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Blood Type O Diet: What to Eat and What to Avoid

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Blood Type O Diet: What to Eat and What to Avoid

The Blood Type Diet was developed by Dr. Peter J. D’Adamo, the author of the bestsellers “Eat Right for Your Type” and “Live Right for Your Type”. The diet is based on the principle that chemical reactions occur between the foods you eat and your blood type. According to D’Adamo, if you follow a diet designed for your blood group, your body will digest food more efficiently, you’ll lose weight, have more energy, and have a better general health.

According to D’Adamo, the blood type O diet is beneficial for people with O positive blood type as well as people with O negative blood type. Because blood type O is the most common blood type, I am going to look at the Blood Type O Diet and discuss what foods you should eat and what you should definitely avoid. At the end of the article you will find what critics say about this type of diet.


What exactly is Blood Type O?

Your blood group is identified by antigens and antibodies in the blood.

Antibodies are part of your body’s natural defenses against invading substances such as germs. Antibodies recognize anything foreign in your body and alert your immune system to destroy it.

Antigens are protein molecules found on the surface of red blood cells.

Blood group O has no antigens, but both anti-A and anti-B antibodies. As group O red blood cells don’t have any A or B antigens, it can safely be given to any other blood type group (A, B, AB).

What is the difference between O positive and O negative blood type?

Red blood cells sometimes have another antigen, a protein known as the RhD antigen. If this is present, your blood group is RhD positive. If it’s absent, your blood group is RhD negative.

A person with blood type O can have either O positive (O+) blood type or O negative (O-) blood type.2 The blood type O positive contains the RhD antigen but the blood type O negative doesn’t contain the Rhd antigen.3 The majority of people have O positive blood type.

What is the Blood Type O Diet?

According to Dr. D’Adamo, people with blood type O have more stomach acid which makes it easier to digest meals that contain protein and fat. Therefore, a blood type O diet contains more protein sources like red meat, poultry and fish.

However, a person with blood type O should limit their intake of grains, beans, and legumes and definitely avoid wheat and certain leafy vegetables. The reason for this is due to a compound called lectins.5

Lectins help your immune system to fight disease. However, according to Dr. D’Adamo, if you eat food containing lectins that are incompatible with your blood type, this can cause inflammation in the body and make the immune system become overactive, which can lead to autoimmune diseases.4

It has to be said that the blood type diet is not without its critics, and not all doctors agree with the health benefits of the Blood Type Diet. At the end of this article, I will discuss what some of the critics have had to say, and look at the evidence that Dr. D’Adamo has presented to refute their claims.

Let’s look at the best and worst foods for people with blood type O (O positive or O negative).

What to Eat and What Not to Eat on the Blood Type O Diet

People in the O blood group should follow a strict diet of certain foods. This means that it’s important to know what foods you can definitely eat and what foods are strictly off limits on the blood type O diet.


Lean Meats

For people in the O blood group, most lean meats that are organically fed are recommended to include in the diet.

The best types of protein sources that have a beneficial effect for people with blood type O positive and O negative are beef, veal, lamb, venison, and also most poultry. If you don’t eat meat, but prefer seafood there is plenty of choice of fish that you can enjoy. For example, cod, trout, herring, tuna, and mackerel are excellent foods to eat on the O blood type diet because they are a good source of iodine which is necessary for a healthy thyroid gland.

What meats to avoid

There are some meats that must be avoided if you are following the type O diet. These include most processed foods like bacon; in fact, any pork products are a definite no-no for people with O positive or O negative blood type. From seafood products, you should definitely not eat octopus and salmon roe (caviar) if you have blood type O.

So, from protein sources, there is a wide variety of meats and seafood to choose from for people in the blood O group.

Beans and Legumes

People who have blood group O need to be careful with the type of beans and legumes that they consume. Some beans are excellent for the O type blood group; however other legumes should be avoided. According to Dr. D’Adamo, people with O type blood often suffer from thyroid disorders and certain beans can either help the thyroid or slow down the thyroid.4

If you follow the blood type O diet you can include black beans, adzuki beans, and green (string) beans. Beans are also a valuable source of proteins and many beneficial nutrients. These types of beans help the thyroid gland to produce enough thyroid hormone for the body.

What beans and legumes to avoid


There are some beans and legumes which should be completely avoided by people who have blood type O. These are soybeans, lentils, green peas, and peanuts, including peanut butter. These foods are best avoided by people with O type blood because they are either harmful to you or provide no benefit at all.


Many fruits are beneficial for people who are in the O blood group. This is because some fruits help to regulate the stomach acid, which people with blood type O tend to have much more of.

Some of the best fruits for people with O blood group are plums, figs, and prunes because they help to lower stomach acid and keep your digestive system working effectively. Berries like raspberries, gooseberries, and cranberries can be eaten occasionally.

