What Is the Blood Type Diet?

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The blood type diet is an eating plan sometimes used in alternative medicine to promote weight loss and fight disease. Alternative medicine aims to recognize an individual’s biochemical uniqueness and tailor treatment accordingly. This plan is based on the theory that your blood type determines the foods you should consume in order to achieve optimal health.

The four different blood types are one marker that can theoretically be used to determine the right diet for your health and vitality. 

What Experts Say

"Basing a diet on your blood type is not evidence-based and restricts many healthy foods. Nutrition experts do not support or recommend this diet for achieving nutrition or health goals."

Kelly Plowe, MS, RD

Background

The blood type diet was developed by Peter D'Adamo, a naturopathic physician who theorizes that people respond to various foods depending on their blood type. The plan was introduced in his 1996 book "Eat Right 4 Your Type," which was updated with a 20th Anniversary edition in 2016.

The theory behind the diet is that eating foods with lectins (a type of protein) which are 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. 

D'Adamo also believes that a person's blood type affects their ability to digest various foods due to differences in digestive secretions associated with the different blood types. People who are type O, for example, are thought to digest meat well due to high levels of stomach acid.

By following a meal plan designed for your specific blood type, D'Adamo suggests, you can digest food with greater efficiency, avoid the negative effects of certain lectins, and—in turn—lose weight and enhance your overall health.

How It Works

The blood type diet emphasizes certain foods and exercise plans for different blood types. Regardless of blood type, the diet puts a focus on eating whole foods and minimizing the intake of processed foods. Here's a closer look at the prescribed plans:

  • Type A: 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.
  • Type B: 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. He recommends moderate physical exercise and balance exercises, along with a well-rounded diet. People with type B, however, are more susceptible to autoimmune disorders, such as chronic fatigue, lupus, and multiple sclerosis.
  • Type AB: People with type AB blood are more biologically complex than other types, according to D’Adamo. These people do best with a combination of the exercises and diets for types A and B, though meat should be limited. This type tends to have lower rates of allergies, but heart disease, cancer, and anemia are common. 
  • Type O: People with type O blood do best with intense physical exercise and animal proteins, while dairy products and grains may cause problems. According to D’Adamo, gluten, lentils, kidney beans, corn, and cabbage can lead to weight gain in this blood type. Health conditions associated with type O include asthma, hay fever, and other allergies, and arthritis.

    What to Eat

    No foods are completely forbidden on the blood type diet, though not all foods are beneficial for different blood types according to D'Adamo.

    Compliant Foods

    • Type A: mostly vegetarian—fruits, vegetables, grains, beans, legumes, nuts, and seeds

    • Type B: highly varied diet—fruits, vegetables, grains, beans, legumes, meat, poultry, fish, eggs, and dairy

    • Type AB: mainly vegan, but any foods recommended for A or B types may be consumed

    • Type O: meat with a moderate amount of vegetables, eggs, nuts, and seeds

    Non-Compliant Foods

    • Type A: meat and dairy

    • Type B: nuts and seeds

    • Type AB: no specific foods to avoid

    • Type O: dairy and grains

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

    People with blood type B, which D'Adamo calls "the nomad," should eat a highly varied diet including fruits, vegetables, grains, beans, legumes, meat, poultry, fish, eggs, and dairy, but avoid intake of nuts and seeds.

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

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

    Recommended Timing

    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.

    Recommended Products

    In addition to specific foods, Dr. D'Adamo recommends different supplements for each blood type, which are available on the website 4yourtype.com. There is a specially formulated multivitamin, multimineral, lectin blocker, and probiotic/prebiotic blend for each blood type.

    Pros and Cons

    Like all fad diets, the blood type diet has positives and negatives. Here's a closer look:

    Pros

    • Increases energy

    • Boosts immune system

    • Improves health

    Cons

    • Lack of scientific evidence to support health claims

    • Some blood type plans lack nutrient groups

    Pros

    Proponents claim that the blood type diet can help you burn fat more efficiently, increase your energy levels, stimulate your immune system, promote weight loss, and lower your risk of major health problems like heart disease and cancer. However, there is currently a lack of scientific evidence to support these claims.

