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Medically reviewed by Suzanne Fisher, RDMedically reviewed by Suzanne Fisher, RD

The blood type diet suggests that eating certain foods based on your blood type can improve your health and help with weight management. Dr. Peter D’Adamo, a naturopathic physician, introduced the idea of the blood type diet in his 1996 book Eat Right 4 Your Type. 

D’Adamo believes that as humans have developed different blood types, each blood type can benefit from different diets over time. His theory is that your body digests food better if you eat the same types of foods that were common when your blood type evolved.

According to D’Adamo, following the blood type diet carefully can help you avoid common viruses and infections, lose weight, fight diseases like cancer and diabetes, and slow down aging.

However, most experts agree that there is little scientific evidence to prove that the blood type diet is actually effective. More research is ongoing, but it may help to know which foods can offer additional benefits to add to an already nutritious diet.

How the Blood Type Diet Works

Your blood type depends on the presence or absence of the A and B antigens (types of molecules) on the surface of your red blood cells. The four main blood types include:

• Type A: Only A antigens are present
• Type B: Only B antigens are present
• Type AB: Both A and B antigens are present
• Type O: Neither A nor B antigens are present

D’Adamo believes that the same antigens that determine your blood type can also be found in your gut. He suggests that these antigens interact with the food you eat, leading to different reactions and digestive processes depending on your blood type.

The diet claims that eating proteins called lectins that don’t match your blood type can cause your blood cells to clump together, leading to potential health conditions.

The Correlation Between Blood Types and Food

According to D’Adamo’s research, early humans commonly had type O blood and were hunters who ate mostly animal protein. For people with type O blood, he recommends a diet similar to the paleo diet, focusing on high-animal protein.

When humans moved from hunting to farming lifestyles, blood type A became more prevalent because they ate more plant-based foods. He suggests that people with type A blood should eat a mostly plant-based diet, as their ancestors were farmers who relied on this type of food.

The diet recommends a balance of different foods for those with type B blood. D’Adamo believes that people with type B blood descended from nomadic tribes that consumed more meat and dairy.

Finally, type AB is considered the “modern” blood type. For people with type AB blood, the diet suggests a combination of foods beneficial for type A and B blood. Experts believe that type AB blood evolved from mixing these two types of blood.

What Blood Type Do You Have?

To begin the blood type diet, you need to know if you have type A, B, AB, or O blood. You can ask your healthcare provider for a blood test or find out when donating blood.

Guidelines

The blood type diet categorizes foods into three groups for each blood type: highly beneficial, neutral, and avoid. Highly beneficial foods are considered medicinal, supporting health and well-being. Neutral foods are seen as safe to consume but without significant health benefits. Foods in the avoid category are thought to be potentially harmful for a specific blood type.

Each blood type diet includes twelve food groups:

• Meats and poultry
• Seafood
• Dairy and eggs
• Oils and fats
• Nuts and seeds
• Beans and legumes
• Grains and cereals
• Vegetables
• Fruits
• Beverages, teas, and coffee
• Herbs and spices
• Condiments, sweeteners, and additives

Things To Consider

The guidelines provide the number of weekly servings for each food group. For example, if you have type O blood, the diet suggests eating 4-6 ounces (oz) of lean red meat per week for people assigned male at birth and 2-5 oz for people assigned female at birth and children.

The diet further refines these recommendations based on your ancestral background. If you’re of African descent with type O blood, the diet advises eating 5-7 times the standard weekly recommendation for lean red meat. If you’re of Asian descent with type O blood, the diet recommends consuming 3-5 times the standard weekly amount. 

The blood type diet also recommends avoiding drinking beverages during meals. Instead, it advises consuming liquids at least 30 minutes before eating and waiting at least two hours after a meal before drinking again. That can help prevent weakening digestive enzymes, making food easier to digest.

D’Adamo recommends making changes slowly. You might gradually reduce foods that your blood type should avoid and slowly increase foods that are highly beneficial for you.

