The blood type diet, developed by Dr. Peter D'Adamo, is based on the unproven theory that an individual's diet should align with their blood type for optimal health. For those with blood type AB—the rarest and newest blood group—the dietary recommendations are a blend of those for types A and B, featuring a mix of vegetarian foods and moderate animal protein. Proponents claim that due to lower stomach acid levels, similar to blood type A, AB individuals struggle to metabolize meat efficiently, leading to storage as fat. Furthermore, lectins, which are proteins found in certain foods, are said to be incompatible with specific blood types, causing health issues like cell clumping. However, it is crucial to understand that major health organizations and extensive scientific reviews have found no evidence to support these claims, and experts often classify it as a fad diet. Any health benefits experienced are likely due to the general encouragement of whole, unprocessed foods.
Specific Foods to Avoid for AB Blood Type
Based on D'Adamo's recommendations, certain food groups and specific items are classified as harmful or neutral for people with AB blood. These are often linked to the theory of low stomach acid or incompatible lectins.
Harmful Meats and Poultry
- Chicken: Considered an irritant for the AB digestive tract, unlike other poultry.
- Smoked and cured meats: Due to lower stomach acid and higher risk of stomach cancer, these processed meats are best avoided.
- Pork, beef, and veal: These are thought to be poorly digested by AB types.
Incompatible Grains and Starches
- Buckwheat: Believed to contain lectins that are not well-tolerated by AB individuals.
- Corn and corn products: Considered an inflammatory food for AB types.
Problematic Beans, Seeds, and Nuts
- Kidney beans and red beans: These legumes may contain lectins that interfere with AB metabolism.
- Sesame seeds, sunflower seeds, and pumpkin seeds: D'Adamo's diet lists these seeds as ones to avoid for AB types.
Fruits and Vegetables to Limit
- Bananas, oranges, mangos, guavas, and coconuts: These fruits are sometimes listed as foods to avoid, particularly in older iterations of the diet plan.
- Red peppers: While many vegetables are beneficial, red peppers are on some avoidance lists.
Beverages and Other Items
- Caffeine and alcohol (in excess): D'Adamo recommends limiting these items due to their potential impact on AB's sensitive immune system and metabolism.
Comparison of AB Diet Recommendations vs. Standard Nutrition
| Feature | Blood Type AB Diet (D'Adamo) | General Nutritional Guidance (Experts) |
|---|---|---|
| Scientific Basis | Lacks scientific evidence; considered a fad diet. | Supported by extensive research on balanced macronutrients and micronutrients. |
| Dietary Approach | Prescribes specific foods based on blood type and evolutionary theory. | Recommends a balanced intake of all food groups, individualized for health goals. |
| Inclusion of Meat | Advises moderation of some meats, avoidance of others like chicken. | Supports lean meat and poultry as part of a balanced diet for protein. |
| Role of Lectins | Claims lectins are incompatible with certain blood types. | Recognizes lectins, but considers them harmless in most cooked foods. |
| Food Restrictions | Restricts entire healthy food groups like whole grains and specific vegetables. | Emphasizes variety and balance; avoids unnecessary restrictions. |
| Health Benefits | Any health improvements are likely due to reduced processed foods. | Proven to reduce chronic disease risk and improve overall well-being. |
The Scientific Controversy
While the AB blood type diet provides a detailed framework, its core premise has been debunked by the scientific and medical community. A systematic review published in the American Journal of Clinical Nutrition found no evidence to support the claimed benefits of blood type diets. The notion that lectins from specific foods cause health problems based on blood type is largely unsupported. In reality, cooking and digesting most foods denatures or breaks down lectins.
Health experts emphasize that any positive outcomes from following such a diet are likely the result of adopting generally healthier eating habits, such as reducing intake of processed foods, refined sugars, and excess calories, which are common recommendations in most of D'Adamo's plans. The restrictions can be challenging and potentially lead to nutrient deficiencies if not managed properly. A balanced, varied diet remains the cornerstone of good health, regardless of blood type.
Conclusion
While intriguing, the blood type AB diet remains a theory without conclusive scientific evidence to support its claims about avoiding certain foods based on your blood type. The list of foods that an AB blood type should not eat is extensive and includes common items like chicken, corn, and specific legumes and fruits. However, any perceived benefits from this restrictive approach likely stem from eliminating unhealthy processed foods rather than the blood type-specific dietary plan. It is highly recommended to consult a registered dietitian or healthcare provider before making significant changes to your diet to ensure your nutritional needs are met in a safe and effective way. Choosing a balanced, scientifically-backed eating pattern that prioritizes whole foods is a more reliable path to improved health. For more on the controversy, see this blog post from Harvard Health.(https://www.health.harvard.edu/blog/diet-not-working-maybe-its-not-your-type-2017051211678)
