The AB positive blood type diet is the most varied of the four blood type diet protocols, combining elements from both Type A and Type B guidelines. It emphasizes tofu, seafood, dairy, and green vegetables while restricting red meat, corn, wheat, and certain legumes.
Blood type AB is the rarest ABO blood group, found in fewer than 5% of the global population. D’Adamo describes Type AB as inheriting the tolerances and predispositions of both Type A and Type B, giving it the broadest dietary range but also specific sensitivities. The protocol targets immunity, metabolism management, and stress response regulation. For weight loss, D’Adamo specifically recommends vegetables, pineapple, olive oil, and soy as beneficial, while dairy, wheat, corn, and kidney beans are flagged as weight-promoting foods for this group.
This guide covers what AB positive individuals are advised to eat, what to avoid, what the research shows about the diet’s validity, and how to build a practical, sustainable eating plan informed by the framework.
What Is the AB Positive Blood Type Diet?
The AB positive blood type diet is a hybrid eating protocol combining selected elements from both the Type A and Type B dietary frameworks. It emphasizes tofu, seafood, dairy products, and green vegetables as core food categories. Peter D’Adamo designed it to address the unique physiological traits he attributes to individuals with AB blood, including low stomach acid and a mixed immune profile inherited from both A and B ancestral lineages.
Here’s the core framing. D’Adamo describes Type AB as the most recently evolved blood type, produced through the intermingling of Type A and Type B populations rather than through environmental adaptation. This mixed origin is why Type AB carries both the sensitivities of Type A and the broader food tolerance of Type B. The dietary protocol attempts to balance both sets of characteristics in a single eating plan.
The AB diet is designed to do three things: boost immunity, manage metabolism, and counter stress-related adrenaline overproduction that D’Adamo claims is common in Type AB individuals. Moderate physical activity with a mind-body component, such as cycling, swimming, or yoga, is paired with the dietary protocol as the recommended exercise approach for this blood type.
What Makes Blood Type AB Unique Among Blood Groups?
Blood type AB is the rarest ABO blood group, present in fewer than 5% of the global population. AB positive individuals are universal plasma donors, able to donate plasma to any blood type. From a medical standpoint, AB blood carries both A and B antigens on red blood cells and no anti-A or anti-B antibodies in plasma. These characteristics make AB the newest and most complex of the four blood groups.
D’Adamo claims Type AB individuals have a unique immune advantage: the presence of both A and B antigens gives the immune system broader recognition capabilities than either single-antigen type. The tradeoff, in his framework, is a higher susceptibility to certain diseases and a digestive system with lower stomach acid production than Types O and B.
Low stomach acid is the most clinically significant dietary claim D’Adamo makes for Type AB. He argues this limits the group’s ability to efficiently digest large portions of animal protein. The recommendation to limit red meat and favor smaller protein portions with digestive support foods such as soy and tofu flows directly from this claim. The low-acid premise is not validated by blood-type-specific gastric acid research.
What Can AB Positive Blood Type People Eat?
Approved foods for blood type AB include seafood, tofu, dairy products, green vegetables, legumes, and certain grains. The food list is more varied than Type O and more inclusive of animal products than Type A. The AB protocol permits dairy in quantities that Type A restricts, while limiting red meat in ways that Type O permits freely.
AB Blood Type Approved Foods by Category:
| Category | Beneficial | Neutral (permitted) |
| Seafood | Sardines, tuna, cod, red snapper, mackerel | Salmon, trout, shrimp, clams |
| Dairy | Yogurt, kefir, low-fat milk, mozzarella, ricotta | Most mild cheeses, eggs |
| Protein (plant) | Tofu, tempeh, peanuts, walnuts, lentils | Almonds, brazil nuts, cashews |
| Grains | Rice, rye, oats, spelt | Corn-free bread, millet, quinoa |
| Vegetables | Broccoli, kale, beets, celery, cucumber | Asparagus, cauliflower, spinach, tomatoes |
| Fruits | Grapes, plums, figs, pineapple, cherries | Apples, blueberries, melon, peaches |
Tofu and soy products are highlighted as particularly beneficial for Type AB weight management. D’Adamo specifically identifies soy, vegetables, pineapple, and olive oil as the top weight-loss foods for this blood group. These foods are emphasized not just as dietary staples but as active tools for managing the weight gain tendencies he attributes to the AB metabolism.
Which Proteins Are Best for Blood Type AB?
Seafood is the top animal protein recommendation for blood type AB. Sardines, tuna, cod, red snapper, and mackerel are all designated as highly beneficial. These choices provide complete protein, omega-3 fatty acids, and are easier to digest than red meat, which D’Adamo links to the low stomach acid he claims characterizes Type AB digestion.
Tofu and tempeh are the primary plant protein sources encouraged in the AB protocol. D’Adamo positions soy-based proteins as metabolically advantageous for Type AB, claiming they support efficient protein utilization without the digestive burden of animal muscle meat. Peanuts and walnuts also appear in the beneficial tier as supplementary plant protein sources.
