To begin with, what exactly is a blood type? Blood types or blood groups are defined as any of the various types of human blood whose antigen characteristics determine compatibility in transfusion. There are four main blood types. These are types A, B, AB, and O (Landsteiner 1900) and together these types are collectedly referred to as the ABO system.
You may be saying to yourself, okay that’s great and all, but what the heck is an antigen? Well an antigen is a toxin or other foreign substance that when introduced into the body elicits an immune response, especially the production of antibodies. Your red blood cells contain a special type of antigens known as self-antigens. Self-antigens (usually referred to simply as antigens) are a type of protien attached to your red blood cells and the immune system does not normally attack them. So the type of antigens you have in your system determine your blood type. For instance, people with the A antigen have blood type A while people with the B antigen have blood type B. Some people have neither antigen and this means you have blood type O. If you have both antigens your blood type is AB. Make sense so far? Good, because it’s about to get a little more confusing.
Along with these specific antigens come specific antibodies. Antibodies are a product of the immune system and they help us fight off harmful or foreign substances such as disease and infection. Whichever antigen is absent from your own system will determine the type of antibodies within your blood serum. Type A blood has antibodies to defend against type B antigens and Type B blood has antibodies that defend against type A antigens. This is why people with blood type A are unable to accept transfusions from people with blood type B, and vice versa. Their respective immune systems would view the foreign antigens as harmful and attempt to destroy them. Meanwhile Type O blood has neither antigen and it carries both types of antibodies. Although on the surface it may seem counter-intuitive, Type O is the universal donor and can be given to any blood type in the ABO family, but it is unable to accept blood other than type O. Type AB carries neither antibody so this type is the universal recipient. For more information, check out Blood Groups and Red Cell Antigens 2005 by Dr. Laura Dean.
From biochemical and anthropological testing we know that each blood type showed up at different points in human history. Type O is generally accepted as the oldest blood type (though there is some debate about this). The lifestyle of these early type O people was nomadic and they obtained food via hunting and gathering. When people migrated to other parts of the world they faced different challenges. Blood groups mutated in response to these changes. Some people settled down and started an agricultural lifestyle. These people eventually developed type A blood. Meanwhile, other people migrated to the Himalayan highlands, now part of present day Pakistan and India. Blood mutations in that region gave rise to type B blood. Its theorized that these mutations were most likely a response to climactic changes and differences in available food sources. Blood type AB came about when different tribes intermingled with one another. Until then most people lived in fairly isolated groups. Type AB blood is the least common blood type found among present day people because it has existed for a shorter period of time than the others. The key point to remember here is that one possible contributing factor to blood type mutations was available food sources. If this theory is correct, it stands to reason that eating for your blood type may indeed be a good idea.
So now let’s look at some specifics. If you skipped ahead to this part, I really suggest you go back and review the previous sections of this article. Especially the part about Potential Risks and Problems Please understand this is simply a summary of his suggestions. If your curiosity is piqued, you should really read the book.
As the majority of people have type O blood, let us begin with the optimum diet for this blood type. People with type O blood are true carnivores. They can digest meat easier than any of the other blood types. Low fat meats, such as lean beef and lamb, and fish high in omega-3 fatty acids are the best sources of protein for them. Type O people need high protein diets. Fresh vegetables and fruits are also recommended. Grains and dairy products, however, are more difficult for them to digest and cause them to get fat easily. As their ancestors were very active, high levels of exercise are recommended for type O people. Any exercise that improves the heart rate function and muscles, such as boxing, are recommended. Type O’s tend to have lower levels of thyroid hormones, often show insufficient levels of iodine, and have higher levels of stomach acid than the other blood types. It is therefore believed that type O people have higher risks of developing ulcers and thyroid disorders.
The next most common blood type is A. The recommended diet for type A people is one that is rich in carbohydrates, such as rice and grains, vegetables, and fruit. Dairy product and meat, however, are harder for them to digest. It is therefore recommended that A type people get their protein from foods such as beans, fish, or tofu. Type A people are generally the best candidates for a vegetarian diet. Type A’s have a naturally high level of cortisol, a stress hormone, which increases quickly in stressful situations. Therefore, to help relieve some of this stress, slow exercises such as yoga are recommended. Relaxation is key to the health of type A’s.
Blood type B people can digest most foods quite easily as their ancestors were exposed to various foods to survive in their extreme environment. It is important for type B people to keep their diets varied. Lean meats that are low in fat are easiest for them to digest and will often speed up their metabolism. Chicken, sesame, corn, lentils, tomatoes, and wheat, however, tend to make type B people fat. While type B people also produce elevated levels of cortisol, they are able to clear nitric oxide (a neurotransmitter) more quickly than other blood types. What this means is that although they may get stressed more easily, they are better at coping with it. Both active sports and slow exercises such as yoga are recommended. Any sport that requires both physical and mental strength, such as tennis and martial arts, are most encouraged.
People with blood type AB have features of both type A and B. Like people with type A, they do not have enough stomach acids to easily digest some kinds of meat. They are therefore also recommended to get their protein from soy beans and fish. Foods that lower the metabolism of type B people will usually have the same effect on type AB people. Type AB people often struggle with strong emotions of anger and depression. Exercise is therefore crucial for their health. Both calming activities and intense physical exercise is recommended.