Science Questions

Do blood group diets work? Natasha Singh

Chris -   I guess we can ask this in two ways:  One is - Where do different blood groups come from?  And is there any evidence that eating a certain diet, if you have a certain blood group, has any kind of physiological evidence that it's any use?

Nina -  Well blood groups, of course, are related to the types of antigens, these proteins present on the surface of our red blood cells.  We have, for instance, high concentrations of A blood type in Europe, O in Asia, B in the Mediterranean area and so forth.  The problem is that you find lots of geographic heterogeneity in blood types, and so if you go to the circum-Mediterranean for instance you'll find not only B blood types, but A and AB and O as well.  And so the idea of there being pure blood types in any one area is not very good.  And, perhaps the most important thing is because of this these blood type related diets, basically, are rubbish.  In any given geographic area, there will be people with various blood types that will have shared other aspects of their environmental history.  For instance, many people living in Britain today, there will be a moderate percentage of A blood type, but also many other blood types there, they will have shared a common agricultural background, eating dairy products and so forth.  Lets say if they have O blood type, according to the blood type diet they should eat a particular type of diet, but in fact all of those Os, As and ABs all descended from people with a similar farming and dairy background.  That recent experience, regardless of their blood type, is going to be more important to determine what kind of diet they should eat today.

So pay attention to where your ancestors lived, as opposed to what their blood type is.

May 2009