Wednesday, April 29, 2009

The Blood Type Diet

The blood type diet was developed by Peter D'Adamo in his book 'Eat Right 4 Your Blood Type'. D'Adamo is a natural health practitioner who considers that the most important factor in determining a person's ideal diet is their ABO blood type.

What Does It Involve?

The diet considers that food lectins react differently with different types of blood, some creating antigens which cause a reaction as if to an allergen or invader. Therefore you are advised to consume more of some foods and avoid others according to whether you have A, AB, B or O type blood.

Group O, The Hunter: this is claimed to be the oldest blood type. A high protein diet is recommended.

Group A, The Cultivator: more vegetables, very little red meat, would suit a vegetarian diet.

Group B, The Nomad: most foods including dairy. The other blood groups are not recommended to eat dairy products.

Group AB, The Enigma: intermediate between A and B.

On top of that, there is a long list of foods that should not be eaten for each blood type because of the action of the lectins.

Does It Work?

D'Adamo claims to have around a 70% success rate in terms of improved health conditions and/or weight loss. However, these results do not come from independent research but are self-reported, e.g. people who respond to polls. There is no way of tracking all of the people who have read his books and tried the diet, so there is no analysis of their results. The diet does not seem to have had any structured clinical trials.

Where results are good, this may be because the diet happens to suit those people or it may be that simply becoming more conscious of what they eat and avoiding certain foods helps them to lose weight and regain health.

Only around 10% of the population have group B blood, so 90% of people will be in the other groups where dairy products are not recommended. If you read the packaging you will be surprised to see how many processed foods contain milk in some form, including milk solids, lactose and whey. Avoiding dairy products will automatically cut out a lot of the fat, fast food and junk food in the average person's diet, and can result in weight loss by itself.

Any Negatives?

D'Adamo has been heavily criticized for the lack of structured research to back up his ideas. Virtually all independent research suggests that there is no link between blood type and diet.

Additionally, many scientists consider that lectins in foods do not act in the way that extracted lectins might act. That is, when they are included in food they do not set off a hostile reaction with antigens or antibodies. Research has not found a link between blood type and food allergies either.

If you like a diet with a lot of rules that sets out clearly what you can and cannot eat, this may suit you, but you have to be prepared to work with the complexity of it. Some versions of the diet will not suit some people and as always you are recommended to discuss it with your doctor before starting on the blood type diet.

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