Thursday, March 16, 2006

Sceptical about... Blood types and diet

I read a report in the Daily News recently of the proceedings at a “food security” conference held recently. Apparently the big issue were diets for people with different blood types.

Yet again I think we’re in danger here. In danger of believing something that is nonsense. Utter nonsense. Let me state this in very clear and simple terms. There is absolutely no evidence that blood type has anything to do with the body’s reaction to the food it consumes. None.

The theories that were presented at this conference were based on the books written by a father and son team, Drs James and Peter D’Adamo. In their books they claim that they have collected “over 1,000 scientific articles on blood types and their correlations to disease, biochemistry, nutrition, and anthropology”. Yet strangely not one of them has been under controlled scientific conditions. All they have is a series of anecdotes along the lines of “Well, it helped my Aunt Alice, so it must work”. It’s just like those people you meet who had an aged relative who smoked until he was 105 years old, so smoking can’t be dangerous.

If there is real evidence for these theories, evidence that came from strictly controlled scientific studies, not just a few cases where improving someone’s diet made them healthier, then I can’t find it. Where is it? My challenge to the blood type food faddists is show us REAL evidence, not just anecdotes.

The simple truth is that many of the dietary recommendations the D’Adamos make would work for many of us. They suggest that certain groups should consume less fat. OK, so who wouldn’t benefit from that?

However what’s not often mentioned by people selling the bizarre ideas from the D’Adamo family business is that they took it further than just diets. They suggest that even our personalities are affected by our blood types. Apparently those of us who have type O blood have “strength, endurance, self-reliance, daring, intuition, and innate optimism...". Those of us unfortunate enough to be type A are “poorly suited for the intense, high-pressured leadership positions at which Type O's excel” and “become anxious and paranoid, taking everything personally”.

Curiously the big period in history for research into the personality aspects of blood types was during the lowest point in European history, namely during Nazi Germany. It was found to be rubbish then and it remains rubbish today.

The trouble with this sort of pseudoscientific claptrap is that it leads into a profoundly dangerous area – group stereotypes. You know the sort of thing. Europeans are clever and industrious, Jews are scheming and money-grabbing and that Africans are just lazy. We all know how dangerous that can be. Oh, and it’s just plain incorrect as well.

The best summary of the blood group and diet issue that I’ve come across was made by Dr Victor Herbert (a real doctor) from the Mt Sinai Medical Centre in New York. He said that it is “pure horse manure. It has no relation to reality. The genes for blood type have nothing to do with the genes that handle the food we eat”.

I urge everyone to treat this and other pseudoscience with the contempt it deserves.

1 comment:

thakadu said...

Listen here you, I bet you are blood type O negative and don't you know that your blood group has many more genes for scepticism. I should know because I have personally met at least three other type O negatives that were sceptics!