Eat Right 4 Your Type

by

Courtney Sanders

 

 

Eat Right 4 Your Type, by Dr. Peter J. D’Adamo, was one of many diet books that hit the bookstores in 1996. This diet program uses the four blood types as a premise for what foods one should eat, what type of exercise one should do, and to what diseases one is susceptible. After careful review of the scientific literature, I was unable to find any studies that evaluated the validity of the book’s claims. There are numerous scientific studies that examine the roles of certain foods on health and diet, and there are plenty of studies that focus on the correlation between blood type and disease. However, there seem to be no studies devoted to the entire D’Adamo program itself.

Dr. Peter D’Adamo and his father, Dr. James D’Adamo, worked in the field of blood type analysis. His father noticed that many patients from European Spas who were on strict vegetarian diets or low-fat diets did not lose weight. Some patients actually worsened. Dr. James D’Adamo eventually suspected that blood type might be the cause. Since blood is the fundamental source of nourishment to the body, perhaps some aspect of the blood could help identify the differing results. The study was successful in that blood type was correlated with the patients’ successes or failures on specific diets. Type A did poorly on high-protein diets, but did very well on vegetable proteins such as tofu and soy. Type A benefited from lighter forms of exercise, such as yoga. On the other hand, Type O did well on high-protein diets and benefited from intense physical activity. This led Dr. Peter D’Adamo to expand upon his father’s findings. The result was Eat Right 4 Your Type: The Individualized Diet Solution to Staying Healthy, Living Longer, and Achieving Your Ideal Weight (D’Adamo XIV).

Eat Right 4 Your Type begins by explaining why blood type is important to a person’s diet. The human body has unique chemical markers called antigens that can identify foreign substances that enter the body. One of the most powerful antigens in the body is the one that determines blood type. The different blood type antigens are so sensitive that they are the immune system’s best defense. A person’s blood type is named for the blood type antigen that he/she possesses on the red blood cells (D’Adamo 18).

If You Are…

You Have This Antigen(s) On Your Cells

Blood Type A

A

Blood Type B

B

Blood Type AB

A and B

Blood Type O

No Antigens

Blood type O contains fucose, the basic sugar of all of the blood types. Each of the blood types is fructose (type O) plus another sugar. This is why type O is the universal donor, and also why type O cannot accept another blood type. Type A is fucose plus N-acetyl-galactosamine. Type B is fucose plus D-galactosamine. Type AB is a combination of fucose and the sugars from Type A and Type B (D’Adamo 19).

Because the blood types are made up specific sugars, they have antibodies to foreign sugars. This is where diet comes into play. A chemical reaction occurs between the blood and the foods consumed. This is due to a factor called lectins. Lectins are abundant and diverse proteins found in the foods we eat. These lectins have agglutinating properties that affect the blood. The basis of the blood type diet is that when you eat foods containing protein lectins that are incompatible with your blood type antigen, the lectins will target an organ or bodily system and begin to agglutinate cells in that area. For example, milk has B-like qualities. So, if a person with Type A blood drinks milk, his/her system will immediately begin the agglutination process in order to reject it. Lectins that are incompatible with the person’s blood type act as a glue, drawing in all cells in the region. These cells work actively to destroy the protein, but the results of this agglutination can include irritable bowel syndrome, cirrhosis of the liver, kidney problems, digestive problems, a slowing of the rate of food metabolism, etc. (D’Adamo 23).

Although normal cooking destroys many lectins, others are not. Gibbons and Dankers noted that in over 100 food plants containing active lectins, seven were resistant to heat: apple, carrot, wheat bran, canned corn, pumpkin seeds, banana, and wheat flour. These foods are included in many of the "avoid" categories of Eat Right For Your Type (described below). Nachbar and Oppenheim also noted high levels of lectin activity in dry roasted peanuts, Corn Flakes, Rice Krispies, and Kellogg’s Special K. They also found that the banana agglutinin was actually enhanced by heating. Another concern regarding lectins is their role in food allergies. Dietary Lectins can stimulate mast cells that can degranulate and release stored histamine (http://www.dadamo.com/literature/lrc.htm).

