Blood Type Diet: Does It Work?
While the blood type diet may sound like something out of a young-adult vampire series, plasma doesn’t actually make an appearance on the food list (phew). Instead, it’s a strategy for eating that’s based on your own particular blood type.
Proponents believe your blood type determines how well you can process certain foods. They contend that each of the four basic blood types carry different traits and characteristics that can influence everything from weight management to longevity. But does eating according to your blood type really work? We took a look at the research to find out more.
What Is the Blood Type Diet?
The blood type diet is the brainchild of naturopathic doctor Peter D’Adamo. In 1996, he published Eat Right 4 Your Type, a book that detailed his hypothesis on the interrelationship between blood type, diet, and overall health. D’Adamo believes that each of the four principal blood groups can be linked to specific characteristics, disease risks, and personalities.
Following D’Adamo’s blood type diet protocol involves using a home kit to find out your blood type (if you don’t know it already), eating according to the meal plan designed for that blood type, and taking blood-type-specific vitamins and supplements. (Some advocates omit the supplementation portion of the plan.) While it’s often referred to as a weight-loss regimen, D’Adamo promotes following his blood type diet for living healthier overall.
What Should You Eat According to the Blood Type Diet?
While it’s called the blood type diet, D’Adamo’s plan extends beyond food, identifying lifestyle strategies for each blood type, too. For instance, D’Adamo believes people with different blood types should exercise differently, as well. He contends, for example, that type Os benefit from brisk regular exercise that taxes the cardiovascular and muscular skeletal system, while type Bs benefit most from exercise that challenges the mind and body, such as martial arts and golf.
For the purposes of this article, however, we’ll touch on the basic eating recommendations for each blood type. The foods chosen are based on how those of different blood types react to lectins, or carbohydrate-binding proteins found in many foods, especially grains and beans. Dr. D’Adamo explains that certain lectins can cause inflammation of the intestines that can mimic food allergies. The idea is that each blood type should avoid the lectins that can cause adverse reactions such as bloating, fatigue, and achy joints and muscles.
Blood type A diet
People with type A blood are instructed to:
- Eat a mostly vegetarian diet full of fresh and organic foods
- Eat smaller, more frequent meals
- Consume more protein at the start of the day and less at the end
Foods to add: Salmon, figs, soy milk, beets, portobello mushrooms, grapefruit, turnips, parsnips, lentils, kale, cod, spelt noodles, coffee
Foods to cut: Beef, banana, cow’s milk, tomatoes, eggplant, oranges, potatoes, garbanzo beans, cabbage, pork, wheat pasta, black tea
Blood type B diet
People with type B blood are instructed to:
- Avoid chicken and eat goat, lamb, rabbit, and venison instead
- Eat plenty of green vegetables, eggs, and low-fat dairy
Foods to add: Lamb, broccoli, oat bread, kidney beans, almonds, peppers, rice cakes/bran, olive oil, mozzarella cheese, cod, bananas, green tea
Foods to cut: Chicken, corn, wheat bread, lentils, peanuts, tomatoes, couscous, canola oil, American cheese, crab, coconut, coffee
Blood type O diet
People with type O blood are instructed to:
- Eat organic fruit, vegetables, and lean meats
- Avoid wheat, dairy, caffeine, and alcohol
Foods to add: Spelt and/or brown rice bread, almond milk, lean grass-fed beef, kale, cod, broccoli, turnips, parsnips, azuki beans, walnuts, olive oil, artichokes, pineapple juice
Foods to cut: Wheat and gluten, cow’s milk and other dairy products (e.g., cheese), pork, corn, catfish, cabbage, potatoes, navy beans, peanuts, canola oil, olives, orange juice
Blood type AB diet
People with type AB blood are instructed to:
- Eat tofu, green vegetables, and seafood
- Eat some dairy, especially cultured varieties such as yogurt and kefir
- Avoid caffeine and alcohol
- Eat smaller, more frequent meals
- Beware of certain food combinations. (For example, D’Adamo says, “You’ll digest and metabolize foods more efficiently if you avoid eating starches and proteins in the same meal”)
Foods to add: Turkey, pinto beans, mahi-mahi, kale, sweet potatoes, red snapper, spelt, cod, kefir, oatmeal, tuna, mozzarella cheese, sardines, eggplant, parsnips, pineapple, salmon
Foods to cut: Red meat, kidney beans, corn, white potatoes, buckwheat, sea bass, ice cream, corn flakes, American cheese, peppers, lima beans, mango
Does the Blood Type Diet Work?
When it comes to dropping the lbs, let’s get one thing clear: “Anything that ultimately cuts out heavily-processed, high-calorie foods and includes more whole food can result in weight loss,” says Beth Warren, RDN, CDN. But in terms of overall health — while eating plenty of whole foods is beneficial — you may miss out on other healthy foods on the blood type diet because you’re instructed to avoid them. “You could omit entire foods or food groups needlessly, which can lead to potential deficiencies over time,” Warren says.
Openfit Nutrition Manager Andrea N. Giancoli, M.P.H., R.D. has the same concerns about following any of the four blood type diet plans. “The blood type diet is not one that I would recommend to anyone because, A. There’s no scientific evidence to support the hypothesis, and B. It’s really restrictive,” she says. Giancoli explains that some people may find the blood type diet effective for weight loss because it eliminates certain foods — and can consequently lead to fewer calories consumed overall — but that they shouldn’t be fooled by the blood type angle.
There aren’t a ton of studies that examine the efficacy of eating according to your blood type, but one 2013 meta-analysis found no evidence to support the health benefits of blood type diets. While the researchers confirmed links between certain blood types and greater risks for certain diseases, food allergies and hypersensitivities, they didn’t find any substantiation for the health benefits of a diet based on blood type.
And, while studies in 2014 and 2018 found some blood type diets had a positive effect on cardiometabolic risk (meaning a person’s chance of diabetes, heart disease, or stroke), the association wasn’t actually related to the participants’ blood types. In other words, while the researchers found the Type-A diet was associated with lower body mass index (BMI), waist circumference, blood pressure, and cholesterol, for instance, the findings had more to do with eating a healthy diet than one tailored to a specific blood type. D’Adamo has challenged the 2014 study, citing major flaws in the methodology, and claiming that what the participants ate didn’t actually follow the blood type diet.
The short answer: “At this time, there isn’t valid research to support eating based on a person’s blood type with this specific dietary regimen,” Warren says. Giancoli’s on the same page: “There’s no good science to support that your blood type dictates the food choices you should be making.”
If eating healthier is your goal, the blood type diet may not be the most ideal, sustainable route for you. “There are plenty of plans that focus on whole foods a person can eat and get the advantages of this diet without denying food groups,” Warren says. If you’re looking for individualized diet advice, Giancoli suggests visiting a registered dietitian rather than turning to a diet program consisting of four inflexible plans.