Covid-19: ABO Blood Type


The media was awash with reports of a preprint (not-peer reviewed) report that individuals who are blood type A might be at more risk of Covid19 infection than those who are type O. The study was conducted by scientists and doctors from cities across China including Beijing, Wuhan, Shanghai and Shenzhen. Medical researchers in China took blood group patterns of more than 2,000 patients infected with the virus in Wuhan and Shenzhen and compared them to local healthy populations. They found that blood type A patients showed a higher rate of infection and they tended to develop more severe symptoms.

One of the many media reports

While the researchers said the study was preliminary and more work was needed, they did urge governments and medical facilities to consider blood type differences when planning mitigation measures or treating patients with Sars-CoV-2.

“People of blood group A might need particularly strengthened personal protection to reduce the chance of infection,” wrote the researchers led by Wang Xinghuan with the Centre for Evidence-Based and Translational Medicine at Zhongnan Hospital of Wuhan University.

There is a long evidence-based history that linking the ABO blood types (A, B, AB and O) with specific differences in susceptibility to a wide range of infectious illnesses, including smallpox, plague, cholera and influenza. Although most speculation calls research to identify some aspect of the difference between the cell antigens that characterize the physical manifestation of ABO blood type, it is much more likely that the cause behind the blood type differences lay instead with the opposing blood group antibodies and not the antigens.

The science behind the relationships between the ABO blood groups is simple enough:

  • Blood type A has the ‘A’ antigen (a sugar known as GalNac) and makes an antibody against blood type B
  • Blood type B has the ‘B’ antigen (a sugar known as Gal) and makes an antibody against blood type A
  • Blood type AB has the ‘A’ antigen and the ‘B’ antigen; they do not make antibodies against any other blood types (universal receiver)
  • Blood type O does not have a recognizable antigen (think of ‘O’ as ‘zero‘); they make antibodies against both A and B blood types (universal donor)

A study published in 2008 in the journal Glycobiology, ‘Inhibition of the interaction between the SARS-CoV spike protein and its cellular receptor by anti-histo-blood group antibodies.’ looked at the SARS virus and observed that the S (‘spike’) protein’s ability to adhere to cells expressing angiotensin-converting enzyme 2 (ACE2) was specifically inhibited by either monoclonal or human natural anti-A antibodies. This indicated that these antibodies may block the interaction between the virus and its receptor, thereby providing protection. They concluded that ‘the ABO polymorphism could contribute to substantially reduce the virus transmission, affecting both the number of infected individuals and the kinetics of the epidemic.’

Although these finding might be somewhat sobering for individuals (including myself) who are type A blood, I don’t think it’s time for drawing too many conclusions from the base observations.

  1. There are other reasons and factors that influence susceptibility to Covid19, including age, and other comorbidities, (hypertension, diabetes, cardiovascular disease, etc.)
  2. There is a great degree of variation between type O individuals with regard to the level (‘titer’) of their anti-A antibodies
    and in their class and quality
  3. Opposing blood type antibodies can come in two classes: the long-term ‘memory’ antibodies, known as IgG, and the ‘early’ antibodies, known as IgM.
  4. Of the two, IgM is the more powerful. It is a large molecule that floats in the bloodstream as a snowflake, then attaches to some microbial invader and changes shape to a ‘crab’. This crab shape allows the IgM antibody to clump (‘agglutinate’) pathogens directly, unlike IgG which acts more like a tagging signal to attract the immune system to the invader
  5. The reason that the protective effect was observed in type O and not type B (who after all also make anti-A antibodies) is that type B typically makes only the IgG class anti-A, which is probably less effective.
  6. Being type O on its own is not cause for wild celebration. In type O anti-A levels vary widely. They go down with age and are lower in urban dwellers when compared to rural dwellers, so just being type O in itself does not mean much

However, like any discovery with a true basis in reality, deep inside there is an engineering solution.

Many of you know, that I’ve researched lectins for many years. These are proteins that are made by many plants and invertebrates that react with sugars typically found in living organisms. My interest in lectins stemmed from the fact that many of these are in common foods and quite a few are specific for one blood type or another. For example, a lectin found in lima beans can agglutinate cells of a person who is either blood type A or AB but will not react with the cells of those who are B or O. In a way lectins are primitive antibodies, made by nature to protect delicate seeds, beans and other delicate ’embryos’ from fungi and other parasites until they can germinate and protect themselves. It’s at least possible to consider using food lectins to impart a somewhat ‘anti-A’ defense, even in people who are blood type A.

This is because lectins are extraordinarily specific molecules (the word ‘lectin’ was coined by its similarity to the Latin legere, which connotes a lock and key and translates into ‘I choose’.) We’ve known that certain lectins are ‘A like’ (have a preference for type A) but don’t actually clump type A cells. This is due to subtle differences in the structural specificity of their choice in the sugars they react with. For example, sugars can be the same with regard to their chemical structure, but differ in the spacial structure (ie in one sugar a hydrogen might ‘bend’ to the left, but in another might go to the right.) Same molecular structure; different shape.

These differences in lectin specificity are extraordinarily discreet. Let’s do something with this knowledge.

Readers of my books know that for type A I advocate a diet comprised of many plant based foods. These include:

  • Mushrooms (the supermarket ‘Silver Dollar’ type)
  • Soy beans, tofu, tempeh, miso
  • Fava and Great Northern Beans

It’s no coincidence that these foods all contain ‘A-like lectins,’ agglutinins that can act as pseudo anti-A antibodies. Also, as I wrote in a prior post, an entirely different class of lectins, known as as the ‘mannose-monocot class’ lectins have also been shown to block ACE2, the tethering dock for novel coronavirus. This class, which contains most of the Allium species (garlic, onion, shallots, leeks) also provide some pseudo-antibody support for type A, but can also be used by other blood types as well. The aforementioned lima beans would not be workable because they actually do clump type A cells, and in this case we want a near miss; a case of slightly mistaken identity.

