I’ve overheard several of my fellow trainers ask their clients what their blood type is during the clients initial consultations. Things like that tend catch my attention as it is not the sort of question that I have historically asked. I am presently studying material in preparation for certification under the International Society of Sports Nutrition (ISSN) to deepen my knowledge of sports nutrition and presently hold a Fitness Nutrition Specialist designation under NASM. Never once in either of my studies has a reference or test question been put forth between a persons blood type and specific dietary needs. After hearing it several times I asked one of my co-workers why is that information needed?
What sort of nutrition science is this?
Turns out several of our trainers subscribe to the “Blood Type Diet.” This diet has been around for awhile and sales of the book still do well on popular online markets. The diets theory rests on the belief that because we have four possible blood types (A,B,O and AB) we function best with four separate dietary needs. Apparently Rh factor (+ or -) is a non-issue, all that matters is the red stuff.
“Today’s workout will begin with a series of neck stretches.”
Although we have different blood types, as a species we only have one digestive system right? That’s what I thought, so I started to do a little digging into my nutrition books and hit up a few credible internet sources. Based on what I could find the medical community and nutrition guidance organizations have all reached the following conclusion:
The author relies purely on anecdotal evidence. His statements contain some factual flaws and there is no medical/scientific literature supporting his belief. But what about the people who claim that the diet has worked wonders for them?
Even a broken clock is right twice a day.
In the interest of fairness and having reviewed the food recommendations per blood type, I can state the author is recommending a whole food diet that is generally healthy, with some blood types having more restrictions than others. I don’t see anything particularly harmful in following the food recommendations. As stated previously here on MyTrainerChris, a diet should be something you can live with, live on and most importantly do no harm.
“Let food be thy medicine”
Correct me if I’m wrong on this, but doesn’t cleaning up your diet generally lead to feeling better? Not only that, but often when people make the effort to clean up their diet they often pick up other healthy habits such as increasing hydration, getting better sleep and exercising regularly. So is it in the blood type or the lifestyle choice?
Not only does the author suggest that certain food types match your blood type, that certain methods of exercise match your type as well. According to the author, based on my blood type I should stay away from meat and do best with calming exercises or cardio. Wait….cut CrossFit and Resistance training and toss out my bison, chicken and fish?
“I will give you my bacon when you take it from my cold dead hands.”
“But Chris, don’t blood tests have some bearing on nutrition?” Certainly! a blood test reveals many things including hemoglobin A1C, Blood Sugar levels, cholesterol levels, vitamin/mineral deficiencies and kidney/thyroid/liver functions among other things. This a very handy means of checking your health status and something that is commonly performed in clinics around the world.
Does this mean that the Blood Type diet is pure fiction? At present, there has been no scientific research to support the authors position. This does not mean he will not be proven correct in the future, just that the medical and scientific community at large disagree with his position.
American Journal of Clinical Nutrition
NYU Lagonne Medical Center