As per the author of book ?Eat Right for Your Type? Dr. Peter D'damo, there is a relationship between the blood and the foods one eats. According to him, there occurs a chemical reaction between food and blood which is caused by a factor called lectins. These lectins are a class of plant glycoproteins that act like specific antibodies but are not antibodies in that they are not evoked by an antigenic stimulus. They are abundant and diverse proteins found in foods, and have agglutinating properties that can cause various molecules and some cells to stick together.

The idea behind this theory is that blood type O's are the dominant, hunter-caveman type that require meat in the diet, that type A's are docile vegetarians, while Type B's are dairy-eating omnivores. This idea has become a manifesto for many people to rationalize including regular portions of meat and other animal products in their diet. Fortunately, most lectins found in the diet are not quite so life threatening. Ninety-five percent of the lectins one absorbs from typical diets are sloughed off by the body but at least five percent of the lectins one eats are filtered into the bloodstream and reacts differently in different organs, D'Adamos believes.What makes the "blood type" theory a little less convincing is D'Adamo's postulation that lectin proteins on some foods cause blood agglutination in people of certain blood types who are "not evolutionarily suited" to eat those foods.

However, agglutination is a very serious and potentially life-threatening phenomenon, whereby the red cells in the bloodstream stick together, and forming irreversible clumps. As we all know, red blood cells deliver oxygen to the cells of vital tissues like the brain, heart and kidneys. To accomplish this delivery, red blood cells must flow through capillaries so narrow that they must line up in a single file. If the red cells are being agglutinated by lectins or anything else, clumps of red cells will clog up the capillaries and block the blood flow. Thus, the blood stream will be prevented from delivering its life-sustaining cargo of oxygen to the tissues served by those capillaries.

Since most people are not even aware of their blood types, let alone what foods are "evolutionarily inappropriate" for them to eat, it can be assumed that on most days most people eat the "wrong foods" for their blood type. By the way there are a lot of easy ways to learn your blood type. So, according to D'Adamo's theory, many people experience repeated showers of agglutinated red cells throughout their bloodstream after almost every meal - day after day! If this is true, then blokes like me, who don't even know their blood type, are living a medical miracle everyday because if the capillary beds in our organs are subjected to barrage after barrage of agglutinated red cells, they would eventually have clogged up by now, resulting in serious tissue damage with fatal irreparable damage but thanks goodness, we are perfectly alright!

Nevertheless, we all have different nutritional needs, and different people are suited to different types and amounts of food. However, these differences are not significantly determined by the blood type, contrary to what Blood type diet theory says. There has not been any research or scientific evidence in ?Eat Right for Your Type? which proves otherwise. The only suggestion for optimal nutrition is to pay attention to what your body tells you, and to focus your diet on fresh, whole foods ? grown as organically as possible.