D’Adamo’s blood type diet is centered on these and other effects of lectins in the diet. The blood type diet acts as the restoration of your natural genetic rhythm. Within each of the food groups, there are three categories of foods: those that are beneficial, those that are neutral, and those that should be completely avoided. There are also specific exercise programs for each of the blood types. By following the guidelines, one will be able to maintain an ideal weight and improve his/her overall health (D’Adamo 34).

Being the oldest of the blood types, the digestive tracts of the Type O’s retain the memory of ancient times. The high-protein and low-carbohydrate diet in combination with intense physical activity mirrors the hunter-gatherer lifestyle of ancient man. Milks and grains are not handled as well by the Type O’s since these foods did not become part of the human diet until much later. You will lose weight on the Type O diet by restricting the consumption of grains, breads, legumes, and beans. The leading factor of weight gain in Type O’s is the gluten found in wheat germ and whole wheat products. The gluten inhibits insulin metabolism, thus interfering with efficient caloric use. Some beans and legumes also cause Type O’s to gain weight. They contain lectins that deposit in the muscle tissues, making them less charged for physical activity. Since Type O’s benefit from intense physical exercise, the deposition of lectins in muscle tissue is problematic (D’Adamo 52-53).

Blood Type A was next in the evolution of the four blood types. Type A’s flourish on vegetarian diets – the inheritance of their more settled and less warlike ancestors. Type A’s can lose weight rapidly by eliminating meat from their diets. While animal foods speed up the Type O metabolism, they slow down the Type A metabolism. Meat products become stored as fat. This is mostly due to the fact that Type A’s have low stomach-acid content and cannot digest meat as readily as their Type O counterparts. Type A’s should stay away from meats and dairy and carefully monitor their intake of wheat germ and whole-wheat products. Some wheat is fine, but too much makes the muscle tissue overly acidic. Type A’s also benefit from more relaxed forms of exercise, such as stretching and yoga (D’Adamo 97-98).

Blood Type B was third to evolve. It is the most balanced of the blood types and has the most flexible dietary choices. It seems to be an evolutionary attempt to join blood types O and A – polar opposites. The biggest sources of weight gain for Type B’s are corn, buckwheat, lentils, peanuts, and sesame seeds. Each of these foods has a different lectin, but all affect the efficiency of the Type B metabolic process. The result is fatigue, fluid retention, and hypoglycemia – a sever drop in blood sugar after eating a meal. Type B’s are similar to Type O’s in their aversive reaction to wheat germ and whole-wheat products. Type B is the only blood type in which the consumption of dairy is encouraged (it aids in Type B metabolic processes). Type B benefits from moderate exercise, such as brisk walking or light jogging (D’Adamo 145-146).

Blood Type AB is the youngest of the four blood types. In fact, it is less than a thousand years old. It is also very rare (2%-5% of the population) and biologically complex. It contains both A and B antigens. This can be positive in that the AB blood type exhibits chameleon-like responses to changing environmental and dietary conditions. For example, Type AB is the only blood type for which wheat germ and whole-wheat products are not problematic. However, the negative aspect is that Type AB is susceptible to the diseases to which both Type A and Type B are prone. Type AB should stay away from foods deemed "Avoid" for either Type A or Type B. One exception to this general rule is tomatoes. Types A and B cannot tolerate tomato lectins, but Type AB can! When it comes to gaining weight, type AB reflects the limitations of both Type A and Type B. It has the Type A low stomach acid, but it also has the Type B's adaptation to meats. Although Type AB is genetically designed to eat meats, it does not have enough stomach acid to digest meats properly. Thus, the meat gets stored as fat. Thus, for weight loss, Type AB should have smaller portions of meat and should stay away from corn, buckwheat, and sesame seeds. Type AB also benefits from moderate isotonic exercises such as hiking, swimming, bicycling, and yoga (D’Adamo 187-188).

