A Review of the Blood Type Diet: What Do Genetics Have to Do With Eating and Weight Loss?

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. (5)

Here is a sample one-day diet for each blood type, based on D’Adamo’s recommended recipes: (6)

Type O

• Breakfast Two slices of organic bread with almond butter, vegetable juice, and a banana
• Lunch A spinach salad with roast beef and fruit slices
• Snack Fruit
• Dinner Lamb stew with a variety of vegetables
• Dessert Fruit salad

Type A

• Breakfast Buckwheat pancakes topped with maple syrup, tahini, jam, or lemon juice
• Lunch Curried peanut tempeh with carrots, celery, and broccoli
• Snack Trail mix
• Dinner Rice pasta with feta and greens
• Dessert Crumb apple pie

Type B

• Breakfast Oatmeal with unsalted butter or ghee
• Lunch Indian curry salad
• Snack Kale chips
• Dinner Apple-braised lamb shoulder chops
• Dessert Carob fudge

Type AB

• Breakfast Silken tofu scramble with carrots and zucchini
• Lunch Cream of mushroom soup
• Snack White bean hummus with celery sticks
• Dinner Grilled cod and veggies over apricot-walnut couscous
• Dessert Flourless almond butter and raisin cookies

“I have no problems with the blood type A recommendations, which is a plant-based diet,” says Grotto. “Overall, the recommendations are good for most of the blood types.”

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.

There’s concern that the Eat Right 4 Your Type diet for those with blood type O is too protein-heavy. “Animal protein, especially red meat, has been linked to health problems, such as heart disease and colorectal cancer,” says Grotto.

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 who is based in 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.

“Whatever you do to lose weight, it has to be reasonable to be sustainable,” Weinandy says. She notes that the blood type diet may work for some people, but given how restrictive it is, people may have trouble sticking with it long term — and thus not be able to keep off the weight they lost.

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.