Diet Types

The blood type diet has different eating plans for people with blood types O, A, B, and AB to match their genetics. Here’s what each diet recommends:

• Type O diet: Emphasizes high-protein foods and limits grains, beans, and dairy. It’s based on the idea that people with Type O have a digestive system best suited for processing animal proteins, similar to their hunter-gatherer ancestors.
• Type A diet: Focuses on vegetables, fruits, and grains while minimizing meat and dairy. It’s based on the belief that Type A individuals have sensitive immune systems and do best on a vegetarian-like diet, like their agrarian ancestors.
• Type B diet: Includes a balance of meats, vegetables, fruits, grains, and dairy. It’s based on the idea that Type B individuals have a robust digestive system and can eat a variety of foods, as their nomadic ancestors had a diverse diet.
• Type AB diet: Involves a combination of foods from the type A and type B diets. The AB diet is based on the belief that people with type AB blood can benefit from both type A and type B diets, as their blood is a mix of both blood types.

What To Eat and Avoid on the Blood Type Diet

Before starting any diet, it’s best to consult with your healthcare provider to ensure the foods that are recommended for your blood type are safe for you. If you’re interested in following the blood type diet, the lists below offer dietary guidelines with foods that are either highly beneficial, considered neutral, or should be avoided:

Type O Diet

• Highly beneficial foods: Beef, lamb, red snapper, broccoli, collard greens, bananas, mangoes, olive oil, walnuts, and black-eyed peas
• Neutral foods: Chicken, shrimp, brussels sprouts, eggplants, apples, lemons, chicken eggs, sesame oil, almonds, and pecans
• Foods to avoid: Bacon, pork, octopus, cauliflower, cucumbers, kiwis, oranges, cheese, avocado oil, peanuts, cashews, and corn

Type A Diet

• Highly beneficial foods: Red snapper, salmon, olive oil, flaxseed bread, peanuts, pumpkin seeds, black-eyed peas, broccoli, carrots, and blackberries
• Neutral foods: Chicken, turkey, sea bass, barley, beets, cucumbers, apples, eggs, and almonds
• Foods to avoid: Beef, anchovies, conch, blue cheese, butter, coconut oil, pistachios, lima beans, kidney beans, cabbage, potatoes, bananas, and mangoes

Type B Diet

• Highly beneficial foods: Goat, lamb, cod, grouper, cottage cheese, olive oil, walnuts, kidney bean, rice flour, beets, broccoli, and bananas
• Neutral foods: Beef, turkey, herring, brie cheese, almond oil, flaxseed, soybeans, brown rice, celery, and apples
• Foods to avoid: Chicken, lobster, American cheese, avocado oil, cashews, lentils, whole wheat bread, tomatoes, and avocados

Type AB Diet

• Highly beneficial foods: Turkey, cod, grouper, goat cheese, olive oil, peanuts, brown rice, cucumbers, broccoli, and kiwis
• Neutral foods: Goat, lamb, mussels, eggs, almond oil, cashews, green beans, barley, asparagus, apples, and apricots
• Type AB foods to avoid: Bacon, halibut, conch, blue cheese, coconut oil, sesame seeds, lima beans, shiitake mushrooms, avocados, and bananas

Beverages To Drink and Avoid on the Blood Type Diet

The blood type diet also provides guidelines for beverages based on your blood type. Consider the following suggestions for drinks and flavors:

Blood Type	Recommended	Not Recommended
Type O	Black cherry, guava, and mango juices	Blackberry juice, coconut milk, and tangerine juice
Type A	Alkaline fruit juices like diluted black cherry juice concentrate	Orange, papaya, tangerine, or tomato juices and beer
Type B	Cranberry, pineapple, and papaya juices	Coconut milk and pomegranate or tomato juices
Type AB	Chamomile tea, cherry juice, and water with lemon	Guava, mango, and orange juices

Meal Ideas

Starting a new diet can be challenging. But having some meal options in your back pocket can help you better adjust to a new eating plan. Consider the following meal options for each blood type:

Type O Meals

• Breakfast: Essene bread with sweet butter, poached eggs, pineapple juice, and green tea
• Lunch: Sliced chicken breast and salad greens, two plums, and water or seltzer
• Snack: Pumpkin seeds and walnuts with water or seltzer
• Dinner: Baked fish, string bean salad, steamed collard greens, and green or herbal tea

