blood type diet

The links between your blood type, personality, and diet, explained

Could blood type provide a key to wellness and even affect your personality? Canadian naturopathic doctor James D’Adamo and his son Peter D’Adamo think so. In Japan, extensive research on blood type and personality began more than 75 years ago. Blood type can be a valuable clue to understanding your own uniqueness.

Body Ecology Diet book

The Japanese have been studying the link between blood type and personality for over 75 years. 

To find out more about blood types, including what foods to eat and avoid, as well as ideal exercise, be sure to read The Body Ecology Diet.

Blood type As tend to have more sensitive constitutions. Too much stress may weaken their immunity more quickly than other blood types.

Today, it’s even more common to hear the Japanese ask your blood type than it is for Americans to ask your astrological sign.

Free download: Get the Body Ecology blood type ebook.

To the Japanese, both biology and genetics may determine personality

Almost all Japanese know their blood type, and for decades, blood typing has been used by employers when assessing job candidates, dating services for potential love matches, and even companies for marketing soft drinks and other products.

Donna Gates, the creator of Body Ecology, has a special relationship with Japan. She lived there from the ages of 12 to 15. She also studied with Lima Ohsawa, who founded Macrobiotics with her husband, George Ohsawa.

During her years of travel and study in Japan, Donna had an opportunity to learn first-hand the ways that the Japanese used blood types. This immediately caught her attention — especially because she had also become fascinated with the work of Dr. James D’Adamo several years earlier.

His theory focused on how blood type could indicate the foods and lifestyle choices most compatible for you.1 One man’s food is another man’s poison. After meeting Dr. James D’Adamo and reading his book, Donna began to question everyone about their blood type in an attempt to verify if the Blood Type Diet indeed provided clues to our individual uniqueness.

All of these years later, Donna is certain it does have merit and is worth our attention. In fact, when she began working with children with autism, she quickly saw that eight out of 10 of them were blood type A. An A herself, this clued Donna into more about the little bodies these kids were in and what their special needs were.

Knowing that blood is the most fundamental nourishment for our bodies, Donna believes that different blood types may react differently to certain substances in food.

Please reflect on this theory yourself and see if you don’t agree. While there’s limited research to date on blood type, it makes a lot of sense to look further into this theory. Blood carries the nutrients of foods into our cells, and clearly, not all blood is exactly the same.

While Dr. James D’Adamo’s theories were based on patient observation, his son Peter D’Adamo has tried to use a more scientific approach to the activity of lectins (proteins found in food). Peter found that eating the wrong lectins for your blood type may potentially cause issues like early aging and immune dysfunction.2

Donna credits much of the blood type information presented in The Body Ecology Diet to both James D’Adamo and Peter D’Adamo’s research.

But because of her own observations on blood type and her fortunate exposure to the Japanese theory on personality and blood type — as you will see in more detail in The Body Ecology Diet book — she doesn’t always agree with these two brilliant and creative men.

Try this fun experiment: Forward this article to your family and friends, inquire about their blood types, and discover how valid the below information on personality may be.

How does your blood type influence your personality?

There are four blood types: O, A, AB, and B, with blood type O being the most common.

Blood type A is where much of the research on blood types has been focused in Japan. In fact, roughly 57 percent of the Japanese are blood type A.3 Interestingly, the Japanese diet very much favors those with blood type A.

Here are some examples of blood type and personality, based on James and Peter D’Adamo’s work:

Blood type A.

  • Type As tend to be cooperative, sensitive, clever, passionate, and smart.
  • Often bottling up anxiety in order to get along with others, they may hold in their emotions until they explode.
  • Many As are tense, impatient, and unable to sleep well.
  • While As are capable of leadership positions, they may not take them because the stress isn’t good for their tightly wired systems.

In Japan, many As are in research. They have roles in discovering more about and refining science, economics, manufacturing, etc. Their research on microbes and other areas of medicine is some of the best and most meticulous in the world. They are perfectionists, to say the least.

Blood type As tend to have more sensitive constitutions. Too much stress may weaken their immunity more quickly than other blood types.

Low stomach acid is common among blood type As, even from birth. So, special care should be taken when eating animal proteins. Using digestive enzymes, like Assist Dairy and Protein, along with consuming fermented foods and drinks, is really a must for As.

It’s not surprising that fermented foods like miso and natto play an important role in providing easily digested protein in the Japanese diet. They also eat raw fish, which is much easier to digest than cooked.

Blood type B.

  • Type B individuals tend to be balanced — thoughtful like As and yet ambitious like Os.
  • They’re empathetic, easily understanding others’ points of view, yet often hesitate to challenge or confront.
  • Chameleon-like and flexible, Bs make good friends.

Peter D’Adamo found that while their immunity is strong, Bs are more prone to slow-growing viral infections, like lupus, MS, and chronic fatigue. They may also have problems with hypoglycemia and blood sugar, especially if they eat the wrong foods.

Blood type AB.

  • Type ABs tend to be very charming and popular.
  • They don’t sweat the small stuff and can be seen as spiritual — even at times a bit “flaky.”
  • Only a small percentage of the population is blood type AB.
  • There’s never a dull moment in an AB’s life, so if you find one for a friend, consider yourself lucky.

Like blood type As, ABs react to stress poorly. They’re stronger and more active than type As but need to pay attention to stress levels so they don’t compromise their immunity. Sometimes, it’s difficult to be an AB. ABs don’t like to fit into anyone else’s “boxes.” If they feel too confined, they’ll break out of that box and do things their own way.

When it comes to food choices, an AB must discover when they’re more B-like or A-like. For example, dairy foods, like milk kefir, can be excellent for ABs or not compatible at all.

Blood type O.

  • Type Os tend to be loners or leaders and are intuitive, focused, self-reliant, and daring.
  • Os handle stress better than other blood types and have strong immune systems (with potential for less susceptibility to COVID-19), a well-developed physique, and a physically active nature.4
  • Blood type Os tend to have sluggish blood flow and feel better with vigorous exercise for about an hour each day.

Obviously, many other factors influence your personality. Still, you may find these blood type theories quite fascinating. Do your own subjective research.

While Body Ecology believes that the blood type theory can provide clues to your diet and health, currently, there aren’t conclusive studies to support or deny the theory. The Body Ecology program offers a series of guidelines about your blood type so you can safely experiment.

Hopefully, you know your blood type. If not, it’s worth finding out (via your doctor, for example).

Keeping in mind the Body Ecology Principle of Uniqueness, blood type may be a way to modify Body Ecology guidelines for your own unique situation. Try it out for yourself and see what you think. We’d love to hear about your experiences.

Free download: Get the Body Ecology blood type ebook.


  1. 1. D’Adamo, J. (1989). The D’Adamo Diet. McGraw-Hill Ryerson.
  2. 2. D’Adamo, Peter, and Catherine Whitney. Eat Right 4 Your Type (Revised and Updated): The Individualized Blood Type Diet® Solution. New American Library, 2016.
  3. 3. Fujita Y, Tanimura M, Tanaka K. The distribution of the ABO blood groups in Japan. Jinrui Idengaku Zasshi. 1978 Jun;23(2):63-109. doi: 10.1007/BF02001790. PMID: 691841.
  4. 4. Kim Y, Latz CA, DeCarlo CS, et al. Relationship between blood type and outcomes following COVID-19 infection. Semin Vasc Surg. 2021;34(3):125-131. doi:10.1053/j.semvascsurg.2021.05.005.

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