What fruits to avoid

Although most fruits are a good source of vitamins, there are a number of fruits that you should not eat if you are in the O blood group. The fruits to avoid in the blood type O diet are oranges, blackberries, strawberries, kiwifruit, and melons. This is because these negatively affect your metabolism or enhance toxins of other foods if you have O positive or O negative blood type.


There are many vegetables that are beneficial if you follow the O type diet. Leafy green vegetables are the best kind for people with O type blood because they are rich in vitamins and minerals and help to reduce blood clotting problems.

According to the blood type O diet, you can eat plenty of green leafy lettuce, kale, broccoli, okra, red peppers, and ginger root. These will help to keep you healthy and maintain your proper weight.

What vegetables to avoid

Other types of vegetables like cabbage, cauliflower, and Brussels sprouts, should definitely be avoided because they can affect thyroid hormone production. Also, you shouldn’t eat mushrooms and pickled vegetables if you are on the O blood group diet because they can cause inflammation in the digestive lining.


Dairy Products on the Blood O Diet

For people with blood type O (negative or positive), most dairy products should be avoided. This includes yogurts and most cheeses and eggs. However, small amounts of butter and mozzarella can be consumed on the blood type O diet.

Other Tips for the Blood Type O Diet

Apart from what I’ve already mentioned about what to eat and what not to eat on the blood type O diet, there are some other dietary restrictions:

  • It is also advisable for people in the O blood group to completely avoid grains including wheat bread because the gluten in grains interferes with how the body processes insulin.
  • According to D’Adamo, rice, spelt, amaranth, quinoa and millet can be beneficial if you have O blood type.
  • Most alcoholic beverages and caffeinated drinks are a big no-no for people with blood type O. However, you can drink wine, water, and tea.

A person with O blood type who follows the blood type diet can deal with stress and anxiety better and reduce the risk of dependency on certain substances like drugs and alcohol. This is because the blood type O diet is claimed to balance levels of dopamine and other important brain chemicals.4

If you want to find out information on diets for the other blood types and the benefits that you can get from them, then please read my article on how to eat right for your blood type.

Is the Blood type O Diet for Everyone? What the Critics Say

If you conduct an online search for the Blood Type Diet, you will find that there is much controversy about the effectiveness of following a diet purely based on your blood type. Some people say that it only helps a person because it cuts out processed food and increases the consumption of vegetables. Very often the words “debunked”, “skeptical”, and “quack” are used. However, is criticism of the blood type diet warranted?

In every case Dr. D’Adamo has refuted his critics’ claims with his own scientific proof. For example, he points out that one criticism is about the way lectins affect the blood. An article on the Weston Price Website dismisses the role that lectins have on the blood stream. However, as Dr. D’Adamo points out, on the very website that dismisses lectins, the author claims that you should avoid soy because of dangerous hemagglutinating lectins. So, it seems that there is some hypocrisy in the claims against the Blood Type Diet.

Dr. D’Adamo also points out that he is accused of offering very little scientific evidence for the Blood Type Diet. However, in his responses he always points to scientific research to back up his claims on the benefit of the Blood Type Diet.

Is the Blood Type O Diet suitable for you? It may not be for everyone, however, many people have benefited from following a diet according to their blood group.

Read my other article to learn what to eat for A, B, and AB blood types: How to Eat Right for Your Blood Type

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46 Responses to Blood Type O Diet: What to Eat and What to Avoid

  1. Mark Luxton says:

    I think there may well be diets better suited to different blood types. This makes perfect sense, especially if you understand that what we call human being is actually a mix of several species. I would imagine the blood groups originate from different species that likely had evolved with different diets. This matter is complicated though in that “humans” are an uneven mix. There must be type O’s, for example, that have more DNA from one species of hominid that others, which may mean their ideal diets would differ. Israelis clearly have a lot of Neanderthal DNA. The Irish clearly have a lot of Cro Mag DNA. If people from these two example groups have type O blood, would it not make sense that their ideal diets would differ?

    • tony says:

      evolved from what???

      We did not evolve but were created. Just like you r house or car or watch did not evolve but were built by a designer.

      • James says:

        God created all things. God designed the laws of the universe, we are not created individually in some lab or art studio. Intellectual design is evolution. Maybe our missing link in our DNA is God’s intervention as that is what separates us from animals and gives us our divinity.

      • Margaret Momparler says:

        Hi Tony,
        You might want to read The 12th Planet. Or watch Ancient Aliens. We have different Blood types and some foods are just not good for us. I’m an O Neg the oldest on the Planet and here 2 million before the A’s showed up to start farming. So beans, and some other plants are not good for us.

      • Margaret Momparler says:

        Think there was a bit of both creation and evolution. Because all blood types didn’t show up in the beginning. Just us lonely O’s were here. The others came later?

