What is the Blood Type Diet, part 1

“One man’s food is another man’s poison.”


The Blood Type Diet was the major catalyst for me to become a naturopathic doctor, so I can say that it literally changed my life, both health-wise, but also career-wise. I first became aware of naturopathic medicine after reading Eat Right For Your Type, the best-known book by best-selling author Peter J. D’Adamo, ND. This was a major turning point for my health as the information in this book transformed me from a tired and cranky university student well on my way to being overweight (with chronic disease down the road) to an energetic and vibrant naturopathic doctor.

How it all began…

Have you ever wondered why the Atkins diet works for some people, while vegetarianism works for others? Dr. James D’Adamo noticed that some patients did well on vegetarian and low-fat diets while others did poorly. He began blood-typing his patients and a pattern began to emerge. Then, his son Dr. Peter D’Adamo researched his father’s theory while still a study at naturopathic college. He soon discovered a scientific basis for his father’s observations.

What is the Blood Type Diet?

Red blood cells

What is blood type?

There are four basic blood types: A, B, AB, and O. Each individual carries two alleles (one from each parent) that together determine blood type. Types A and B are dominant, while type O is recessive. Therefore, type O people carry two identical O alleles, while type A and B people can either carry two identical alleles (either both A or both B) or one dominant allele (A or B) and one recessive allele (O). Type AB people carry two dominant alleles (one of each of A and B), creating the fourth blood type.

There is also another commonly used blood typing system based on Rhesus factor. In this system an individual is either Rhesus positive or negative. Rhesus positive is dominant and Rhesus negative is recessive.

These blood types determine antigens (substances that serve as identifiers and stimulate production of antibodies) on your cells. Blood typing is used in transfusion medicine to determine which blood is safe to give each individual. Blood type O negative, being recessive, is the “universal donor,” meaning this type can be given to anyone without causing an immune reaction (antibody production). Blood type AB positive, being dominant, is the “universal receiver,” meaning this type can be given any type of blood without experiencing an immune reaction.

What does blood type have to do with food?

Blood type goes far beyond your blood to impact disease and nutrition. Your blood type antigens are not just in your blood, they are everywhere in your body, particularly the surfaces that interact with your environment. These include your digestive tract all the way from your mouth to your large intestine as well as your nasal passages and lungs. Because these blood type antigens are everywhere, they influence on how your body interacts with the food you eat via several mechanisms:

  • Lectins
  • Protective barriers in your body, including lining of your gut
  • Bacterial environment, including relevance to choice of probiotics
  • Stomach acid production
  • Intestinal alkaline phosphatase and processing of fats in your diet
  • Secretion of digestive enzymes and other substances

Blood type also influences other processes in your body and how you get sick:

Why should I eat right for my type?

“Your blood type is the key that unlocks the door to the mysteries of health, disease, longevity, physical vitality, and emotional strength. Your blood type determines your susceptibility to illness, which foods you should eat, and how you should exercise. It is a factor in your energy levels, in the efficiency with which you ‘burn’ calories, in your emotional response to stress, and perhaps even your personality.” (from the introduction to Eat Right For Your Type)

You literally “are what you eat” since all your cells, proteins, hormones, and neurotransmitters are constructed from what you put into your body. Therefore, what you eat is also your most powerful tool for preventing and healing illness. Eating right for your blood type is designed to optimize your digestive and immune health now to alleviate health issues as well as prevent future disease by protecting you against your unique susceptibilities. When you know your blood type, you are empowered to create an environment that is optimal for your type, including diet, exercise, and lifestyle.

A few of the major benefits to the Blood Type Diet:

  • Improve immune function, avoiding common infections
  • Lose weight by improving metabolism, increasing nutrient intake, and reducing toxic burden on your body
  • Prevent chronic disease, such as cancer, heart disease, autoimmune disease, diabetes, etc
  • Slow down the aging process by improving overall health
  • The majority of people come to the Blood Type Diet hoping to lose weight. While this is indeed a major focus of this system, the greater goal is improved physiological function when an individual eats the foods that are the best fuel for his or her system. The natural result of this improved function is weight loss, but also improvement in other health concerns (such as digestive disturbance, allergies, hormonal imbalance, pain and inflammation, mood regulation) and prevention of chronic illness (such as heart disease, cancer, diabetes).


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