A recent question posed to an internet dietician Mary Hartley sparked some outrage over on the www.dadamo.com message boards and got me thinking:

Is there any truth to the diet based on blood type?

For example, O blood type should eat more protein and AB blood type should eat more veggies.

Answer

The Blood Type Diet is outlined by Peter D’Adamo in Eat Right 4 Your Type, a diet book that has been a bestseller for over 10 years. Mr. D'Adamo asserts that your blood type is the key to your immune system, and by eating particular foods according to your blood-type, you can lose weight and prevent diseases, such as cancer, asthma, arthritis, diabetes, and others. But truthfully, there is no scientific evidence to back the authors claims, and the diets recommended for some blood types could produce nutritional deficiencies. The Blood Type Diet is just another fad diet.

Many dieticians embrace and use the research behind the Blood Type Diet, so it is not a complete and absolute truth to claim that registered dieticians (RD) know almost nothing about nutrigenomics and genetic based nutrition. However, based upon a series of interviews conducted in Holland among Dutch dieticians, it's not far from the truth:

Based on the analysis of 51 face-to-face interviews with Dutch dietitians in April 2006, it can be concluded that awareness and knowledge on nutrigenomics is low. Almost half of the interviewees had heard of nutrigenomics and nutritional genetics, but most could not explain what either were about.

Clients of more than half of the interviewees bring up the topic of heredity or family history during consultations in regard of nutrition-related diseases such as weight and diabetes. Clients almost never ask questions related to genetic testing but, if they do, it is in the context of hyper-lipidemia, hyper-cholesterolemia and other metabolic disorders.

More than half of the dietitians thought genetic testing would be relevant for dietetic practice. Most, however, experienced difficulties with identifying the practical implications of nutrigenomics. They expected nutrigenomics to offer opportunities for dietetic practice through tools for creating more personalized or individual dietary advice and prevention of diet-related ill health. Some dietitians expressed concerns about cost, the current lack of evidence, and the affect on clients’ attitudes whilst other felt they knew too little to identify their concerns.

In line with these concerns, there is feeling that nutrigenomics is not relevant to dietetic practice because of a lack of evidence, anticipated costs of testing, and the existing potential for treatment without genetic testing.

When I read these critiques from people who are supposedly experts I simply marvel at the degree of self-assurance they display despite what appears to be a complete ignorance of the subject. There is enough science behind the use of blood type as a dietary determinant to choke a horse; maybe two or three horses. However, if you don't like the conclusions (or more likely don't like who or where they came from) go ahead and criticize the science. That never fails to buy a bit of time.

I also get a bit skittish when someone who is trying to convince me of something starts their sentence off with 'Truthfully...'

The line about the diets producing nutritional deficiencies is complete twaddle. There is no proof of that whatsoever. I challenge Ms. Hartley to back up her assertions with some sort of evidence, or lacking that have the courage to retract this ridiculous statement.

Reminds me of the quote by Upton Sinclair:

If is difficult to get a man to understand something when his salary depends upon his not understanding it.

Speaking of fad diets, many dieticians still cling to the low-fat (or should I say 'fat-phobic') fads of the 1980's. There is perhaps perverse justice in a vignette I recently read in David Stafford's terrific new book Endgame, 1945. Stafford writes that after the outcry against the Nazi euthanasia program, the experts merely moved their lethal expertise away from gas to starvation:

The asylums and hospitals reverted instead to the murdering of the handicapped through lethal injection and deliberate starvation. The director at Kaufbeuren, Dr. Valentin Falthammer, was an especially keen and energetic supporter of the program, and proudly introduced a carefully crafted fat-free diet that guaranteed death to his patients and economized on pharmaceuticals. The death rate rose so high that local authorities forbade the ringing of church bells at funerals, so as to not alert the local population.

Like Peter Gabriel said three decades ago:

It's only knock and know-it-all,
but I like it.

Spent the weekend in Phoenix/Scottsdale where I lectured to the Arizona Naturopathic Medical Association. Nice crowd; surprising to me was the fact that MDs outnumbered NDs at the morning professional session. Had way too much material. The professional lecture was supposed to last four hours, and by midpoint I realized that I actually had about nine hours worth of material, forcing a truncation which certainly had nothing to do with any lack of science.

Happily, this probably means that my presentations for IfHI 2009 are already complete.

Here is a short film about the epigenetic landscape that I made for the lectures. Enjoy.