    • James says:

      Interbreeding has mixed up all the blood types though. Like you stated The Irish have Some cromag blood which would have RH negative blood type which is recessive to RH positive blood. So same rule with blood type genes and DNA. Only very isolated homonids/tribes have/had pure blood.

      • Margaret Momparler says:

        The Blood types are not all mixed up. There are basically 4 and have always been as they came along.

    • Athena Hooker says:

      It took ONE drop of blood (JESUS) to make us right with God who gave you your blood (life) in the first place. Eat what you want if it does not hurt you great, if it does stop.

      • JustLu says:

        Agree with your statement about God God did give us life, but it is our responsibility to take care of the life He gave us.
        Some foods will give us an immediate effect & if bad, then don’t consume. But some foods may cause long term effects, good or bad, that we may need to consider for a healthier lifestyle. We all need to sacrifice certain things to have better results if we want or need. Just as Jesus made sacrifices.

  2. Johann Fourie says:

    I definitely think it is worth the try and if it does not work as you feel, don’t carry on.
    To help the thyroid gland operate better I think weight problems will be less.

  3. jo MARTIN says:

    can you tell me about eating for your blood type, you only mentioned blood type O. How about the others. thank you

  4. Carla R. says:

    What if you are O-Positive, hypothyroid, and have PCOS and Insulin Resistance? Will this diet help one to lose weight? Thanks!

  5. rachel says:

    what happens if you are a vegetarian and blood type O s grains arent really permitted?

  6. Dement says:

    I don’t really know my blood type, but I love wheat. I was assigned type O and don’t really like the conditions.

  7. Gloria Zerr says:

    I am a vegetarian, I eat lots of vegetables, all my favourite vegetables, fruits and protein sources are no nos on this diet, leaving me very little to eat.

  8. Sabeen says:

    Ok, now I’m confused what to eat and whats not? Im o+ i have hypothyroidism, recently had postnatal pre eclampsia don’t know if it be fine after 6 week or become chronic?
    Which diet I should follow
    Or blood type
    I used to eat salmon thinking its good for me , I used to eat lentils, though good for health, now many i cant eat much red meat due to hypertension, should I die instead of following a diet?

    • Jenny Hills says:

      Hi Sabeen, the conventional medicine usually doesn’t believe in the blood type diet (and you can refer to the section about what the critics say in this article). I believe that conventional medicine will recommend you to follow a diet for hypertension, as pre eclampsia involves a high blood pressure. However in this diet you may not be able to consume some of the foods due to your hypothyroidism (your doctor will be able to give you more information about it). So you need to take in consideration both the high blood pressure and the hypothyroidism. Since I’m not a doctor or a certified health practitioner, I cannot give a specific advice. For more advice you will need to consult with your doctor or a dietitian.

      • Val says:

        It is too bad that they blatantly and rudely dismiss the blood type diet. It is nearly spot on for me. Outside of my allergies, there are foods that make me sick, and I always wondered why. Once I found the blood type diet, it all made sense. What’s interesting is that I am O+, and my husband is O-. The diet is applicable and beneficial to me, but it makes no difference to him. I am learning the why’s of the restrictions. Some restrictions are related to the way the foods are prepared or presented. I’m looking for a means to eat Brussels Sprouts. So, I’m wondering/researching if/how I can counter the negative effects by eating something that will enhance thyroid hormone production.

        • Jenny Hills, Nutritionist and Medical Writer says:

          If you have hypothyroidism (underactive thyroid), The common thought is to avoid cruciferous vegetables as they contain goitrogens. However does this doesn’t mean that someone with a hypothyroidism should completely avoid these goitrogenic foods. For people who manage their symptoms and restore their thyroid health back to normal, then eating these foods in moderation is probably fine, but it isn’t a good idea to eat them on a regular basis. Also goitrogens can be destroyed by cooking so you should also be sure to cook cruciferous vegetables instead of eating them raw if you have hypothyroidism.

  9. Awonusi Oluwatoyin says:

    If i mixed 3tsp of Apple cider vinegar with 1tsp of honey to drink, it is okay for type O consumption ? Is salmon fish good for type O .

    • Margaret Momparler says:

      I have always taken ACV because my brother worked for Dr Bragg. But I was reading today that O’s already have enough acid in our systems; maybe that is why we can digest meat. I wouldn’t eat veal though; that is sick baby beef and goes against my moral values.

  10. jd says:

    will energy increase with this diet? is kombucha good for type o positive/negative my fam is half of each. also what type of variance is there in the o type, some are capable of having dairy, grains,etc. without any bad repercussions..

