What about the blood type diet?  I do believe there is some truth to it , particularly with generalizations such as A blood types tend to be more vegetarian, B blood types do well with fish and lamb but should avoid chicken, O blood types need more protein etc.  But it is not necessarily something to pay much attention to or to utilize strictly.   Because people differ not only by blood type, but by constitution, medical health, if someone is has a hotter constitution or a colder one….these things are not about blood type. 

And in general it is not good to think that you have to strictly stick to a particular diet.  However, if there is a certain food that you know is not good for you (such as chicken for B blood types) try to avoid that since it may have negative health affects.

However, you don’t need to eat fish all day or lamb if you don’t like those foods.

Besides, unfortunately, the quality of much food nowadays is not great so eating low quality foods that may normally be good for a certain blood type is not going to improve health. More than the blood type diet, I would recommend a balanced diet and healthy diet.  And everything in moderation.  That is really the key to balance and good health.