Small portions of turkey and lamb are listed as neutral for Type AB. Red meat such as beef and pork is in the avoid category, though moderate amounts of lamb are permitted as a transitional protein. D’Adamo advises keeping all animal protein portions small for Type AB, recommending 55-85 grams (2-3 oz) per serving due to the purported low stomach acid profile of this blood group.
What Vegetables and Fruits Work for Blood Type AB?
Dark green vegetables are among the most beneficial food categories for blood type AB in D’Adamo’s system. Broccoli, kale, beets, celery, and cucumber appear in the highly beneficial tier. These vegetables provide fiber, iron, calcium, and antioxidants that support the immune and metabolic functions D’Adamo prioritizes for this blood group.
Pineapple deserves specific mention as a beneficial fruit for Type AB weight management. D’Adamo identifies bromelain, the enzyme concentrated in pineapple, as particularly supportive of digestion and metabolism for Type AB individuals. Grapes, plums, figs, and cherries also fall in the beneficial fruit category. Oranges and bananas are listed as neutral for most AB individuals.
Some otherwise common vegetables are designated as avoids for Type AB. Corn, avocado, and artichokes appear on the Type AB avoid list. Peppers are also flagged. Raw and cooked vegetables both appear in the approved lists, with cooking method generally left to individual preference. Olive oil is specifically recommended as the cooking oil of choice for Type AB across all meal contexts.
What Foods Should Blood Type AB Avoid?
The Type AB avoid list centers on red meat, corn, wheat, kidney beans, buckwheat, caffeine, alcohol, and smoked or cured meats. D’Adamo claims each category creates specific metabolic or immune problems for Type AB individuals based on lectin interactions or stomach acid dynamics. The avoid list is less restrictive than Type O but more targeted than Type B.
Key Foods to Avoid on the AB Blood Type Diet:
- Red meat (beef, pork, venison) — difficult to digest due to low stomach acid
- Corn and corn derivatives
- Wheat and wheat-based products in excess
- Kidney beans, lima beans, and buckwheat
- Caffeine — worsens stress-related adrenaline overproduction
- Alcohol — recommended to avoid or minimize
- Smoked and cured meats (ham, bacon, salami)
- Tropical fruits: mangoes, guava, papaya
Caffeine avoidance is particularly emphasized for Type AB. D’Adamo claims Type AB individuals have a tendency toward overproduction of adrenaline under stress, and caffeine amplifies this stress response. He recommends herbal teas, particularly chamomile and green tea in moderation, as replacements. This recommendation is framed as supporting both digestive function and stress resilience in the AB system.
Are Red Meat and Certain Beans Off-Limits for Blood Type AB?
Red meat is listed as an avoid for Type AB primarily because of the low stomach acid claim. D’Adamo argues that Type AB individuals lack the gastric acid needed to efficiently break down large amounts of animal muscle protein. Beef, pork, and game meats are designated as avoids on this basis. Small amounts of lamb are the exception, listed as neutral rather than an avoid.
Kidney beans and lima beans are flagged as particularly problematic for Type AB. D’Adamo claims specific lectins in these legumes interfere with insulin production in Type AB, contributing to hypoglycemia and weight gain. Lentils, by contrast, appear in the beneficial tier, illustrating that the avoid designations are lectin-specific rather than a blanket legume restriction.
Buckwheat is another notable avoid for Type AB that surprises followers familiar with its health reputation. D’Adamo places it on the avoid list based on the claim that its lectins cause hypoglycemia in Type AB specifically. This reflects the highly specific nature of the blood type diet’s food designations, where a single food can be beneficial for one blood type and harmful for another within the same framework.
Does the AB Positive Blood Type Diet Actually Work?
The AB positive blood type diet has not been confirmed as more effective than other dietary approaches in any independent peer-reviewed study. Research consistently shows that the benefits reported by Type AB diet followers reflect general dietary improvements, not blood type compatibility. The structured elimination of processed foods, refined carbohydrates, and red meat drives any measurable outcome.
And here is the kicker. Many of the foods the AB protocol emphasizes, including seafood, tofu, fermented dairy, and dark leafy greens, are independently recognized as health-promoting by mainstream nutrition research. The benefit a Type AB diet follower experiences is real. The explanation that blood type is driving those benefits is not supported by clinical evidence.
The behavioral component also matters significantly. Type AB diet followers report stronger dietary consistency because the blood type framework provides a clear identity and rule system. Structured eating with defined allowed and avoided categories reduces impulsive food choices and improves meal planning behavior. These are behavioral effects that operate independently of any blood type mechanism.
What Does Science Say About Type AB Diet Claims?
The 2013 University of Toronto PLOS ONE study remains the most comprehensive test of the blood type diet hypothesis to date. Among 1,455 participants, the Type AB diet (tofu-focused, plant-forward, low red meat) improved cardiometabolic markers. Blood type did not modify outcomes. Non-AB participants following the AB dietary pattern showed identical improvements to actual Type AB individuals.
