The concept of tailoring one's diet to their blood type was popularized by naturopath Peter D'Adamo. His theory posits that blood type, inherited from our ancestors, determines which foods we should eat to be healthy. The Rh factor (positive or negative) does not significantly change the core dietary recommendations for the ABO blood type. For individuals with B negative blood, the guidance follows the general advice for all B blood types, framing them as "nomads" who thrive on a varied, omnivorous diet.
Recommended Foods for the B Blood Type Diet
Followers of the blood type diet are encouraged to consume a wide variety of foods from different groups, with a special emphasis on certain items believed to be highly beneficial.
Meats & Poultry
- Beneficial: Lamb, mutton, rabbit, venison, cod, salmon, and other deep-ocean fish. Turkey is considered neutral and acceptable.
- Rationale: These protein sources are said to support the metabolism of B types.
Dairy & Eggs
- Beneficial: B blood types are unique in the blood type diet for their ability to generally tolerate and benefit from dairy. Options include goat milk, kefir, feta, mozzarella, and yogurt.
- Rationale: Ancestrally, B types are thought to have developed tolerance for dairy from nomadic herding cultures.
Vegetables
- Beneficial: A wide array of vegetables is recommended, particularly leafy greens such as broccoli, kale, spinach, cabbage, beets, and carrots.
- Rationale: These are highly nutritious and believed to support overall health.
Fruits
- Beneficial: Fruits considered beneficial include bananas, cranberries, grapes, papaya, and pineapple.
- Rationale: These fruits provide vitamins and antioxidants that are said to be well-metabolized by B types.
Grains & Flours
- Beneficial: Some grains and flours are acceptable, such as millet, rice, oatmeal, oat bran, and spelt.
- Rationale: These are tolerated better than wheat, according to the theory.
Oils
- Beneficial: Olive oil is considered the best oil for B types.
- Rationale: It is believed to have a positive metabolic effect.
Foods to Avoid with the B Blood Type Diet
Certain foods are identified as problematic for B types, potentially causing inflammation or other negative health effects due to incompatible lectins.
- Poultry: Chicken is specifically recommended to be avoided by D'Adamo, who claims it can lead to immune issues.
- Grains: Wheat, corn, and buckwheat are considered harmful and are to be eliminated.
- Legumes: Lentils, peanuts, and many types of beans (like pinto and black beans) are discouraged.
- Nuts & Seeds: Peanuts, sesame seeds, sunflower seeds, and their butters are listed as foods to avoid.
- Vegetables: While most are good, tomatoes are notably on the avoidance list for type B.
- Seafood: Shellfish like shrimp, lobster, and crab are best avoided.
Blood Type Diet: A Comparison
| Food Category | Recommended for B Types | Avoid for B Types |
|---|---|---|
| Meats | Lamb, Mutton, Venison, Rabbit | Chicken, Pork, Bacon |
| Seafood | Cod, Salmon, Halibut, Sardines | Shrimp, Lobster, Shellfish |
| Dairy | Yogurt, Kefir, Goat Cheese, Feta | Blue Cheese, American Cheese, Ice Cream |
| Grains | Millet, Oatmeal, Rice | Wheat, Corn, Buckwheat, Rye |
| Legumes | Navy, Lima, Kidney Beans | Lentils, Peanuts, Black-eyed Peas |
| Vegetables | Broccoli, Kale, Spinach, Cabbage | Tomatoes, Avocado, Pumpkin |
| Oils | Olive oil | Canola oil, Corn oil, Peanut oil |
Is the Blood Type Diet Medically Proven?
Despite the detailed food lists and underlying theory, a significant body of scientific research does not support the efficacy of the blood type diet. Health improvements reported by some followers are more likely the result of adopting healthier general eating habits, such as reducing processed foods, rather than a specific interaction with their blood type.
A systematic review published in the American Journal of Clinical Nutrition found no evidence to validate the purported health benefits of blood type diets, and recommended that claims need to be scientifically tested. Furthermore, critics point out that the diet is often restrictive, can be expensive due to specific food recommendations, and does not account for individual preferences, allergies, or other health conditions. For a more detailed review of the scientific literature on the blood type diet, see the abstract of the systematic review on PubMed.
General Healthy Eating Principles for B Negative Individuals
Instead of relying on an unproven blood type diet, B negative individuals, like everyone else, should focus on a well-rounded and balanced diet based on established nutritional guidelines. This means prioritizing nutrient-dense whole foods and limiting processed items.
- Lean Protein: Include lean meats, fish, poultry, and plant-based protein sources like legumes.
- Fiber-Rich Foods: Incorporate plenty of fruits, vegetables, and whole grains for digestive health.
- Healthy Fats: Choose healthy fats from sources like olive oil, nuts, and seeds.
- Dairy (if tolerated): Include dairy or dairy alternatives for calcium and protein.
- Hydration: Drink plenty of water throughout the day.
- Consult a Professional: A registered dietitian can provide personalized advice based on your medical history, lifestyle, and dietary needs, rather than a pseudoscience theory.
Conclusion
While the blood type diet provides specific guidelines for what a person with B negative blood type should eat, it is not backed by scientific evidence and is considered a fad by most health experts. The theory's claimed benefits likely stem from its emphasis on healthy, whole foods and avoidance of processed items, which are sound nutritional practices for everyone. For optimal health, B negative individuals should focus on a balanced, varied diet of lean proteins, fresh produce, and healthy fats, and consult a healthcare professional for personalized guidance that considers their unique health profile, not just their blood type.
