Lectins

Related Terms

Blood type A, blood type AB, blood type B, blood type O, blood typing, BTD, diet, Eat Right 4 Your Type, ER4YT, lectins, Peter D'Adamo, Rhesus factor.

Background

The blood type diet is a diet prescribed by Peter D'Adamo, which is described in his book, Eat Right 4 Your Type. Other supporters of the diet include various medical professionals, such as Ann Louise Gittleman, M.S., C.N.S., Christiane Northrup, M.D and Bruce West, M.D. D'Adamo asserts that a person's blood type is the most important factor in determining a healthy, individualized diet. D'Adamo draws evidence from the research of immunochemist and anthropologist William C. Boyd, who surveyed the distribution of blood types globally, as described in his book Genetics and the races of man: An introduction to modern physical anthropology.
Peter D'Adamo proposes that certain lectins, or proteins which specifically bind or crosslink carbohydrates on cell surfaces, can cause blood clots in an individual with a certain blood type. These blood clots may result in serious liver or kidney diseases or dysfunctions. D'Adamo uses this principle to recommend which foods should be included or excluded from a person's diet, based on their blood type.
He also believes that elevated urine indican levels, which are apparent in a multitude of gastrointestinal diseases, can be attributed to specific blood types affecting the interactions of foods with intestinal bacteria. The level of indican is a measure of the efficiency of protein digestion. The indican scale measures the presence of indol, a metabolic byproduct of the action of intestinal bacteria on the amino acid tryptophan. Insufficient gastric hydrochloric acid, insufficient digestive enzymes, adverse food reactions, parasitic infection, fungal infection, overgrowth of bacteria that metabolize specific proteins, hypermotility of the small intestine, or other gastrointestinal dysfunction can compromise protein digestion. Poor protein digestion also can result from the dietary intake of protein from a group of food proteins called lectins.
According to D'Adamo, varying blood types affect the body's secretion of digestive juices. For example, blood Type O is capable of producing a high level of stomach acid, which could result in a greater incidence of gastric ulcers. This is an example of how certain blood types may be correlated with an increased risk of certain diseases.
The first step in the blood type diet is to determine one's ABO blood type. This can be done by having a donor card from the Red Cross, having been blood typed by a hospital prior to a medical procedure, asking a doctor to determine one's blood type, or purchasing a home blood typing kit. Relying on the recollection of a relative is not recommended to avoid mistakes. The diet is structured around a person's ABO type, rather than the Rhesus (Rh positive or negative) type.
After determining one's blood type, a person can than consult a list of food compatible with his or her blood type. Lists are also available for foods that should be avoided with a certain blood type.
According to D'Adamo, blood type influences digestion, and this is why different blood types have different strengths and weaknesses. Lectins in the diet often establish which foods are beneficial or harmful for a particular blood type. The blood type diet classifies certain foods as ' neutral, or 'avoid,' or 'beneficial' based on a person's blood type.

Theory / Evidence

The theory behind the blood type diet is the belief that lectins, proteins found in foods, can cause damage to the body. It is thought that certain lectins are compatible with certain blood types. Therefore, if a person eats a food containg lectins that is not compatible with his or her blood type, the consumption of this food can lead to medical problems such as kidney disease or cancer. This diet proposes that by focusing on foods that coordinate with your blood type, you can avoid the negative effects of certain lectins.
D'Adamo also theorizes that a person's blood type affects their ability to digest various foods. For example, he claims that Type O's are capable of digesting meat effectively due to high levels of stomach acid assosiated with their particular blood type. Type A's, in contrast, have low stomach acid and store meat as fat rather than digesting it.
D'Adamo bases his theories on research he has conducted since the 1990s, studying the connections between blood type, food, and disease. This research has built upon that of his father, a naturopathic physician. Based on his father's observations of his patients, D'Adamo also recommends different levels of exercise based on blood type, suggesting that type O's should exercise vigorously, B's moderately, and A's gently. According to D'Adamo, AB's need calming exercises.
D'Adamo classifies blood group O as "the hunter" and the earliest human blood group, thought to be muscular and active. He suggests that type O's include an abundance of meat in their diet, and a low amount of carbohydrates. He suggests enriching this diet with fruits and vegetables, limiting wheat germ, whole wheat and corn, and avoiding dairy products and most nuts. He states that Type O's are commonly afflictes by hypothyroidism, high stomach acid, and thin blood.
In this diet, group A is called the "cultivator".or this blood type, D'Adamo emphasizes a more vegetatian diet, omitting red meat. He recommends a high carbohydrate, low fat diet, consisting of a lot of fruits and vegetables. D'Adamo states that type A's have thicker blood and a sensitive immune system, and should avoid dairy and animal products. They have a higher risk of cardiovascular disease, diabetes, and cancer.
Type B is classified as the "nomad", having a strong immune system and a good digestive system. According to the blood type diet type B is the only blood type that can thrive on dairy products. They should consume a balanced diest of fruits, vegetables, dairy, and meat, but should avoid chicken. This blood type is the most likely to overcome most diseases.
According to D'Adamo group AB is the "enigma", having a blood type diet in between types A and B. These individuals should consume a mostly vegetarian diet with occasional meat, fish, and dairy, but should avoid chicken.
Blood type may be a way to identify the individual diets that will aid in healing the body. This diet is considered by some as giving physicians the ability to 'treat the patient, not the disease."
Evidence: Although commonly used for weight loss or disease prevention, there is a lack of available scientific evidence demonstraitng the efficacy of the blood type diet for these uses.

Author information

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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Boyd, W.C. Genetics and the Races of Man. Boston: Little Brown & Co., 1950.
D'Adamo PJ, Kelly GS. Metabolic and immunologic consequences of ABH secretor and Lewis subtype status. Altern Med Rev. 2001 Aug;6(4):390-405.
D'Adamo, P.J. Eat Right 4 Your Type. USA: Penguin Group, 1996.
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