By Jennifer Boyer, Staff Writer, American Association of Blood Banks
Blood products and pop culture are an unlikely combination. Yet blood products have found their way into pop culture consciousness in recent years from celebrities publicly supporting blood-related causes to the vampire and zombie crazes. They are even impacting lifestyle choices such as diet, exercise and dating.
“People have always tried to find explanations for things they don’t understand,” said Mark Yazer, MD, associate professor of pathology at the University of Pittsburgh, medical director of the RBC Serology Reference Laboratory and assistant medical director of centralized transfusion service at the Institute for Transfusion Medicine.
The Blood Type Diet
“You are what you eat” never rang truer than with the Blood Type Diet, which gained traction in the mid-1990s with the release of “Eat Right For Your Type” by Peter J. D’Adamo. This book explores how blood type is the key to your biochemical uniqueness that when you eat right for your type, your body responds the way nature intended. The diet also heavily cites anecdotes and research linking blood type with certain illnesses.
D’Adamo’s diet centers on three “legs”: lectins, polyamines and secretions.
Lectins. When someone eats food containing protein lectins that are incompatible with his or her blood type antigen, the lectins target an organ or bodily system causing blood cells in that area to clump together.
Polyamines. This leg addresses the effect of foods on each blood type regarding their interactions with intestinal bacteria and the mucous secretions of the gut.
Secretions. Leg three highlights the secretor differences regarding digestive juices among the blood types and the blood type variability in the secretion of intestinal alkaline phosphatase.
Most nutritionists and serologists argue that the Blood Type Diet is unsupported by proven scientific evidence and controlled studies. However, others admit that lack of extensive correlating data aside the diet is fairly healthy because it encourages the elimination of unhealthy and processed foods. Unfortunately, it also means that dieters will probably end up foregoing certain healthy foods as well. For example, Blood Type A thrives on a primarily vegetarian diet, or one that specifically avoids meat, dairy, kidney and lima beans and wheat.
“The reason why people did so well on the D’Adamo Blood Type Diet was because they ate healthy food, not because of the specific healthy food they were eating,” said Judy Sullivan, MS, MT(ASCP)SBB, quality source consultant at Blood Systems, Inc.
“In and of itself, I don’t see it as harmful. But the only way that you would be able to test its effectiveness would be to take a sample of Group-O people and give them a Group-A diet for six months and then follow them,” she explained.
“If it encourages people to eat in moderation, then in principle it’s not a bad thing,” said Yazer. “However, anything extreme that gets people to cut out healthy foods should be viewed cautiously.”
Relationships Between Blood and Disease
The Blood Type Diet rests heavily on the idea that there is an association between blood types and risk of certain diseases. For example, because individuals with Type-O blood are believed to be prone to peptic ulcers, they are steered away from eating acidic food and toward alkaline foods.
Indeed, the scientific literature, including reports and studies from the “British Medical Journal,” “Science” and the “European Journal of Clinical Microbiology and Infectious Diseases” have suggested that blood group antigens may act as receptors for parasites, bacteria and viruses, causing blood types to be aligned with certain health conditions.
“There have been studies that have shown that there are relationships among blood group systems and disease,” said Sullivan.
The belief that certain blood types are associated with particular ailments is not new. “While there appear to be some associations among blood groups with disease, what remains debatable is whether the many statistical associations mean anything and whether blood group antigens play a biologic role,” said George Garratty, PhD, FRCPath, scientific director at American Red Cross Blood Services Southern California Region.
“The ABO blood group is statistically not always causally linked to lots of things that you just wouldn’t expect, such as Group-A people having a higher risk of pancreatic cancer and Group-O people with reduced levels of von Willebrand, or vWF, factors,” explained Yazer. “We don’t know why these things happen, especially the link with pancreatic cancer, but there’s a statistical correlation.”
Blood Type and Fitness
If blood type determines what you should eat, believers say, then it also should determine how you work off what you eat. D’Adamo’s book, “Just an Ounce of Prevention … Is Worth a Pound of Cure,” examines the theory that each blood type has its own fitness needs. For example, Type B should choose physical exercise that is challenging to both mind and body. A combination of strenuous and meditative exercises is beneficial, including aerobic exercise, team sports, swimming, jogging, yoga, gymnastics, tennis, martial arts, cycling and golf are all good options.
“You can make the case that just as ABO is linked to levels of vWF, then maybe it also is linked to the neurotransmitters that determine proclivity toward certain types of exercise,” said Yazer. “It might be interesting to look at champion sprinters to see if they’re all the same blood group, and if it’s different than that of, say, world-class European handball players or shot putters.”
Blood Type and Personality
Much like astrological horoscopes, there is a popular belief in Japan and South Korea that a person’s ABO blood type plays a strong role in determining personality and relationship compatibility.
Japanese morning television shows and newspapers feature blood type horoscopes, while women’s magazines cover the topic to help readers gauge compatibility with potential partners.
Books on blood type analysis remain top sellers. Many job application forms include a space for blood type. Theoretically this allows
employers to assess a potential employee’s temperament. In Japan some matchmaking agencies ask clients to fill in blood type alongside height and weight.
The mindset that blood type determines personality also exists in the western world. American website DateByType.com allows users to strike a love match based on blood type. (For the record, A is said to be most compatible with A and AB; B with B and AB; AB with AB, B, A and O; and O with O and AB.)
The Blood-Personality Connection
In terms of assessing personality types, “You’re better off going with zodiacs than blood types,” said Dawn Rumsey ART(CSMLS), global support engineer, reagents, at Immucor, Inc. Just as the ancient Greeks aligned personality traits and behaviors with the four humors, Rumsey believes the blood type personality proponents are “taking standard Greek personality profiles and blending them.”
“The connections that have been made previously between diet and exercise are probably pseudoscience, but it’s not completely unthinkable that ABO is actually related to behavior and physical and personality attributes,” Yazer acknowledged. It’s a stretch but just as ABO is linked to vWF levels, maybe ABO is also linked to some neurotransmitter that controls personality and behavior. Thus perhaps one’s personality might be reflected by some currently unknown connection between their ABO group and behavior-modifying neurotransmitters.”