The low stomach acid claim central to the AB protocol has not been validated by blood-type-specific gastric secretion research. Gastric acid production varies between individuals based on age, medication use, stress, and health conditions. No study has confirmed that ABO blood type is a reliable predictor of gastric acid output in a way that should guide dietary protein choices.
Researchers at the British Dietetic Association, Harvard Health, and the Cleveland Clinic all advise that blood type is not a scientifically supported basis for dietary decisions. The AB diet’s emphasis on seafood, tofu, fermented dairy, and vegetables aligns closely with Mediterranean and plant-forward dietary patterns, both of which have extensive independent evidence supporting their benefits across all blood types.
What Are the Benefits and Risks of the AB Blood Type Diet?
The primary benefit of the AB blood type diet is its whole-food emphasis, which naturally reduces processed food intake and increases nutrient density in most followers’ diets. The protocol’s focus on seafood, tofu, fermented dairy, and dark greens represents a nutritionally strong dietary foundation by mainstream standards, regardless of whether the blood type mechanism is valid.
The risks are meaningful but less severe than with Type O. The AB protocol is less restrictive than Type O’s broad grain and dairy exclusions. However, the caffeine and red meat restrictions can feel socially and practically limiting. The lectin-based rationale for avoid foods lacks scientific grounding, meaning followers may be restricting nutritious foods based on unsupported claims.
The most legitimate concern is the dietary framework’s reliance on unvalidated science. Followers who invest deeply in the blood type model may reject evidence-based dietary changes that conflict with their blood type designation, even when those changes are nutritionally beneficial. The framework can become a barrier to good nutritional decision-making if applied rigidly without professional guidance.
Can the AB Blood Type Diet Help With Weight Loss?
Yes, but not because of blood type compatibility. The AB protocol produces weight loss through caloric displacement: replacing red meat, processed foods, and refined grains with tofu, seafood, and vegetables reduces overall caloric density. This shift creates a natural caloric reduction that drives fat loss in most followers, regardless of ABO blood group.
D’Adamo specifically identifies soy, vegetables, pineapple, and olive oil as the top Type AB weight loss foods. Each of these choices is independently associated with satiety, metabolic support, or reduced inflammatory load in mainstream nutrition research. The weight loss benefit from including these foods is real. The blood type explanation for why they work is not supported by evidence.
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How Should Blood Type AB Start the Diet?
The practical starting point for the AB blood type diet is adding the beneficial foods before removing the avoid foods. Increasing tofu, seafood, fermented dairy, and dark leafy greens in daily meals builds the foundation of the protocol without the disruption of simultaneous elimination. This approach improves early adherence and reduces the nutritional risk of abrupt restriction.
Confirm blood type before committing to the AB protocol. Blood type can be confirmed through a primary care physician, blood bank donation, or at-home testing kit. The distinction between AB positive and AB negative has no dietary implications in D’Adamo’s framework. Both follow the same AB dietary guidelines. The Rh factor (positive or negative) is relevant to medical contexts but not to blood type diet food selection.
Introduce avoids gradually over 2-4 weeks. Begin by reducing red meat and replacing it with seafood and tofu. Then reduce caffeine intake by substituting herbal teas. Processed and smoked meats come next. This graduated approach prevents the shock of sudden dietary restriction, allows time to identify satisfying replacements, and makes the behavioral shift more sustainable for long-term compliance.
AB Blood Type Diet Starting Steps:
- Confirm blood type through a physician, blood bank, or at-home kit
- Review the full beneficial, neutral, and avoid food lists for Type AB
- Add tofu, sardines, kefir, and dark leafy greens as daily staples
- Gradually reduce red meat, replacing portions with seafood or tofu
- Reduce caffeine over 1-2 weeks; replace with green tea or herbal tea
- Consult a registered dietitian to review nutritional completeness before full implementation
What Supplements Are Recommended for Blood Type AB?
D’Adamo recommends specific supplements for Type AB to address the low stomach acid and immune vulnerabilities he attributes to this blood group. His protocol includes digestive enzymes to support protein breakdown, hawthorn berry for cardiovascular support, and echinacea or zinc for immune function. These are framed as compensating for the physiological traits purportedly linked to Type AB blood.
Vitamin C supplementation is recommended for Type AB individuals in D’Adamo’s system, based on the claim that this blood type is more susceptible to certain immune challenges. Quercetin, found naturally in onions, apples, and berries, is also recommended for its purported anti-inflammatory properties relevant to the AB immune profile.
No clinical evidence confirms that Type AB individuals have systematically different supplementation needs from other blood types. Standard supplementation guidance, including vitamin D, omega-3 fatty acids, and a general multivitamin, applies equally across blood types according to mainstream nutritional medicine. A registered dietitian or physician can assess actual deficiency risk through blood panels before any supplementation protocol is implemented.
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