“We’re not so different”: Personalized blood type diets debunked in plant-based analysis

08 Dec 2020 --- Blood type is not associated with the effects of a plant-based diet on body weight, body fat, plasma lipid concentrations or glycemic control. This is according to a study from the Physicians Committee for Responsible Medicine, which investigated the diet made popular in the 1990s as an early step toward personalization.

The blood type diet recommends a mainly plant-based diet for those with blood type A, while it recommends a diet heavy in meat for people with blood type O.

However, the researchers found that the plant-based diet was beneficial for people of all blood types, and there was no evidence that meaty diets are good for anyone.

“Blood type was useless as a predictor of who would do well. It looks like a healthy plant-based diet is a really good prescription for everyone,” study author Dr. Neal Barnard, president of the Physicians Committee, tells NutritionInsight.

In the end, people are “not so different.” Barnard says that in the same way all cats are carnivores, great apes are mostly or entirely herbivores. “Like it or not, that is our biological family.”There are some slight health differences that relate to blood type.

In question for a quarter of a century
In general, Barnard explains that there are slight health differences that relate to blood type. For example, people with blood type A are slightly more likely to develop heart disease compared with type O. 

“The difference is not great, but it’s real. That seems to have led people to imagine that people with different blood types needed different diets.”

Specifically, a 1996 book called Eat Right for Your Type attracted many readers to the notion that a person with blood type A would do well on a vegetarian diet rather than a meaty diet. 

It also posited that the reverse would be true for a person with type O blood who supposedly would need meat and would not do well as a vegetarian or vegan, explains Barnard. 

He acknowledges that the appeal of blood type diets is understandable. “Many people have tried to understand why some people seem to get faster results with certain diets, while others get slower results.” 

“People also have different tastes. It is appealing to imagine that perhaps your body actually needs a candy bar or a fried chicken wing.”

Encouraging results for plant-based
The randomized control trial, published in the Journal of the Academy of Nutrition and Dietetics, included 244 overweight participants with no history of diabetes. 

For 16 weeks, half of the participants followed a low-fat, plant-based diet, while the other half made no diet changes. All in all, 68 intervention-group subjects were blood-typed and were deemed to provide an adequate sample as called for by a power analysis. 

The plant-based diet was found to ramp up metabolism – as measured by an increase in after-meal calorie burn – by 18.7 percent, on average, for the intervention group over the control.

This adds to a host of studies finding that aspects of vegetarian lifestyles can help with factors, from coronary heart disease to metabolism and diabetes. 

However, a recent investigation also found that vegans, vegetarians and pescatarians are up to 43 percent more likely to suffer bone fractures compared with those who eat meat and dairy.Plant-based diets were found to ramp up metabolism for all participants, regardless of blood type.

Blood types prove disappointing
Meanwhile, there were no significant differences in any outcome between individuals of blood type A and non-A, or between individuals of blood type O and non-O. 

Mean body weight change was -5.7 kg for blood type A participants and -7.0 kg for non-A participants. For type O participants, it was -7.1 kg in comparison to -6.2 kg for non-O participants. 

Mean total cholesterol decreased 17.2 mg/dl in the type A group and 18.3 mg/dl for non-A participants. It decreased 17.4 mg/dl among type O participants and 18.4 mg/dl for non-O participants.

“There are certain rules that apply across the board. Smoking is bad for everyone. Meat and dairy products have untoward effects, too. We are best-off putting vegetables, fruits, whole grains and legumes front and center on our plates,” recommends Barnard.

This type of universal recommendation is in contrast to a consumer desire for increasing levels of personalization. 

Industry has responded with a plethora of NPD, ranging from Lumen’s portable device to measure metabolism to personalized supplements from companies like Persona and Pharmavite. 

Personalization is also trickling into the infant nutrition sphere, as well as being a major pillar in DSM’s new strategy. 

By Katherine Durrell