Even type O can hot-rod their anti-A defenses, to hedge their defense a bit.

I were type O, I’d go into the closet and try to find that chondroitin sulphate I bought for my friend’s bum knee last year that didn’t work. chondroitin sulphate is actually polymerized GalNac which is the type A epitope (antigen). Stomach acid hydrolysis should yield free GalNac, which theoretically should induce an increase in anti-A antibodies. Sort of like using your gut to trick your immune system into thinking it received the wrong blood type in a transfusion, but the dose does make the poison I guess. The type O tips might even pimp up the antibodies for type B as well. Type AB should follow the tips for type A.

21 comments on “Covid-19: ABO Blood Type”

  1. Ray fritsch Reply

    Yet, according to almost every book reviewer, blood type diets aren’t ‘science based.’

    Thanks for the great info, doc.


    Thank you for this information, and for all the work you do. What do I do as an Ao Non-secretor? I’m also a GT5 Warrior. I’ve used your work to have a life worth living for 15 years, controlling the daily inflammation, without drugs, of rheumatoid arthritis and migraine, as well as a whole host of conditions, but I’m limited in the amount of extra phytonutricals and supplements I can afford on top of what I need on a normal day to remain functional. Any help you could give me would be greatly appreciated. With sincere thanks and gratitude. Pauline Bowerbank.

  3. Roxanne Godair Reply

    I am type O and at a higher risk for COVID-19 due to MAC and Bronchiectasis. Would the Chondroitin be a good supplement to help resist this virus? Do you recommend anything else that might help someone like me?
    Great article!

  4. Lauren Reply

    Thanks for the reminder about soy and mushrooms. I’ve heard people dismiss and discount onions, garic, etc., but I notice when I eat garlic in the winter I don’t get any incipient colds. I’ll keep your other recommendations in mind.

  5. Tsvetana Reply

    I have your book and I have studied extensively when I first purchased it in 1997. Quickly I paid attention to your chapter of the history of all blood types the personality and blood type a witch is myself.
    Great disappointment I had to eliminate certain favorite foods like milk gluten pepper banana… But I am feeling a much better because of that. In addition to this I have made a habit of including garlic and fresh onions in everything are you to use including large amounts of supplements of the category of vitamin C vitamin D3 zinc and NAC. I don’t know what the reason is but I have never had any major illness since I don’t have any flu I never had any not even a headache…. I don’t even take drugs for anything in my age category I should but I don’t because I don’t need it. i’m trying to say is I was influenced tremendously by your study in your research and I am sure it has affected thousands of others who have taken your book seriously, as I have. Thank you for this writing! …So far so good

  6. NAGANA Reply

    Informations très utiles, merci beaucoup pour l’aide que vous apportez à vos lecteurs.
    Je suis nouvelle et je n’arrive pas à savoir si je suis “sécréteur” ou “non sécréteur”.
    Je suis B+
    Bien cordialement

  7. Dana Myatt Reply

    I asked for it, I got it! That chondroitin sulphate “might even pimp up the antibodies for type B as well.” I’m gonna’ go pimp my antibodies right now! Thanks for the info. and the belly laugh, Doc!

  8. Valerie Reply

    Thanks for this information! I am curious what you might suggest for someone who is type O and allergic to sulfur? BTW 10 years ago I started adding fresh garlic cooked into my meals several times a week; I haven’t had a cold or flu in a decade. Not even one.


    Good luck getting tofu with the bulk-buying caused shortages of food here in the UK

  10. Charlotte Klein Reply

    Thank you Doctor. Useful as always! I read your book Eat right 4 your type in 1999 in Germany. It changed my life and well-being. I am blood type A. Freed me from allergies, sinuses trouble etc. I followed strictly the first two years, than more moderate. Only once seriously ill after emergency appendix surgery.
    Now 60+ I manage usually to follow the diet. Not on any medication. Have not seen a GP or hospital for myself since 2007. I strongly believe not getting this virus, even by living in London, UK.
    I feel utterly grateful to you and your research. My thoughts are with you.

  11. Rush Wayne Reply

    I appreciate the general strategy you are suggesting to boost anti-A. Not so sure, though, about the chondroitin idea, if it is actually broken down into GalNac monosaccharides by stomach acid. I believe monosaccharides are not in themselves antigenic. They generally have to be attached to something else, such as a protein, to raise antibodies.

    • Peter D'Adamo Reply

      True, indeed. Glycans make poor epitopes. I’ve perhaps oversimplified, or even worse, erred. I’ve always rationalized that some percentage of it probably winds up gut-biotransformed into some sort of glcyolipid or glycoprotein. Also, I don’t know for a fact what actually comprises the hydrolytic result of gastric chondroitin degradation. If derived from animal sources the GalNac may well already be in something of a glycoconjugate form.

  12. Christine Chan Reply

    Thank you so much Dr. D’Adamo – miss your in person lectures very much!!

    • Carolyn Kennedy Reply

      I am type A negative. Reading about the type A but also am curious if this makes any difference with neg factor changes the foods best for our health, as well as susceptibility for COVID.

  13. Chris Reply

    As soon as I saw the usual goons attacking Dr. Adamos ideas, (just like every other factual report about government power gone awry that they call “Baseless,” I knew there is valuable info to learn if I read his findings with an open mind. Too bad most “reporters” /”journalists” are now establishment YES people, afraid of losing their jobs if they report the truth!

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