What Is the Rationale Behind the Lack of Evidence for Blood Type Diet?
The blood type diet is based on the theory that an individual blood type would determine the foods one should consume daily and the exercise one should do in combination with such a diet to achieve optimal systemic health results. The diet plan was originally developed as a concept by Peter D'Adamo, a naturopathic physician. The main idea or rationale is that the diet does not promote foods incorporating the consumption of lectins (a specific type of protein) or avoids foods with lectins incompatible with a person's blood type. If the lectins are incompatible with the blood group of a person, it could cause blood cell clumping or agglutination, further resulting in chronic health conditions, such as cardiovascular disease, kidney disease, or certain cancers. This theory, however, completely lacks scientific evidence according to most nutrition experts and as per the current research. Therefore, this diet is advocated by only a few people who may support these claims of purported health benefits by following such a diet plan.
Formulating a diet on blood type is not evidence-based according to medical research and the major drawback is when an individual restricts the intake of certain healthy foods and does not comprise a balanced diet form, thus predisposing an individual to systemic disease. Nutrition experts do not support or recommend this diet for achieving the nutrition or weight loss goals either.
What Is the Nature and Classification of Diet Based on Blood Groups?
The blood type diet emphasizes certain foods and exercise plans for individuals based on their varying blood group types. Regardless of the blood type, however, the diet focuses on consuming whole foods while minimizing the consumption of processed foods in general. The pattern, nature, and claims of the blood type diet are as follows:
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People With Type A Blood: These individuals might be possibly predisposed to heart disease, cancer, and diabetes and hence may opt for an organic, vegetarian diet paired with calming, centering exercise regimens like yoga and tai chi. People with blood type A according to D'Adamo are called "cultivators". These individuals should follow a dairy-free, vegetarian diet that includes fruits, vegetables, grains, beans, legumes, nuts and seeds.
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People With Type B Blood: According to D’Adamo, these individuals possess a more robust immune system and a tolerant digestive system with more adaptability compared to other blood types. Also, these people are more susceptible to autoimmune disorders like chronic fatigue, lupus, and multiple sclerosis. People in this group should hence consume a highly varied diet that comprises fruits, vegetables, grains, beans, legumes, meat, poultry, fish, eggs, and dairy. These individuals should strictly avoid nuts and seeds according to this diet.
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People With Type AB Blood: These individuals have a biologically complex blood type and are called "enigmas" by D'Adamo. Though these individuals have absolutely no restrictions and can consume any food recommended for both blood Type A and B, aiming for a vegan diet is advised for this type.
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People With Type O Blood: Based on this theory, individuals with Type O blood should exercise more or include intense physical activity or workouts. They can consume animal proteins but not dairy products or grains, which can predispose them to systemic problems. According to D'Adamo, people with blood type O are referred to as "hunters," meaning it is ideal for the blood type to stick to a dairy-free and grain-free diet that is high in meat and includes a moderate amount of vegetables, eggs, nuts, and seeds.
Why Is Blood Type Diet Restrictive?
Although each blood type would have its dietary restrictions, this diet plan is not a low-calorie diet with unhealthy restrictions, especially based on calorie intake like other fad trends. It also advocates healthy all-round exercise and variations based on each blood type. The point to further note is that the diet plans for Type B and AB are more well-to-do and can provide most of the necessary nutrients needed for a well-balanced diet. However, the plans for Type A and O are certainly more restrictive, and even amongst certain healthy food groups, this plan may not be applicable for long-term eating plans because of the cutbacks on major food products. Currently, according to both medical and nutrition research, there is no specific evidence to support the claims, rationale, or benefits that could accompany following the blood-type diet as such.
At best, it would be deemed a weight-loss strategy because it promotes exercise regimens regularly amongst varied blood group types.
Why Do Nutrition Experts Not Support This Diet?
A major portion of professional health care providers and nutrition experts tend to concur globally on the nature of diet an individual needs to follow which should ideally be ‘balanced’ meaning that the diet that is satiating, unrestrictive, and sustains healthy weight, prevents obesity and supplies the body with the much needed immune boost and nutrients needed for daily activity, energy, and metabolism. The blood type diet hence is in complete contrast to this definition of a balanced diet by healthcare professionals throughout the globe. Though individual opinions amongst health experts may vary, any diet that is not rooted in science or has no scientific evidence to back its claims cannot be considered safe in the long run for improving the systemic health status.
What Are the Evidence-Based Studies Citing No Benefits of Blood Type Diet?
According to a major evidence-based research review published in 2013, no evidence exists to support any of the health claims that are associated with the blood type diet. In this review, scientists observed 16 previously published reports on the blood type diet to reach this conclusion as well.
A recently published primary research-based review in 2020 observed that there would be no cardiometabolic benefits to be gained from following the blood-type diet.
Conclusion
Nutrition experts always recommend that one should follow an unrestrictive, balanced, and satiating diet plan. The diet must be best suited to the body type and should comprise nutrient-rich foods for systemic health, which includes whole foods, grains, legumes, pulses, fruits, vegetables, poultry, dairy products, and protein-rich foods. Even more importantly, following a health regimen that combines a sensible form of calorie restriction with regular exercising is deemed the most effective strategy to sustain a healthy weight and keep the nutrition status in check
