This is an excerpt from a recent article Dr. D'Adamo (Eat Right 4 Your Type), Posted

A chemical reaction occurs between your blood and the foods you eat. This reaction is part of your genetic inheritance. It is amazing but true that today, in the twenty first century, your immune and digestive systems still maintain favoritism for foods that your blood type ancestors ate. We know this because of a factor called lectins, which are abundant and diverse proteins found in foods that have agglutinating properties that affect your blood and the lining of your digestive tract.

Lots of germs, and even our own immune systems, use this super glue to their benefit. For example, cells in our liver's bile ducts have lectins on their surfaces to help snatch up bacteria & parasites. Bacteria & other microbes have these on their surfaces as well, and work rather like suction cups, so they can attach to the slippery mucosal linings of the body. Often lectins used by viruses or bacteria can be blood type specific, making them a stickier pest for those of that blood type.

Here's an example of how a lectin agglutinates in the body. Let's say a Type A person eats a plate of lima beans. The lima beans are digested in the stomach through the process of acid hydrolysis. However, the lectin protein is resistant to acid hydrolysis. It doesn't get digested, but it stays intact. It may interact directly with the lining of the stomach or intestinal tract, or it may get absorbed into your blood stream along with the digested lima bean nutrients.

Different lectins target different organs and body systems. Once the intact lectin protein settles someplace in your body, it literally has a magnetic effect on the cells in that region. It clumps the cells together and they are targeted for destruction, as if they, too, were foreign invaders. This clumping can cause irritable bowel syndrome in the intestines or cirrhosis in the liver, or block the flow of blood through the kidneys, to name just a few of the effects.

Lectins can also act as 'fake hormones,' latching onto the receptor for a hormone and either blocking the normal action of the hormone (this is called an 'antagonist') or revving up the hormone receptor non-stop (termed an 'agonist.')

Lots of information on lectins can be found on the internet. Unfortunately, the great majority of it is either extremely technical or just wrong to some degree or another. One common misconception is that all lectins in foods are inactivated either by heating, or through the process of digestion. This is true, but only to a certain degree. Some lectins, such as the ones from beans, are usually rendered inactive by slow and long cooking, but this may not result in all lectins being inactivated. Studies have shown that a percentage does tend to resist destruction, despite heating.

Other lectins, such as the ones from bananas, actually become more potent after heating. Digestive juices can inactivate lectins, but many people don't have the levels of stomach acid to do this.

If you currently suffer from digestive problems, it is more than likely that you have some degree of lectin sensitivity, and following the diet prescribed for your blood type is the best way to start the healing.

Signs you might be experiencing problems from lectins in your diet:

Bloating and flatulence after meals

Changes in bowel habits

Achy joints and muscles

Hormonal fluctuations

Skin eruptions

Fatigue and tiredness

This is not to say that you should suddenly become fearful of every food you eat. After all, lectins are widely abundant in legumes, seafood, grains, and vegetables. It's hard tobypass them. The key is to avoid the lectins that agglutinate your particular cells, determined by your blood type. For example, wheat germ agglutinin, the most common lectin found in wheat, binds to the lining of the small intestine, causing substantial reactions and irritation in some blood types, especially Type O.

Common Foods to Avoid For Each Blood Type That Contain Harmful Lectins

Type O Type A Type B Type AB

Wheat Lima bean Chicken Corn

Soybean oil Tomato Corn Banana

Peanut Eggplant Soy Fava bean

Kidney bean Garbanzo bean Lentil Chicken

Many people with joint problems feel that avoiding the nightshade vegetables such as tomatoes, eggplant, and white potatoes seem to help their symptoms. That's not surprising, since most nightshades are very high in lectins.