I have found no scientific studies as of yet that evaluate the claims proposed by Dr. D'Adamo's four blood type diet. Instead of focusing on blood type and food, most studies have focused on the food and its impact on anyone's health. For example, a study on rapidly available glucose in foods was published in the 1999 edition of the American Journal of Clinical Nutrition. Its focus was the rate of carbohydrate digestion and absorption depending on the amount of carbohydrate eaten and the type of carbohydrate eaten. Carbohydrates were broken down into several categories: sugars, starch fractions, and nonstarch polysaccharides. They were then grouped as rapidly available glucose (RAG) or slowly available glucose (SAG). In this study, eight healthy adult subjects consumed eight different meals ranging in RAG from 11g to 49g. Foods with higher RAG values are more easily digested than those of lower RAG values. In foods with low RAG values, such as legumes, minimally processed cereal grains, and others, nutrients are encapsulated within cell walls (dietary fiber). This retards the release, digestion, and absorption of starches and sugars in these foods. This held true for all eight subjects. The conclusion that can be drawn from this study is that certain carbohydrates are detrimental to all people depending on the level of rapidly available glucose and the amount that in consumed (Englyst, et al. 1999). Unless all of the subjects in the study were of the same blood type (not mentioned), I believe that the results weaken D'Adamo's claims about the relationship between blood type and carbohydrate consumption.

Another study published in the 1999 edition of the American Journal of Clinical Nutrition argues somewhat against D'Adamo's claims about the negative effects of peanuts on some blood types. For instance, D'Adamo states that Type B should avoid most all nuts, especially peanuts. The consumption of peanuts by Type B would result in the agglutination process and interfere with the homeostasis of bodily systems. The study mentioned above was on the effects of peanuts as part of a heart-healthy diet. Nuts are low in saturated fatty acids and high in monounsaturated and polyunsaturated fatty acids. Evidence also suggests that they contain other bioactive molecules that have a cardio protective effect. These bioactive components include plant protein, dietary fiber, and micronutrients such as copper and magnesium. Results showed that when subjects consumed test diets including nuts, there was a 25% greater cholesterol-lowering response than was predicted (Kris-Etherton 1999). This study demonstrated the benefits of nuts to heart health. The question that remains is whether or not this cardiovascular benefit outweighs the proposed inhibited metabolism for Type B's who consume nuts.

D’Adamo also puts forth limitations on the types and amounts of vegetables each blood type should consume. However, epidemiological data support the association between high intake of vegetables and fruits and low risk of chronic disease, regardless of blood type. In a study on the health effects of vegetables and fruits in the 1999 edition of the American Journal of Clinical Nutrition, it was found that generous amounts of both resulted in a stimulation of the immune system, reduction of platelet aggregation, modulation of cholesterol synthesis and hormone metabolism, reduction of blood pressure, and antioxidant, antibacterial, and antiviral effects. Design methodologies included multiple-arm trials, randomized crossover studies, nonrandomized crossovers, and pre- and post-treatment analyses (Lampe 1999).

Some results of the study agree with D’Adamo’s conclusions, while other do not. For example, both D’Adamo and Lampe advocate diets rich in garlic (inhibits aggregation of platelets) and cranberries (antibacterial). A point of difference regards diets high in carotenoid-rich vegetables, such as carrots, spinach, and tofu and cruciferous vegetables, such as broccoli and cauliflower. According to Lampe, both of these types of vegetables are neutral if not beneficial to one’s overall health (Lampe 1999). D’Adamo, however, disagrees. Type B’s are supposed to avoid all soy products, including tofu. According to Eat Right 4 Your Type, soy and tofu contain anti-B lectins and are damaging to those with Type B blood (D’Adamo 161). Additionally, D’Adamo states that Type O’s are supposed to avoid cauliflower. Just as soy products contain anti-B lectins, cauliflower contains anti-O lectins. Thus, those with Type O blood would be harmed by consuming foods such as cauliflower (D’Adamo 68).

