- The Scientific Argument Against Blood Type Diets
- Scientific Argument Against Blood Type Diets-1 . Blood Types Evolved Before Humans Did
- Arguments Against Blood Type Diets: Bacteria & Viruses- Not Food Account For Differences In Blood Types In Different Populations
- Arguments Against Blood Type Diets: Race Has Nothing To Do With Blood Type Or The Foods You Should Eat To Stay Healthy
The Scientific Argument Against Blood Type Diets
Blood type diets have been in vogue for several years now and have generated significant incomes for many a ‘nutritionist’. It’s founder, Dr. Peter D’Adamo, proposed that blood types are directly related to how our bodies react to certain foods, and that you should eat diet specific to your blood type for optimum health and weight maintenance. There are a slew of celebrities who swear by it along with many big names in the nutrition field. As popular as it may be, the blood type diet, like so many others lack any credible foundation in scientific fact. True science is absent in most of the commercial literature promoting diets and nutrition, and one of the most frustrating aspects of living in an age of constant exposure to health and fitness related information is that it has become difficult for the average person to differentiate between scientific facts and product promotion. We turn to sources of dietary and health information when we have a problem- be it a struggle with weight loss, allergies or some other health concerns and we want to believe that there is a simple explanation for our problems and also a simple solution. Belief based diets offer much in the way of hope but little in the way of peer reviewed and credible scientific explanation-using popularity to circumvent science based evidence. They also prey on our innate desire to have our problems solved in a convenient manner, but as far as blood type diets are concerned, an understanding of the evolution of blood type variations gives us insight into the shortcomings of any blood type based diets or diagnoses.
The premise of the blood type diet is that blood types somehow evolved as we did as a species. The theory, put forward by Dr. D’Adamo and its proponents is that the universal blood Type O was first to evolve due to our hunter-gatherer lifestyle. As such, individuals with this blood type should gravitate towards eating a high protein, ‘Paleolithic type’ diet. As time went on, (around 15,000’s BC), Blood Type A came into being, as man switched from being a hunter gatherer to a more agricultural lifestyle. As such people with Type A blood should eat a primarily vegetarian diet. Blood Type B supposedly came into existence at 10,000 BC, when according to the theory, some groups of humans suddenly became nomadic and were eating a diet of grains. Finally, within the past thousand years, Type AB surfaced from people who ate a wide variety of food. According to blood type diet advocates, there is research showing that a specific set of proteins called lectins interact with the different ABO blood types. The theory goes on to say that this research has found that these lectins can be incompatible and even harmful with some blood types so people with different blood types should eat different foods.
Scientific Argument Against Blood Type Diets-1 . Blood Types Evolved Before Humans Did
All of this sounds pretty convincing and scientific and it has helped sell millions of copies of Dr. D’Adamo’s books on the subject, but the theories sound pretty outlandish to anyone with an understanding of polymorphism- (the different ABO Blood Types). It is an accepted fact that polymorphism- which was first categorized by Nobel Proze Winner, Karl Landsteiner in 1900, occurred millions of years ago, not thousands of years ago. This isn’t an esoteric piece of information as the diversity of blood types has always been a cornerstone of scientific research into our ancestral origins and is the basis of Immunohematology. Without our understanding of these concepts, blood transfusions would not exist and advances in molecular characterizations of blood type diversities confirm these findings. One of the problems with science is that many find the terminology intimidating as scientists write primarily for other scientists and not the average man or woman on the street, but I can assure you that it is not as complicated as it seems, and taking the time to keep abreast with findings in science make it really hard for you to fall for the pseudoscience and conjecture found in so many pieces of diet related advertising. That being said, here is a breakdown of how blood types evolved:
The type of blood a person has is determined by alleles at a single locus at chromosome 9. These alleles encode for different amino acids called glycotransferases.
In blood type A, cytosine at nucleotide site 793 translates to leucine 265 and guanine at nucleotide site 800 translates to glycine 267.
In order blood type B, the cytosine at 793 translates to methionone 265 and the guanine at 800 to alanine 267.
Blood type AB occurs when both changes occur.
Blood type O is caused when an inactive or nonfunctional protein is coded.