  11. Nkuly says:

    Maize meal gluten free is allowed for group o

  12. SJ says:

    I completely agree with this article.All the food articles listed as a ‘no – no’ do not agree with me.However ,im a vegetarian ,so I cannot claim about the benefits of eating meat,but I can say with conviction that all the food items listed to avoid have never agreed with my digestion.Now that I know that this has been because of my blood type,atleast I can rest easy and not wonder ‘why’.
    I can also suggesr that its allright to go for brown breads and multigrain breads,and avoid the white breads.Go for bananas as they really help with the acidity.Never have too much coffee and yogurt .I also read somewhere that fermented foods agree with O blood group.
    All lentils and soups are very filling,except the ones listed.I also limit eggs to only once a day now and then.I also find that sometimes sugary drinks help alongside with meals for better digestion and feeling of fullness.I try to incorporate all the tastes like salty,sugary,bitter and sour in my food ,as I find that easy on my digestion.
    Hope I have been of help to someone who seem too confused as to what to eat.

    • Margaret Momparler says:

      You might want to skip the lentils? Most foods are from the New World and our blood seems to be from the Old World. You can eat fish. Bananas have to be careful; they are high in Potassium. Just read that almost all berries are good, but not strawberries and no blackberries.

  13. Lutchmee Ramsamy says:

    Hi,I am O-ve , have got vitiligo problem, have to lose weight , have lots of acidity, am confused of what to eat or avoid. please help me.

  14. peace says:

    Hi, I’m O- and all those alcohol and pork as you said are ‘a no go area’ I really dislike that before, don’t know maybe it’s due to my blood group or so, but let’s talk about the dairy I love eating egg and always enjoy going with yogurt, so how I’m I going to cope without it, can you please explain better if it’s not that dangerous to my health. thanks so much, will appreciate your response

    • Jenny Hills, Medical Writer and Researcher says:

      As you’ve seen from the article, the blood type diet has been criticized by other doctors and it may not be for everyone. As I’m not a doctor, I cannot give specific advice, and it is beyond my abilities to recommend it (or not recommend it) to other people.

      • Margaret Momparler says:

        I tend to trust searching for the truth. Doctors are not taught anything about nutrition. And Science changes over the years. So it is a search for how we feel. I just gave up coffee and I do feel better drinking Green Tea and Yerba Matte.

  15. Rhi says:

    I have PCOS, have a tendency to hyperactivity for a number of days almost always followed by huge fatigue and depressive phases… Some months PMS is wild and others barely occurs, also periods are and always have been all over the place.
    This diet, will it help me?

  16. Sampson Ofori says:

    The advice from the Doctor is really fantastic, i was admitted and after discharged a Dr. educated me on type o diet and it has help me a am appealing to the public to obey our Doctors advice to live better.

  17. Maame efua says:

    Want to loose weight too. Am an o-positive n I like salmond soo much. Will the blood type O diet help me loose weight?

    • V says:

      It said not to eat salmon eggs. So I would think salmon is ok. I had to read it twice because I was like, no… I love salmon.

  18. Barnacle Luffy says:

    Made it to 73. I have become very disillusioned with modern medicine and big pharma. What has worked for me is thinking positive. It seems like the subconscious only knows how to say yes. So, if I think that the outcome to a problem will be positive, my subconscious will eventually lead me to a solution; often quite different from the original possibilities. I recently came across a saying “If you make someone else responsible for your life you are a slave.” So, I have taken full responsibility for my health care. I have been lead to Endothelial Progenitor Cells or (EPC). It will be very interesting to see where this research will take me and of coarse the outcome.

  19. aaron drake says:

    if you doubt blood type diet works, you must first find out what your type is..10yrs ago i decided to try it out for one year. i had to give up my favorite foods..i’m afraid to gpeople believo back..i now get nausiated to even think of eating bbq ribs or any type of hot day i decided to drink me a cool mountain dew. hadn’t had one or any other carbenated drink for 2yrs..i got so sick i it came back up..and i use to drink 3 or 4 mountain dews a day.. and now at 77, few people my age when i tell them.. believe me, stick to eating according to your bloodtype.

    • Marie Grano says:

      agree aaron i’m nearly 84 years young and been doing o type eating for about 20 years and 3 years ago climbed a rather high mountain and don’t look 83… and can still dance for 4 hours,
      know around town as the dancing lady lol

  20. Melissa Martin says:

    I am o+ and insulin dependent diabetic how would this diet affect me? And some of what I see in the list I shouldn’t eat because of the diabetes’s please explain if this diet will help

  21. Michele Merkel says:

    This has helped and is very interesting!

  22. Ricardo says:

    Practically all the food recomended as NOT suitable for the 0 blood group, are the ones I like and which I eat daily. I am 94 years old, and caught Covid twice without any problem. I am also never ill, enjoy life and live alone. And so it is fortunate I did not read your recomendations when I was young :-).

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