Nutritionists Say Science Doesn't Back 'Blood Type Diet'
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What if information as simple as a person’s blood type could determine exactly what foods work best with their unique body chemistry?
That’s exactly what the blood type diet promises to do. Originally developed in 1996 by naturopathic doctor Peter D’Adamo, the diet has picked up momentum in recent weeks on social media.
While the premise of the diet is intriguing, two dietitians interviewed by Heathline say there isn’t enough scientific backing to endorse the blood type diet.
“There’s just not the science to support it, so we don’t look at blood type in making those considerations,” Liz Weinandy, a staff dietitian at The Ohio State University Wexner Medical Center, told Heathline. “Looking at someone’s blood type definitely tells us something about the person, but should it dictate the foods that they eat? Probably not.”
The blood type diet asserts that blood type can determine which foods will work best with a person’s internal chemistry.
For example, those with type O blood are said to do best with a largely plant-based diet with lean meats, cutting out wheat and dairy.
For those with type A blood, the diet recommends carbohydrates and cutting out meat.
Type B and type AB blood are said to work best with a balanced omnivorous diet.
Dietitian Kristin Kirkpatrick, MS, RD, LD, manager of wellness nutrition services at the Cleveland Clinic Wellness Institute, told Healthline that many of the foods recommended in the blood type diet are healthy, but there isn’t enough scientific evidence to support following the diet to the letter.
“My advice to clients is this: If a certain blood type diet also happens to be a whole foods diet that has plenty of plants, lean proteins, healthy fats, and void of white grains and sugar, then by all means follow it,” said Kirkpatrick. “But if a particular diet for your blood type suggests that you cut out food groups, or buy special foods, then like any diet, it’s probably not the best approach from a sustainability factor.”
“It’s all the foods that have been shown to be healthy, but the research isn’t there to support it,” she noted.
Does blood matter?
Blood testing is an important diagnostic tool in the field of medicine.
It can give health professionals a useful snapshot of a person’s overall health.
“I definitely look at blood work, looking specifically for vitamin and mineral deficiencies, plus to see how well kidneys and liver are functioning, so I always take a look to assess which direction I need to go and what their dietary needs are,” said Weinandy.
While there isn’t enough scientific evidence to endorse the blood type diet, there are still plenty of unknowns when it comes to the relationship between blood type and overall health.
Kirkpatrick points to a study that shows a connection between certain blood types and the risk of type 2 diabetes as well as heart attacks.
She also notes that she’s become an expert in the field of nutrigenomics, or genotypes that do impact the diet.
“I still don’t believe that we should structure our food choices based on our blood type,” said Kirkpatrick. “This will always be a popular approach, but I’m not sure the science has caught up with the enthusiasm. I realize the popularity may also increase with these new studies showing heart attack and diabetes risk, but any dietary factors are not mentioned in these studies.”
Go for lifestyle choices
Both dietitians interviewed by Healthline note that the blood type diet contains many foods — particularly fruits and vegetables and lean meats — that are beneficial to a person’s overall health.
But as any dietitian will tell you, the key is to make meaningful dietary choices and continue them — not to follow a crash diet for a few weeks and then revert.
“When you talk about weight loss, a diet does not work. What does work is a lifestyle change,” said Weinandy. “I would usually take people back to the Mediterranean diet or a variation of that. In the United States, we teach a lot of the Mediterranean diet, but we also teach a lot of the DASH (Dietary Approaches for Stopping Hypertension) diet — they’re really very similar.”
Weinandy also points out that many of the foods included in the blood type diet are also part of the two healthy diets she mentioned, but that parsing things by blood type doesn’t really make sense.
“We’re looking for what’s beneficial for human health, and that’s regardless of blood type or bone structure,” she said. “We’re all one species, humans are all the same species, and really, we know the basics of a healthy diet for our whole species: mostly whole foods and plant-based.”