Studies have shown that polymorphism exists in all anthropoid primates. Given the similarities between human blood and that of several primates, scientists are able to use what they know based on the average mutation rate that must have occurred for there to be a divergence of A and B blood types. Using those estimates, some scientists concludedthat A and B types diverged at least 13 million years ago, , completely contradicting the blood type diet conjecture about blood type diversity being fairly recent, as polymorphism seems to have occurred at least eight million years before the first ape-like man even began walking on two legs. Other studies estimate that the blood groups would have diverged 4.5 to 6 million years ago, but in spite of the differences in estimation all accounts point to polymorphism being an occurrence that predates modern man.
There is evidence as well that Blood Types A and B may have been the original blood types and not Type O as the blood type diet theory claims. Type O seems to represent an abnormal mutation as a result of a defective gene as normal genes such as A and B cannot evolve from abnormal ones.[4,5,6,7,8, 9, 10, 11] Although the O blood type is common in all populations around the world , there is no evidence that the O gene represents the ancestral gene at the ABO locus. Nor is it reasonable to suppose that a defective gene would arise spontaneously and then evolve into normal genes.
Arguments Against Blood Type Diets: Bacteria & Viruses- Not Food Account For Differences In Blood Types In Different Populations
The change in eating habits from primarily vegetarian primate to the carnivorous hunter-gatherer diet occurred millions of years after blood types diverged and thus pressures from food changes cannot be taken into account as a reason for differences in blood type. The nutritional needs of today’s humans arose through millions of years of evolution during which genetic changes were a reflection of the environment and circumstances of our ancestors. That being said, since the advent to of agriculture some 10,000 years ago we have not changed much as genetic adaptation has not been able to keep up with our cultural and technological progress.[18,19] Thus the pressures of natural selection have produced at most minor alterations since the beginning of the Neolithic period and we remain almost identical to our late Paleolithic ancestors. No variations in blood type or any other such changes have occurred.
The argument against blood type based diets might have ended there, but there are even more science based reasons why such a theory doesn’t hold water. The other important chink in the armor of the blood type diet theory is the idea that specific foods are responsible for our blood type variations when diversity of blood types among specific populations can be traced to a very specific evolutionary defense against bacteria and viruses. People have either blood group A, B, AB, or O, with each type occurring at different frequencies in populations around the world. Robert Seymour and his colleagues at University College in London used mathematical models to show that this diversity is caused by natural selection pressures imposed on human populations by viral and bacterial infections and not from the foods they eat. Their model reveals that if viral infections dominate a population, blood type O will be most common, whereas if bacterial infections are more common, then A and B blood types will be more frequent. Food differences have nothing to do with it.
Arguments Against Blood Type Diets: Race Has Nothing To Do With Blood Type Or The Foods You Should Eat To Stay Healthy
The idea of race having some role in blood type diversity or the foods we should eat is another idea that is not supported by studies of human biology. Race in and of itself is not a biological reality and from a scientific point of view it is an irrelevant tern when used to describe human beings as it is a cultural or ethnic difference whereas the word race is used to denote a biological subspecies or variety of a species, consisting of a more or less distinct population with anatomical traits that distinguish it clearly from other races. This biological definition does not line up with human genetic variation as humans are extremely homogenous. In fact, as much as we might like the idea of being different, we are all 99.9% genetically identical, with most of our differences stemming from gender and superficial individual personality traits. Such homogeneity is not commonplace among other animals, even among some of our closest biological relatives; chimpanzees have 2-3 times more genetic variation than humans, while orangutans have 8-10 times more variations.
Fact: Avoiding Modern Refined Foods, Eating Moderately & Exercising Help Everyone Get Into Better Shape- Regardless of Blood Type
In twenty years of working with people from all over the world I have found that there are very few differences in the dietary practices required to help someone lose weight or get into great shape. Differences abound in terms of preferences, which is completely cultural influences and occasionally due to certain allergies. True some populations can tolerate certain foods better than others, but at the end of the day anyone following a diet comprised of only naturally occurring foods in amounts proportional to their activity level can lose weight and get into fantastic shape if they eat and exercise consistently. There is no gimmickry, nor any instant solutions with diets that try to make things more complicated than nature intended, as change takes time, but for that to happen, we have to have faith. Not in blood type diets, Dr.D’Adamo’s or Dr. Atkins, instead we have to learn to have faith in science and in ourselves.
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