “viral signature” that MBL recognizes has remained the same from SARS-CoV (2003) through SARS-CoV-2, including all the major Variants of Concerns like Delta and Omicron.
Are there any other vegetables besides leeks that can help?
The science says leeks are the most potent and most effective that we know of so far. For now, stick with leeks (not garlic, onions, green onions, or scallions). I’ll explain more in another article.
UPDATE (2022–01–03): Fact Checkers ❤️
Hooray! This is getting noticed! Enough to get “fact checked”! And, their conclusion was “NO Evidence We Can ‘Eat Our Way Out Of This Pandemic’ By Eating Leeks”. I’m literally jumping for joy and couldn’t be happier at this result! Let me explain…
Mythbusters
Mythbusters is one of my favorite shows. They take an idea, create an experiment to test it, and then try it out. The outcome for each experiment in the show is either “Busted”, “Plausible”, or “Confirmed”.
Busted would have made me sad. Busted means that there is something else I didn’t know that completely prevents this idea from working. (And yes, it is very possible for me to have missed something because I come from an engineering & computer science background rather than anything related to biology or medicine. I know that there’s simply a lot I don’t know.) The fact checker and FDA reviewed this and they didn’t say it’s busted. Nothing in the fact check says this idea is impossible. The fact check only said there’s currently no evidence so it’s unproven. (Back to this in a bit.)
Confirmed was never going to be an option. I’ve presented a theory based on published & peer-reviewed science. The theory combines multiple references explaining: (a) how the mannose binding lectin from eating leeks should activate our immune system against what the lectin thinks is a pathogen, (b) the leek MBL recognizes SARS-CoV, (c) the leek MBL should recognize SARS-CoV-2 because MBL recognizes a part of the SARS spike that remains unchanged across SARS-CoV and SARS-CoV-2 (and variants), and (d) leek seems to have enough MBL to make a difference at reasonable levels of consumption. Based on what we know, the cited science gives us a roadmap for what should happen and what we can expect to happen. I present zero data and no experimental results so the fact checker marked this as “unproven” and said there’s currently “no evidence”. Confirmed is simply not an option until there is data and experimental results.
Plausible is the middle ground where I’m extremely happy to be at right now. Plausible means that this might work. The FDA and fact checkers reviewed this idea and they didn’t identify anything wrong.
The fact checkers even acknowledged the important role MBL has in innate immunity and did not dispute any of the prior studies on MBL. These imply our current understanding of MBL’s role in our immune system is accurate. I’m simply suggesting we try an obvious source for the MBL, leeks, because it was identified in the previously published science as the most potent lectin tested against SARS-CoV-2’s predecessor. There’s no evidence and this is unproven because nobody else thought to try it.
This is a huge win for me as some random internet person! Plausible (and not busted) means we should find a way to try this out!
I wonder… What if… Let’s Try!
My toddler watches a lot of Sesame Street and a theme in Season 51, “I Wonder, What If, Let’s try!”, is quite applicable here as a framework for problem solving. At the start of the pandemic, I wondered if there might be some food that could help us fight SARS-CoV-2. Garlic has compounds that help kill Giardia. Stinging nettle, commonly used for cold symptoms, has a lectin which inhibits RSV, a cold causing virus. And a 1,000 year old anti-microbial remedy made from wine, garlic and leek kills antibiotic resistant strains of Staphylococcus aureus. Maybe there’s a vegetable that could help us fight SARS-CoV-2?
“I wonder” is the brainstorming step. Wondering if there’s a vegetable that could help us fight SARS-CoV-2 led me to the research quoted above identifying leek having the most potent lectin tested against SARS-CoV. SARS-CoV is the predecessor to SARS-CoV-2 so leek seems like an obvious place to start. This led to more research and now asking…
“What if” the mannose binding lectin in leeks could help us fight SARS-CoV-2? Everything outlined above is reasonable based on what we know so far. The key is putting information together and asking questions to come up with new ideas. Dr. Gundry’s work demonstrates that eating vegetables allows their lectins to activate our immune system. This is problematic when the lectins think you are a pathogen. But what if we eat a vegetable with a lectin that should target SARS-CoV-2 (and not you)? 🤔
If everything works as expected based on our scientific understanding of Mannose Binding Lectins and innate immunity, then eating leeks should feed our innate immune system with a MBL that hunts down SARS-CoV-2 for dinner. The science is quite clear on the role Mannose Binding Lectins have in our innate immune system and that the lectins we eat can activate our immune system. If things work the way the science says we should expect it to, then we have a new tool to fight SARS-CoV-2! If I’m wrong, we ate vegetables. (Either way, you should definitely eat your vegetables.)
“Let’s Try!” is the step where you take an idea and give it a shot. This is where we do an experiment and collect evidence.
“Currently, there is no evidence of leeks being associated with the prevention of COVID-19 infections.” — FDA
“No evidence” and “unproven” don’t mean wrong. These just mean nobody has tried it yet. So let’s try! Let’s get some evidence! I’ve put the idea out there. I’ve explained and cited the science behind how it should work. Nobody, neither the FDA nor the fact checkers, has said this idea is impossible or wrong. Everyone just wants to see data and evidence. I do too. I wrote this article to put the idea out there. Let’s try it and see what happens! If leek MBL works with our immune system as expected, then we can add eating vegetables (especially leeks) to our toolbox against SARS-CoV-2 alongside masks and vaccines.
The traditional approach for gathering evidence is a clinical trial. Google tells me the median cost of a clinical trial for drugs is $19M. That’s beyond my personal means. I’m reaching out on the Internet for help testing this theory out and getting evidence.
FDA — Want to help? Doctors? Nurses? Dietitians? Nutritionists? Professional, amateur or citizen scientists?
Let’s try to test this theory, see if everything works the way science expects, and collect evidence. Leek is just a vegetable and vegetables are good for you anyway. This theory implies vegetables are good for us in ways we’ve never appreciated by helping our immune system recognize pathogens.
Disclaimer: Opinions are my own and not those of Google.
