You may have heard about the Blood Type Diet. It calls for eating certain foods and avoiding others based on your blood type of A, B, AB, or O. It was originally created by naturopath Peter D’Adamo, who believes that the foods you eat react chemically with your blood type. This can affect how efficiently you digest food. “If you follow a diet tailored to your individual blood type, according to D’Adamo, you can essentially biohack your genetics, lose weight, have more energy, and help prevent disease,” explains Eliza Whetzel, registered dietitian at Middleberg Nutrition specializing in weight management, sports nutrition, food allergies/intolerances and GI disorders. “Your blood type is a key genetic factor that can influence your risk factors for disease, the way you respond to stress, and, according to Dr. D’Adamo, how to optimize your nutrition.”
What does it really mean to eat for your blood type, and how does it all work? We talked to nutrition experts to better understand this diet and how the eating behaviors of each blood type break down.
Eating for Blood Type A
According to Lisa Samuels, R.D., hatha yoga teacher and founder of Happie House Yoga in Queens, New York, blood type A adapted based on the evolutionary need to begin farming and harvesting grains for survival instead of hunting game. “Those with type A blood have a lower level of acid in the stomach. [This] makes it more difficult to break down substantial proteins,” she explains. “They also have a high level of a digestive enzyme that’s responsible for breaking down sugars and carbohydrates.”
Therefore, type A blood thrives on a meat-free, all-natural, vegetarian diet. According to Samuels, type A’s should consume more whole grains, fruits, vegetables, and legumes.
Eating for Blood Type O
According to D’Adamo, people with blood type O have a tendency to be more acidic. This means they can better digest foods that contain protein and fat. “Simple carbohydrates, such as foods made with white flour, are easily converted to fat in the body. [This] can cause inflammation and other autoimmune conditions,” Samuels explains. “This is because people with type O blood contain higher amounts of the enzymes used to digest these two nutrients.”
Therefore, she says it’s best for individuals with type O blood to stay away from simple carbs, especially grains and lectins. They should stick with a diet high in lean protein, such as fish, chicken, pork, and lean cuts of steak. Additionally, they should consume vegetables and whole grains (such as brown rice, quinoa, millet, barley, etc.).
Eating for Blood Type B
History shows that blood type B developed mostly in parts of Asia such as Pakistan and India. According to Samuels, those with type B blood exist “in the middle” of those with type A and type O. “They strive when they’ve found a sense of balance. [They] do not do well with extremes because they produce higher levels of the stress hormone cortisol,” she explains. “Therefore, it is best for those with type B blood to adapt an omnivorous diet, eating equal amounts from both the plant and animal realms.”
The best foods for this blood type are green vegetables, eggs, meat, and dairy. Chicken, corn, buckwheat, lentils, tomatoes, peanuts, and sesame seeds should be avoided.
Eating for Blood Type AB
Blood type AB is rare, claiming less than 5 percent of the population, according to D’Adamo. “This blood type is unusual in that it can sometimes act more like type A and sometimes more like type B,” Samuels says. “They have the low stomach acid of blood type A combined with blood type B’s affinity for meat. However, the meat gets stored as fat because there isn’t enough acid to digest it.”
For these reasons, seafood tends to be the best protein option for folks with this blood type. Samuels recommends mahi-mahi, tuna, and red snapper. “A small amount of dairy is beneficial, as well,” she adds. “AB’s should also avoid caffeine, alcohol, and cured and smoked meats such as salami or bacon.”
Does the Blood Type Diet really work?
It’s important to note that anecdotal evidence may support the benefits of the Blood Type Diet. However, scientific evidence is scarce. In fact, one 2014 study published in PLOS One, which examined more than 1,450 healthy adults who followed the Blood Type Diet, came up short. “Although some of the diets had a positive effect on factors such as body mass index (BMI) and triglyceride (blood fat) levels, it was independent of the participant’s blood type,” explains Toby Amidor, M.S., R.D., Wall Street Journal bestselling author of the upcoming Smart Meal Prep for Beginners. “These results show that the foods recommended for a particular blood type aren’t necessarily the best way for you to eat in order to achieve long-term health.”
Bottom line: You can still improve your health by following a nutritious eating plan that isn’t specific to your blood type.