A Closer Look at the Blood Type AB Diet Theory
The idea that your blood type—O, A, B, or AB—should dictate your diet was popularized by naturopathic physician Peter J. D'Adamo. In his book Eat Right 4 Your Type, he proposes that each blood type has unique evolutionary characteristics that affect digestion and overall health, and consuming specific foods can optimize well-being. While the diet has gained a following, the scientific community has consistently found no evidence to support its claims, with a 2014 review of 1,415 studies finding no proof of its benefits. Despite the lack of scientific backing, the diet's specific food lists remain a point of curiosity.
For blood group AB, which D'Adamo refers to as the 'enigma' and a mix of A and B traits, the recommendations can be complex. The theory suggests AB individuals have low stomach acid, similar to type A, making it difficult to metabolize red meat efficiently. This, combined with the B type's sensitivity to certain lectins (a protein found in some plants), leads to a unique set of dietary guidelines.
Foods the Blood Type AB Diet Suggests Avoiding
Based on D'Adamo's theory, the following categories and examples of foods are believed to be harmful or poorly digested by people with blood type AB.
Meat and Poultry
Due to the theorized low stomach acid, the digestion of certain meats is supposedly less efficient. The diet suggests that AB individuals should limit their meat consumption and avoid specific types to prevent potential weight gain and other issues.
- Processed and Cured Meats: Bacon, ham, and other processed meats are on the exclusion list.
- Chicken and Pork: The diet suggests that chicken can be problematic for those with the B blood type component, and pork is generally avoided.
- Certain Seafood: White fish and halibut are often listed as being less beneficial.
Dairy Products
While some dairy like yogurt is considered beneficial, others are flagged for potential issues related to lectins and digestion.
- Whole Milk and Blue Cheese: These are mentioned as foods to limit or avoid.
Grains, Legumes, and Nuts
Certain plant-based foods, especially those high in lectins that can interact with blood antigens, are part of the avoidance list.
- Corn and Buckwheat: Both are prominently featured as foods to avoid for AB blood types.
- Legumes: Lima beans and kidney beans are often listed as detrimental.
- Sesame and Pumpkin Seeds: These are also included in the list of items to be wary of.
Fruits, Vegetables, and Oils
While most fruits and vegetables are encouraged, a few are singled out for their potential negative effects.
- Bananas and Mangoes: Both are considered less beneficial for this blood type.
- Avocados: This fruit, though generally healthy, is on some avoidance lists related to the diet.
- Coconut Oil: The diet specifically lists coconut oil as an item to avoid.
Beverages and Condiments
Beyond solid foods, the diet also offers specific guidance on what AB individuals should drink.
- Caffeine and Alcohol: Both are generally discouraged for AB blood types.
- Black Tea: Also a recommended avoidance.
Blood Type AB Diet: Recommended vs. Avoided Foods (Based on Theory)
| Food Category | Recommended Foods | Avoided Foods |
|---|---|---|
| Protein | Tofu, seafood (cod, grouper, sardines), goat, lamb | Bacon, ham, pork, chicken, white fish, halibut |
| Dairy | Yogurt, goat cheese, eggs, soy milk | Whole milk, blue cheese |
| Grains | Oats, rye, brown rice, millets | Corn, buckwheat |
| Legumes/Nuts | Peanuts, lentils (specific), walnuts | Kidney beans, lima beans, sesame seeds, pumpkin seeds |
| Fruits/Veggies | Berries, plums, grapes, broccoli, cucumber, garlic | Bananas, mangoes, oranges, coconuts, avocados |
| Fats | Olive oil, almond oil | Coconut oil |
| Beverages | Herbal teas, water with lemon | Caffeine, alcohol, black tea |
The Crucial Scientific Context: Is the Blood Type Diet Valid?
While the blood type diet provides a detailed set of rules, it's vital to address the scientific perspective. Reputable health organizations and nutrition experts widely regard the diet as lacking a scientific basis.
- Absence of Scientific Evidence: Multiple reviews of existing literature, including a comprehensive review in the American Journal of Clinical Nutrition, found no evidence to prove that the blood type diet works or provides health benefits based on blood type.
- Potential for Health Improvement is Incidental: Any health improvements reported by followers are likely due to the diet's general promotion of eating whole, unprocessed foods and reducing unhealthy options like processed meats and excessive caffeine. These improvements would occur regardless of an individual's blood type.
- Risk of Nutrient Deficiency: Following a highly restrictive diet without proper planning and a strong rationale can lead to nutrient deficiencies. Avoiding whole food groups unnecessarily, like some of the items on the AB avoidance list, can limit essential vitamins and minerals.
- Consensus from Experts: Leading registered dietitian nutritionists and major health institutions assert that there is no scientific basis for eating according to one's blood type.
Focusing on a Scientifically-Backed Approach
Instead of focusing on restrictive rules based on an unproven theory, AB individuals—like everyone else—are better served by adopting universally accepted healthy eating practices. This includes a balanced diet rich in whole foods, such as fruits, vegetables, lean proteins, and whole grains.
- Prioritize Nutrient-Dense Foods: A varied diet that includes plenty of vegetables, fruits, and quality protein sources provides the best possible nutrition.
- Limit Processed Items: Reducing processed meats, sugary drinks, and high-fat foods is a sound recommendation for everyone, regardless of blood type.
- Consult a Professional: For personalized advice, particularly if you have underlying health conditions, speaking with a registered dietitian is always the best course of action. They can provide guidance based on proven nutritional science, genetics, and lifestyle, not blood group.
Conclusion
When considering what foods should blood group AB avoid, it is important to distinguish between popular theory and scientific fact. While the D'Adamo diet offers specific recommendations, extensive research has found no credible evidence linking blood type to optimal dietary needs. The potential health benefits some people experience are more likely a result of shifting towards a healthier, less-processed diet, which benefits everyone. For long-term health, a balanced and varied diet, informed by evidence-based nutrition and tailored to individual needs, is a far more reliable approach than following blood type-based restrictions.
For more information on the scientific consensus, you can read the critical analysis published in PLOS One.
