What Is the Blood Type Diet?

The Blood Type Diet: Is It Right for You?

The blood type diet is based on the theory that your blood type determines the foods you should consume (and the exercise you should do) to achieve optimal health. The diet plan was originally developed by Peter D'Adamo, a naturopathic physician.

The idea behind the blood type diet is that eating foods with lectins (a type of protein) incompatible with a person's blood type can cause blood cell clumping, called agglutination, and result in health problems such as heart or kidney disease or cancer. However, there is a lack of scientific evidence to support these claims.

What You Can Eat on the Blood Type Diet

The blood type diet emphasizes certain foods and exercise plans for different blood types. Regardless of blood type, the diet emphasizes eating whole foods and minimizing the intake of processed foods. 

Type A Blood Type

According to D'Adamo, people with type A blood are predisposed to heart disease, cancer, and diabetes, and do better on an organic, vegetarian diet with calming, centering exercise, such as yoga and tai chi.

People with blood type A, who D'Adamo calls "cultivators," should follow a dairy-free, primarily vegetarian diet with a high intake of fruits, vegetables, grains, beans, legumes, nuts, and seeds.

Type B Blood Type

People with type B blood, according to D’Adamo, have a robust immune system and a tolerant digestive system and are more adaptable than other blood types. However, people with type B are more susceptible to autoimmune disorders, such as chronic fatigue, lupus, and multiple sclerosis.

D'Adamo recommends moderate physical exercise and balance exercises, along with a "well-rounded" diet for people with blood type B, or "nomads." People in this group should eat a highly varied diet including fruits and vegetables, grains, beans, legumes, meat, poultry, fish, eggs, and dairy, but avoid nuts and seeds.

Type AB Blood Type

People with type AB blood are more biologically complex than other types, according to D’Adamo. Based on this belief, these people supposedly do best with a combination of exercises and diets for types A and B, though meat should be limited.

It is believed that this blood type tends to have lower rates of allergies, but heart disease, cancer, and anemia are common. 

People with blood type AB, who D'Adamo calls "enigmas," can consume any food recommended for blood types A and B, although aiming for a mainly vegan diet is advised for this type.

Type O Blood Type

Based on the blood type diet theory, people with type O blood do best with intense physical exercise and animal proteins, while dairy products and grains may cause issues.

According to D’Adamo, gluten, lentils, kidney beans, corn, and cabbage can lead to weight gain in people with this blood type. Health conditions associated with type O include asthma, hay fever, other allergies, and arthritis.

People with blood type O, who D'Adamo calls "hunters," should stick to a dairy-free and grain-free diet high in meat and with a moderate amount of vegetables, eggs, nuts, and seeds.

What You Cannot Eat on the Blood Type Diet

No foods are completely forbidden on the blood type diet. However, not all foods are considered beneficial for different blood types, and processed foods are discouraged for everyone.

Tips to Prepare for the Blood Type Diet

There is no specific timing for meals or fasting periods required on the blood type diet. However, the plan advises against drinking water or other beverages with meals because it will dilute the natural digestive enzymes and make it more difficult to digest foods.

Pros of the Blood Type Diet

Like all fad diets, the blood type diet has positives and negatives.

• Encourages exercise: The blood type diet encourages exercise. Research shows that regular exercise combined with a healthy diet can lead to weight loss and promote weight management. However, there is no research to support the blood type diet as an effective weight-loss strategy.
• Emphasizes whole foods: Each blood type diet plan emphasizes choosing whole foods over processed foods, which is a healthy choice. The program also offers a wide variety of compliant foods for some blood types, which may make it easier to stick with.
• Can be a well-rounded choice: Although each blood type has its own set of dietary restrictions, the program is not a low-calorie diet with unhealthy restrictions on calorie intake. Plans for types B and AB are more well-rounded and can provide most if not all of the necessary nutrients for a well-balanced diet. However, the plans for types A and O restrict certain healthy food groups, which is not a smart long-term eating plan for many people.
  

Cons of the Blood Type Diet

Despite some potential benefits, the blood type diet is not recommended by health experts and has several drawbacks.

• Not effective: There is no research to support that the blood-type diet is an effective weight-loss strategy.
• Not based on science: Eating for your specific blood type is not rooted in science. The available research on the blood type diet includes a study published in the journal PLoS One in 2014. Anyone following the diets, no matter their blood type, may see benefits or no changes, according to the study.
• Requires unsubstantiated supplements: Although proponents of the blood type diet suggest the use of dietary supplements can help people following the diet plan meet their nutritional needs, such supplements are not regarded as a reasonable substitute for a healthy, balanced meal plan.
• Can be restrictive: Since the diets prescribed for blood types A and O are restrictive, there's concern that individuals following these diets may fail to achieve sufficient intake of many vitamins and minerals essential for health.
• Not backed by evidence: A research review published in 2013 showed no evidence to support any health claims associated with the blood type diet. In this review, scientists looked at 16 previously published reports on the blood type diet. Another 2020 review found no cardiometabolic benefits to be gained from the blood type diet.

Is the Blood Type Diet a Healthy Choice for You?

The blood type diet is based on theory; it isn't rooted in scientific fact and its effectiveness has not been proven in clinical settings. The overall plan emphasizes whole, natural, and unprocessed foods, making it healthier than some pre-packaged meal plans or meal-replacement plans.

The U.S. Department of Agriculture's 2020–2025 Dietary Guidelines for Americans provide recommendations for a balanced diet. The following nutrient-dense foods are considered part of a healthy diet:

• Vegetables of all types and dark, leafy greens (e.g., kale, spinach, broccoli, Swiss chard, green beans) 
• Fruits, especially whole fruits (e.g., apples, berries, melon)
• Grains, especially whole grains (e.g., quinoa, brown rice, oats)
• Lean animal protein (e.g., chicken breast, fish, turkey breast, eggs)
• Beans and legumes (e.g., beans, lentils, peas)
• Nuts and seeds (e.g., walnuts, almonds, sunflower seeds)
• Dairy products (e.g., reduced-fat milk, cheese, yogurt, as well as fortified soy-based dairy-free alternatives)
• Oils, including oils found in foods (e.g., olive oil, avocado oil, nuts, seafood) 

Depending on your blood type, this plan may or may not meet the USDA's definition of a healthy meal plan.

• The Type AB diet is the least restrictive and allows for the widest variety of foods to ensure adequate nutrition.
• The Type A diet prohibits meat and dairy, which have nutrients, namely protein, that can be found in other foods with careful planning.
• The Type B diet also offers a varied diet except for nuts and seeds and meets most of the USDA's requirements for a healthy eating plan.
• The Type O diet avoids dairy and grains, which are considered important parts of a healthy diet, according to the USDA. With careful planning, however, the nutrients found in grains and dairy can be made up by eating a variety of vegetables.

The blood-type diet does not suggest tracking or limiting calories. The USDA recommends a reduction of 500 calories per day for weight loss. On a 2,000-calorie diet, that's around 1,500 calories per day—but this number varies based on age, gender, weight, and activity level. Use this calculator to determine the right number of calories for you.

A Word From Verywell

While the blood type diet may offer some benefits in certain cases, following a health regimen that combines sensible calorie restriction and regular exercise is generally considered the most effective weight-loss strategy. If you're considering this diet plan for weight loss or overall health, talk with a doctor or registered dietitian first.

Remember, following a long- or short-term diet may not be necessary for you, and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.