“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 Eat. The thinking goes that “most [people] were type O — hunter-gatherers with a predominantly animal-protein-based diet.” 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. “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.
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)
Type O
Breakfast: Two slices of organic bread with almond butter, vegetable juice, and a bananaLunch: A spinach salad with roast beef and fruit slicesSnack: FruitDinner: Lamb stew with a variety of vegetablesDessert: Fruit salad
Type A
Breakfast: Buckwheat pancakes topped with maple syrup, tahini, jam, or lemon juiceLunch: Curried peanut tempeh with carrots, celery, and broccoliSnack: Trail mixDinner: Rice pasta with feta and greensDessert: Crumb apple pie
Type B
Breakfast: Oatmeal with unsalted butter or gheeLunch: Indian curry saladSnack: Kale chipsDinner: Apple-braised lamb shoulder chopsDessert: Carob fudge
Type AB
Breakfast: Silken tofu scramble with carrots and zucchiniLunch: Cream of mushroom soupSnack: White bean hummus with celery sticksDinner: Grilled cod and veggies over apricot-walnut couscousDessert: Flourless almond butter and raisin cookies
Also, the Eat Right 4 Your Type diet does help people reduce calories and can lead to weight loss. “Unlike a lot of other fad diets, the general advice is good,” Grotto says. “I have dealt with patients who say they feel better after following the diet.”
Can the Blood Type Diet Help People With Certain Conditions?
But there is some evidence that people with certain blood types may be more prone to certain illnesses. For instance, “individuals with type O blood may be at a greater risk for duodenal ulcers. Those who are type A may be at an increased risk for atrophic gastritis,” says David J.A. Jenkins, PhD, MD, the Canada research chair in nutrition and metabolism at the University of Toronto. Some blood type O patients have specific proteins that are attacked by the bacteria Helicobacter pylori, which is commonly linked to ulcers. Similarly, that bacteria has also been associated with atrophic gastritis, though the exact relationship between type A blood and atrophic gastritis is not known. But there’s no evidence to support the theory that eating a diet tailored to a certain blood type has any effect on these conditions, Dr. Jenkins says. Also, dietitians say it’s possible that individuals may experience nutritional deficiencies when following the eating plan. “The Eat Right 4 Your Type diet recommends calcium supplements for [type O and type A individuals] who can’t eat dairy, for example,” says Amy Jamieson-Petonic, RD, a pediatric and sports dietitian at University Hospitals Cleveland Medical Center who is based in Akron, Ohio. “But you can only absorb a certain amount of calcium from supplements, and you get so much more from food. If you follow this diet for a long time, you could experience vitamin and mineral deficiencies.” Another potential long-term problem with the blood type diet is a drawback common to many diets: Restriction leads to boredom. “When you take away favorite foods, it’s almost a death knell for any dietary program, whether there is solid advice or not,” Grotto says. “If you tell people to avoid fruit or anything made with white flour, they can go back to those foods with a vengeance later on.” Some critics argue that Eat Right 4 Your Type places too much emphasis on blood type and fails to take into account individual differences. “I would look at an individual’s food preferences and health challenges, such as stroke risk, hypertension, and allergies,” Grotto says. Still, for people curious about the benefits of the blood type diet, Weinandy sees no harm in trying it for a short period of time. “More important, make sure that you are eating wholesome foods that are not processed,” she advises, noting that she often directs patients more toward a Mediterranean diet or a DASH diet for overall health and weight loss. Additional reporting by Stephanie Bucklin