The final study I will draw upon from the 1999 edition of the American Journal of Clinical Nutrition concerned cereals, legumes, and chronic risk reduction. The study found that diets low in meats and high in cereals and legumes are beneficial for health. There is substantial evidence that dietary fibers, especially soluble fibers, decrease blood cholesterol concentrations. This decrease in cholesterol modifies the risk of coronary artery disease and large bowel cancers. In a study of Seventh Day Adventists, consumption of whole-wheat bread was associated with significantly reduced risk of nonfatal coronary artery disease compared with the consumption of white bread (Kushi, et al. 1999). According to D’Adamo, the consumption of whole-wheat products is detrimental to the health of blood types A, B, and O. Only Type AB is not harmed by the consumption of whole-wheat. This raises the question of benefit vs. detriment. If a food product benefits the body in one study and harms the body in another study, can any claims really be made?

The only aspect of Eat Right 4 Your Type that seems to be supported by any of the scientific literature is the discussion of the relationship between blood type and disease. However, D’Adamo takes it one step further. He not only correlates increased risk of some diseases with blood type like many of the studies, but also relates his findings back to the validity of his diet program. It is as if he were saying, "If those Type B’s had followed my plan and hadn’t eaten corn, they probably wouldn’t have gotten XYZ disease." Below is a list of the diseases to which each blood type is most susceptible (D’Adamo 333).

 

Type O

Type A

Type B

Type AB

Blood clotting disorders

Heart disease

Type I diabetes

Heart disease

Inflammatory diseases

Cancer

Chronic Fatigue Syndrome

Cancer

Low thyroid production

Anemia

Autoimmune disorders

Anemia

Ulcers

Liver and gallbladder disorders

Lou Gehrig’s Disease

Bronchial infections

Allergies

Type I diabetes

Multiple Sclerosis

Parasitic infections

 

There have been many studies that correlate Type A with higher incidences of gastric carcinoma, hypercholesterolimia and ischemic heart disease (Havlik, 1969), Type O with peptic ulcers and hyperthyroidism (Villalobos 1990), Type B with anemia, and Type AB with heart disease and bronchial infections, especially in childhood (Muschel 1966). These correlations have been documented by scientific research since the early part of the 20th century. D’Adamo is the first to offer dietary explanations for such findings.

In fact, D’Adamo is the first to offer many of the claims put forth in Eat Right 4 Your Type. There are no other diet programs like it, nor are there any scientific studies to lend support to his hypotheses. Even D’Adamo offers no examples of studies he has conducted. He talks considerably about his many years of research, but never gives tangible evidence of his findings or his patients’ experiences with the diet. Another point of concern is his lack of ethnicity as a variable. He sets limits as to the portions of foods that different ethnicities can consume each week, but he never says that his findings hold cross-culturally. I find it extremely hard to believe that the differences in cultural environments around the world simply do not matter. In fact, I find much of Dr. D’Adamo’s Eat Right 4 Your Type misleading and unfounded, as should anyone who critically examines his work. Until further research is done regarding the relationship between blood type and diet, I feel that the mass publication of this diet program is unethical and potentially detrimental to its many followers.

 

 

 

Bibliography

 

 

 

http://www.dadamo.com/literature/lrc.htm

 

D’Adamo, Peter J. Eat Right 4 Your Type. G.P. Putnam’s Sons. New York: 1996.

 

Englyst, Klaus N. "Rapidly Available Glucose In Foods." American Journal of Clinical Nutrition. 1999; 69: 448-454.

 

Havlik, Richard J. et al. "Blood Groups and Coronary Heart Disease." The Lancet. Aug. 2, 1969; 269-270.

 

Kris-Etherton, et al. "Nuts and Their Bioactive Constituents." American Journal of Clinical Nutrition. 1999; 70(suppl): 504S-511S.

 

Kushi, Lawrence, et al. "Cereals, Legumes, and Chronic Disease Risk Reduction." American Journal of Clinical Nutrition. 1999; 70(suppl): 451S-458S.

 

Lampe, Johanna W. "Health Effects of Vegetables and Fruit." American Journal of Clinical Nutrition. 1999; 70(suppl): 475S-490S.

 

Muschel, Louis M. "Blood Groups, Disease, and Selection." Bacteriological Reviews. June, 1966: 427-439.

 

Villalobos, J.J. "A 10-year Prolective Study on Cancer of the Digestive System." Rev Gastroenterol Mex. Jan-Mar 1990; 55(1): 17-24.

 

 

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