Type A Meals

• Breakfast: Oatmeal with soy milk and maple syrup, grapefruit juice, and coffee or herbal tea
• Lunch: Greek salad, one apple, sprouted wheat bread, and herbal tea
• Snack: Rice cakes with peanut butter, two plums, and green tea or water
• Dinner: Turkey-tofu meatballs, zucchini, string beans, low-fat frozen yogurt, and herbal tea

Type B Meals

• Breakfast: Rice bran cereal with banana and skim milk with grape juice or coffee on the side
• Lunch: Spinach salad, water-packed tuna with mayonnaise, rice cakes, and herbal tea
• Snack: Fruit-juice sweetened yogurt and herbal tea
• Dinner: Broiled fish, steamed vegetables, roasted yams, and fresh fruits with herbal tea or coffee

Type AB Meals

• Breakfast: Diluted grapefruit juice, one poached egg, essene bread with organic almond butter, and coffee
• Lunch: Sliced turkey breast, rye bread, Caesar salad, and two plums with herbal tea
• Snack: Fruit juices
• Dinner: Broiled salmon, brown rice, and spinach salad

Potential Benefits of the Blood Type Diet

Some followers of the blood type diet have reported many health benefits. However, there’s no scientific proof that your blood type influences how your body reacts to different foods. So before you start this diet, it’s best to weigh the benefits and risks of the blood type diet theory.

May Help With Weight Loss

D’Adamo claims you can lose weight by eating based on your blood type. However, weight loss likely occurs because the diet encourages the consumption of whole, unprocessed foods like fruits, vegetables, and lean meats, which are generally healthy choices. 

By avoiding ultra-processed foods, which are often high in calories, you may naturally reduce your calorie intake and lose weight. Additionally, the blood type diet promotes regular exercise, which, when combined with a healthy diet, can help you lose weight.

Can Improve Heart Health

Testimonials about the blood type diet include better heart health. However, these changes are likely due to the healthier eating patterns encouraged by the diet and unrelated to their blood type.

Because the blood type diet boasts eating nutritious foods that include whole grains, fruits, and vegetables, your heart health may improve based on healthier food choices rather than specific foods you eat based on your blood type. 

Is the Blood Type Diet Safe?

The blood type diet promotes eating whole, unprocessed foods, which is generally a healthy approach. However, it also has some potential downsides and risks. 

One of the main issues is that this diet recommends avoiding certain foods unnecessarily, which could result in nutrient deficiencies. Furthermore, the recommended meal plan for some blood types may not align with the USDA’s guidelines for a balanced and healthy diet.

For example, the Type O diet restricts dairy and grains, which are usually considered part of a balanced diet. This could also make it challenging to get enough calcium, which is important for your bones and muscles. 

The health benefits claimed by the blood type diet are based on theory and not proven by scientific research. It’s best to talk to your healthcare provider or a registered dietitian before starting this diet, especially if you have a medical condition or are pregnant or breastfeeding. They can create a personalized nutrition plan that evaluates your health needs, preferences, and lifestyle. A personalized approach is more likely to be sustainable, effective, and fit your health goals.

Drawbacks

The blood type diet limits food choices, which can make it difficult to enjoy certain meals or dine out. This restrictive approach can make the diet challenging to follow and maintain in the long term.

Additionally, the diet may not suit all lifestyles. For example, the Type O diet emphasizes meat consumption, which can be problematic if you don’t eat meat and your blood type is O. This diet also suggests eating organic and specialty foods, which can be expensive.

A Quick Review

The blood type diet, created by Dr. Peter D’Adamo, suggests that your blood type should determine your food choices for optimal health and weight management. The diet is based on the idea that different blood types respond differently to certain foods.

While some people have noticed some benefits anecdotally, the blood type diet doesn’t have enough scientific evidence to determine its effectiveness. If you’re interested in the blood type diet, however, it’s best to consult with your healthcare provider to learn if the guidelines of the blood type diet are safe for you to follow.

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