The idea behind the diet plan in Eat Right 4 Your Type, also called the blood type diet, is that following a diet and lifestyle that suits your blood type will make you healthier, help you reach your ideal weight, and even slow down the aging process. That’s according to the author of the book Eat Right 4 Your Type, the naturopathic physician Peter J. D’Adamo, MD. Eat Right 4 Your Type was originally published in 1996 and quickly hit major bestseller lists, and since then, Dr. D’Adamo has published a number of books on the diet, including Live Right 4 Your Type and Change Your Genetic Destiny.

“The concept of the Eat Right 4 Your Type diet is that blood types have evolved through the evolution of man,” says Chicago-based David Grotto, RD, the owner of David Grotto’s Nutrition Housecall and author of The Best Things You Can EatThe thinking goes that “most [people] were type O — hunter-gatherers with a predominantly animal-protein-based diet.”

 

How Does the Blood Type Diet Work Exactly?

D’Adamo says that protein components in food called lectins bind with antigens on blood cells and lead to blood cell clumping, or agglutination. Avoiding agglutination, D’Adamo argues, can improve health by helping people manage weight better and fight cancer and heart disease.

Liz Weinandy, RD, at Ohio State University Wexner Medical Center in Columbus, Ohio, says that lectins can be dangerous to our health if eaten in large amounts, but the way D’Adamo presents their effects may be misleading. Reducing their potential health harms is relatively easy: For example, lectins found in beans can be eliminated simply by soaking the beans in water for a few hours and then boiling them for 10 minutes, Weinandy says.

But D’Adamo uses his theory to develop separate diets for people with blood types A, B, AB, and O. In addition, he recommends exercise and overall healthy habits, like drinking enough water, Weinandy explains. However, the diet is specific about which foods groups are allowed for different blood types — and that can be be restrictive, Weinandy says.

In fact, while people often have different nutritional needs, humans are complex animals, and chalking up these specifics to blood type may oversimplify those needs, Weinandy says. “To base a whole diet on that is probably not very sensible,” she says.

Is There Any Scientific Evidence to Support That the Blood Type Diet Is Effective?

While Eat Right 4 Your Type might help with weight loss, as any calorie-restricted diet would, whether it has more significant health benefits than another eating approach is another matter entirely. Critics of the plan argue there is little to no science to back up the theory that eating according to blood type can improve your health.

“What do clumping blood cells have to do with weight? I can understand heart disease and risk for blood clots,” Grotto says, “[but] as far as I know, there is no science to support the connection of agglutination and obesity, cancer, and so on.” Weinandy agrees, noting that many of the claims in the book are not scientifically proven.

In fact, an article published in January in 2014 in PLOS One found no support for the blood type diet’s claims that adherence could improve health and lower the risk of chronic disease. (1) Researchers analyzed surveys from 1,455 study participants and found that while some people benefited from sticking to a particular diet, this was actually independent of their blood type. For example, people following the type A diet tended to have a lower body mass index (BMI) and blood pressure than other study participants, regardless of whether they themselves had type A, type B, type AB, or type O blood.

A Food List for Each Blood Type: What to Eat and Avoid

If you’re interested in exploring the eating plan, here’s an outline of what foods you should eat and stay away from based on each blood type:

  • Type O: If you are type O, like an estimated 46 percent of the population, the Eat Right 4 Your Type program suggests that you stay away from wheat, dairy, caffeine, and alcohol. Reach instead for fruits, vegetables, and lean, organic meats. (2)
  • Type A: People whose blood is type A are steered toward a vegetarian diet, including soy proteins, grains, and vegetables. They are also encouraged to eat organic and fresh food in as natural a state as possible. (3)
  • Type B: People whose blood is type B are identified as omnivores who can eat a variety of foods. They should avoid certain foods — like corn, wheat, buckwheat, lentils, tomatoes, peanuts, sesame seeds, and chicken — and instead opt for goat, lamb, mutton, rabbit, green vegetables, eggs, and low-fat dairy products. (4)
  • Type AB: People whose blood is type AB should choose tofu, seafood like mahi-mahi and salmon, dairy like yogurt and kefir, and green vegetables like kale and broccoli. They should avoid caffeine, alcohol, and smoked and cured meats, and try to eat more small meals throughout the day, according to the diet. (5)

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