Blood type diet
The blood type diet is a nutritional approach developed by Peter J. D'Adamo, which suggests that an individual's blood type influences their dietary needs and health. The diet categorizes foods based on their compatibility with different blood types—O, A, B, and AB—arguing that consuming foods aligned with one's blood type can enhance health and prevent disease. According to D'Adamo, each blood type has distinct ancestral eating patterns and digestive responses to lectins, proteins found in plants that can affect health when incompatible. For example, type O individuals are encouraged to adopt a high-protein diet similar to hunter-gatherers, while type A individuals are advised to follow a vegetarian diet reflective of agricultural societies.
Despite its popularity since the publication of D'Adamo's book "Eat Right 4 Your Type" in 1996, the blood type diet faces significant criticism from the scientific and medical communities. Many experts argue that the diet lacks empirical support and that its claims oversimplify the complexities of human biology and dietary needs. A 2013 review in the American Journal of Clinical Nutrition concluded that there is no scientific evidence validating the diet's benefits, though some individuals may experience health improvements due to adopting healthier eating habits overall. As a result, while the blood type diet presents an intriguing approach to nutrition, it remains controversial and is not widely endorsed by health professionals.
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Blood type diet
A blood type diet is a type of diet that is based on a person's individual blood type. Peter J. D'Adamo, a naturopathic practitioner with a degree in alternative medicine, created the blood type diet. The diet touts the benefits of restricting a person's diet based on his or her blood type, with each blood type group subscribing to specific eating habits. The theory behind the diet states that each blood type digests lectins—proteins found in plants—differently. If a person eats foods containing lectins that are not compatible with his or her blood type, health issues arise. The diet also relies on a theory involving the evolution of blood types, with different blood types descending from different evolutionary periods. According to D'Adamo, eating in compatibility with blood type is supposed to make a person healthier. However, the diet is considered a fad diet, and many doctors, nutritionists, and scientists have dismissed D'Adamo's claims.
Background
The blood type diet was first introduced in 1996 with the publication of Peter J. D'Adamo's Eat Right 4 Your Type, which became a best seller. D'Adamo was part of the first class that graduated from Bastyr University, a school of alternative medicine. He described himself as a naturopathic practitioner who dabbled in research, horology, and software development. His father was famous naturopath James D'Adamo, who first championed tailoring one's diet based on blood type and applied his ideas in his practice. D'Adamo's father prescribed a low-fat, vegetarian diet to all of his patients. He noted that while some benefitted from the diet, others did not.
D'Adamo decided to conduct research based on his father's observations. He examined the various diseases common among different blood types. As D'Adamo continued his research, he formed a hypothesis that some blood types are more prone to certain health issues than others are. He then posited that a person's blood type correlated with his or her ability to process certain foods, specifically the lectins found in those foods. Lectins are a class of proteins derived from plants, chiefly seeds and grains. Lectins bind to specific carbohydrates, or sugars, and promote a process known as agglutination, or cell clumping. Lectins also play a role in the attachment of bacteria and viruses to blood cells. According to D'Adamo, cell clumping can cause a myriad of health issues if the lectin in a food is not compatible with a person's specific blood type.
The blood type diet also postulates that each blood type derives from different evolutionary periods. Type O is considered the oldest blood type found in humans and dates back to the times of hunter-gatherers. Type A supposedly developed when humans began to cultivate the land, leading to diets rich in produce, beans, legumes, and grains. Type B originated in the nomadic societies, in which people's diets often contained dairy. AB blood type is considered the newest blood type and has characteristics of both A and B blood types. D'Adamo used these factors to create four diets for each specific blood type.
Overview
D'Adamo's book recommends diets for each blood type based on the interaction of lectins with blood cells and the ancestral eating habits of the specific blood types. People with type O blood should eat a diet full of lean meat, poultry, fish, and vegetables, much like their hunter-gather ancestors. The type O diet limits grains, beans, and dairy and encourages people to avoid items such as lentils and caffeine. D'Adamo also recommends rigorous exercise for people with type O blood. People with type A blood should stick to a meat-free diet of fruits, vegetables, beans, legumes, and grains that resembles the eating habits of their agricultural forbearers. According to D'Adamo, people with type A blood have very sensitive immune systems and a higher risk of disease. He also encourages mindful practices, such as tai chi, to promote health in those with type A blood. Individuals with type B blood are encouraged to stick to a diet of green vegetables, eggs, some meats, and low-fat dairy. Type B patients should avoid foods such as chicken, corn, buckwheat, lentils, tomatoes, peanuts, and sesame seeds. Lastly, people with AB type blood have the fewest restrictions of all the diets. AB types should refrain from eating buckwheat and smoked meats. Foods such as lamb, dairy, tofu, and grains are highly beneficial to people with type AB blood.
The blood type diet has many critics. The majority of scientists and health professionals do not support the diet's conclusions, and many feel that D'Adamo's claims lack scientific merit and allow for broad generalizations about the diverse human population. In addition, no evidence exists linking blood type to evolution. Although D'Adamo's claim that certain illnesses are more likely to occur in specific blood groups is true, people's diets are not likely responsible for these incidences. Since many of the recommended diets encourage generally healthy eating habits, researchers believe any improvement in health is primarily attributed to these changes and likely has nothing to do with eating specially for one's blood type.
In 2013, the blood type diet was subjected to a major scientific review published in the American Journal of Clinical Nutrition. The review found no existing scientific evidence supporting the benefits of a blood type diet. The review found that the diet might help a person lose weight because it is highly restrictive, eliminating processed foods and simple carbohydrates, such as refined sugar, from one's diet. The review found no research supporting the claim that the diet improves digestion or increases energy, however.
Bibliography
"Blood Group Genetics, Exercise and Stress." The Blood Type Diet Official Web Site, www.dadamo.com/txt/index.pl?1002. Accessed 5 Apr. 2017.
"Blood Type and Your Health." The Blood Type Diet Official Web Site, www.dadamo.com/txt/index.pl?1001. Accessed 5 Apr. 2017.
Cusack, Leila, et al. "Blood Type Diets Lack Supporting Evidence: A Systematic Review." American Journal of Clinical Nutrition, vol. 98, no. 1, 2013, pp. 99–104.
Jingzhou Wang, et al. "ABO Genotype, 'Blood-Type' Diet and Cardiometabolic Risk Factors." PLoS ONE, vol. 9, no. 1, 2014.
Laufer-Cahana, Ayala. "Study Explores the Scientific Support for the Blood-Type Diet." The Huffington Post, 3 June 2013, www.huffingtonpost.com/ayala-laufercahana-md/blood-type-diet‗b‗3351710.html. Accessed 5 Apr. 2017.
Miller, Kelsey. "Why The Blood-Type Diet Is A Dangerous Myth." Refinery 29, 11 July 2016, www.refinery29.com/2016/07/116159/blood-type-diet-myths. Accessed 5 Apr. 2017.
"Theory behind Popular Blood-Type Diet Debunked." Science Daily, 15 Jan. 2014, www.sciencedaily.com/releases/2014/01/140115172246.htm. Accessed 5 Apr. 2017.
Watson, Stephanie. "The Blood Type Diet." WebMD, www.webmd.com/diet/a-z/blood-type-diet. Accessed 5 Apr. 2017.