The concept of tailoring one's diet to their blood type was popularized by naturopathic doctor Peter J. D'Adamo in his 1996 book, Eat Right 4 Your Type. The theory suggests that blood type, determined by the ABO system, influences how the body processes food due to proteins called lectins. Adherents to the diet believe that consuming foods with incompatible lectins can cause health issues, though mainstream science has widely debunked this claim. For individuals with A+ blood, the diet recommends a primarily vegetarian approach, citing an ancestral history of agrarian lifestyles and lower levels of stomach acid.
The Controversial Foods to Avoid on the A+ Blood Type Diet
While science does not endorse these specific restrictions, here is a breakdown of the foods the A+ blood type diet suggests followers avoid:
Meats and Poultry The A+ diet is largely plant-based, and as a result, red meat and most poultry are on the 'avoid' list. The theory posits that individuals with type A blood have a more difficult time digesting these animal proteins due to supposedly lower stomach acid levels.
- Beef
- Pork
- Lamb
- Veal
- Venison
- Duck and goose
Dairy Products Dairy is generally discouraged for type A individuals on this diet, with some exceptions. The claim is that many dairy products can be difficult to digest and may cause issues.
- Cow's milk
- Butter
- Most cheeses (e.g., blue cheese, cream cheese)
- Ice cream
- Yogurt (some specific types are allowed in moderation)
Seafood While some fish like salmon and mackerel are considered beneficial, the diet lists a wide array of seafood that should be avoided. These include many shellfish and bottom-feeding fish.
- Anchovy
- Barracuda
- Catfish
- Clam
- Crab
- Eel
- Flounder
- Halibut
- Lobster
- Shrimp
- Mussels
- Octopus
Beans and Legumes Although many beans and legumes are encouraged, certain varieties are singled out as incompatible.
- Kidney beans
- Lima beans
- Garbanzo beans (chickpeas)
- Navy beans
Grains and Baked Goods For type A, the diet promotes whole grains but restricts certain wheat products and heavily processed grains.
- White flour and white bread
- Durum wheat
- Wheat bran
- Cream of wheat
- Semolina pasta
Fruits and Vegetables Even with a vegetarian focus, some fruits and vegetables are considered 'unfavorable' in the A+ diet.
- Cabbage
- Eggplant
- Potatoes
- Tomatoes
- Bananas
- Oranges
- Cantaloupe
- Mangoes
- Papayas
Nuts and Fats Certain nuts and specific oils are also on the list of foods to avoid.
- Pistachios
- Cashews
- Brazil nuts
- Corn oil
- Peanut oil
- Sesame oil
Scientific Consensus vs. Blood Type Theory
It is essential to understand that the foundation of the blood type diet lacks scientific backing. Multiple studies and reviews have found no connection between a person's blood type and their dietary needs or health outcomes. Any perceived benefits, such as weight loss or improved health markers, are likely the result of the diet's tendency to eliminate processed and unhealthy foods, which is a universally beneficial practice. The diet's restrictive nature, particularly in eliminating certain dairy products and red meat, can lead to calorie reduction and an increased intake of fruits and vegetables, mirroring the effects of any healthy, balanced eating plan.
Blood Type Diet Claims vs. Standard Nutritional Advice
| Feature | Blood Type Diet Rationale | Standard Nutritional Science Perspective |
|---|---|---|
| Dietary basis | Based on evolutionary history tied to blood type and incompatible lectins. | Based on an individual's caloric needs, nutrient requirements, and medical history. |
| A+ protein sources | Plant-based proteins like tofu and legumes are prioritized; red meat and most poultry are excluded due to supposed digestive issues. | Protein sources should be varied and balanced, including lean meats, poultry, fish, beans, and nuts. |
| Key restrictions | Recommends avoiding red meat, specific dairy, and certain vegetables and grains. | Focuses on limiting highly processed foods, excess sugars, and unhealthy fats for overall health. |
| Scientific support | Largely unsupported by clinical research, considered a fad diet by many experts. | Supported by extensive research on balanced nutrition, macronutrients, and micronutrients. |
| Potential benefits | Claims to improve digestion, boost energy, and aid weight loss specifically for A+ individuals. | Any benefits observed (e.g., weight loss) are likely due to general healthy eating practices encouraged by the diet's restrictions, not blood type. |
Conclusion
While the concept of a diet tailored to your blood type is intriguing, the scientific evidence to support it simply does not exist. Instead of focusing on what foods should A+ people avoid based on a disproven theory, individuals can benefit more by adopting general healthy eating principles. A balanced, varied diet rich in fruits, vegetables, whole grains, and lean proteins is universally recommended by health professionals. Consulting a registered dietitian or doctor is the most reliable way to create a personalized nutrition plan that truly benefits your health without unnecessary and unsupported restrictions.