    In addition, there is no research to support that the blood-type diet is an effective weight-loss strategy. The plans for types A and O restrict certain food groups, which is not considered a healthy eating plan. Plans for types B and AB are more well-rounded and with proper planning can provide all of the necessary nutrients.

    Cons

    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 a PLoS One in 2014. For the study, 1,455 participants filled out questionnaires designed to determine how frequently they'd consumed certain foods during a one-month period.

    In their analysis of the questionnaires, researchers found that following a diet similar to the diet prescribed for blood type A or blood type AB was associated with lower blood pressure and lower cholesterol levels.


    Following a diet similar to the diet prescribed for blood type O was associated with lower levels of triglycerides (high levels of this blood fat have been associated with an increased risk of cardiovascular disease), while no significant association was found for the blood type B diet.

    Since these associations occurred independently of the participants' blood types, the study's authors state that their findings do not back up the overall theory behind the blood type diet.

    In addition, a research review published in the American Journal of Clinical Nutrition in 2013 found that further research is needed to support any of the health claims associated with the blood type diet.

    For the review, scientists looked at 16 previously published reports on the blood type diet and concluded that "no evidence currently exists to validate the purported health benefits of blood type diets."

    Since the diets prescribed for blood types A and O are very restrictive, there's some concern that individuals following these diets may fail to achieve sufficient intake of many vitamins and minerals that are essential for health.

    Although proponents of the blood type diet suggest that use of dietary supplements can help dieters meet their nutritional needs, such supplements are not regarded as a reasonable substitute for a healthy, balanced meal plan.

    How It Compares

    While the blood type diet is based on a scientific theory, it isn't rooted in scientific fact and its effectiveness has not been studied.

    The overall plan recommends whole, natural, and unprocessed foods, which makes it healthier than a pre-packaged meal plan or meal-replacement plans. However, the prescribed plans for each blood type eliminates some foods that are considered crucial to good health.

    USDA Recommendations

    The U.S. Department of Agriculture (USDA) dietary guidelines provide recommendations for a healthy, balanced diet. The following nutrient-dense foods are considered part of a healthy diet:

    • Vegetables and dark, leafy greens (kale, spinach, broccoli, Swiss chard, green beans) 
    • Fruits (apples, berries, melon)
    • Grains (quinoa, brown rice, oats)
    • Lean meats (chicken breast, fish, turkey breast)
    • Beans and legumes (all beans, lentils, peas)
    • Nuts and seeds (walnuts, almonds, sunflower seeds)
    • Dairy (reduced fat milk, cheese, yogurt) 
    • Oils (olive oil, avocado oil) 

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

    The USDA recommends consuming roughly 1,500 calories per day for weight loss, but this number varies based on age, sex, weight, and activity level. Use this calculator to determine the right number of calories for you.

    Similar Diets

    The blood type diet is unique in that it tailors diet and exercise to your specific diet. The plan recommends eating whole and unprocessed foods, which is similar to these other diets:

    • Whole30: The Whole30 is a 30-day diet that eliminates sugar, alcohol, grains, dairy, and most legumes. That makes it challenging to get all the nutrients your body needs. You could also easily get too much of foods you don't need (red meat and saturated fats).
    • Plant-based diet: A plant-based diet is one that focuses on plants, such as fruits, vegetables, tubers, seeds, legumes, and grains. People on plant-based diets typically avoid beef, poultry, fish, eggs, and dairy, or eat them only in small quantities.
    • Whole-food diet: A whole-food diet focuses on eating foods that remain close to their state in nature. This diet includes all food groups, so it should meet basic nutritional needs.

    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 strategy for weight loss. If you're considering it, make sure to talk with your primary care provider first.

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