The Blood Type Diet's Theory for A+ Individuals
Naturopathic physician Peter D'Adamo popularized the blood type diet in his 1996 book, Eat Right 4 Your Type. The diet's premise is that people with different blood types have distinct nutritional needs, theorizing that Type A blood evolved when humans began to farm. Consequently, D'Adamo dubbed Type A individuals "The Cultivator" and recommended a largely vegetarian diet, suggesting they avoid foods that were not part of an early agrarian lifestyle. A key component of the theory revolves around proteins called lectins, which D'Adamo claimed can be incompatible with a person's blood type, causing negative health effects.
A List of Foods to "Avoid" for A+ Blood Type (According to the Theory)
Meats and Poultry
According to the blood type diet, Type A individuals have lower stomach acid, making it difficult to digest animal protein efficiently. A vegetarian-based diet is therefore recommended, and most meats are listed as foods to avoid. The most commonly restricted items include:
- Beef
- Pork
- Lamb
- Veal
- Venison
- Duck
- Goose
Certain seafood is also on the list, including anchovies, barracuda, caviar, clams, crab, herring, lobster, and shrimp. Some sources suggest white-meat fish should also be limited.
Dairy Products
Following the theory, dairy products are generally not well-tolerated by those with Type A blood. Foods to avoid include:
- Cow's milk
- Certain cheeses like American, Blue, and Provolone
- Ice cream
Some cultured dairy products like yogurt and kefir, along with goat cheese and mozzarella, are sometimes listed as more acceptable alternatives.
Legumes and Grains
While many plant-based foods are encouraged, specific legumes and grains are listed as harmful according to the diet. This list includes:
- Kidney beans
- Lima beans
- Garbanzo beans
- Certain wheat products like wheat bran and shredded wheat
- White flour and wholewheat flour
Other Foods and Beverages
The diet also makes claims about other consumables. Some interpretations suggest avoiding certain fruits, like bananas and oranges, due to digestibility concerns. For beverages, the diet recommends avoiding:
- Beer
- Soda
- Sparkling water
- Caffeine (in some cases)
The Scientific Consensus: Lack of Evidence for the Blood Type Diet
Despite its enduring popularity, the blood type diet, and its specific recommendations for A+ individuals, lacks scientific validation. A comprehensive 2013 review of the existing literature found no evidence to support the diet's health claims. Subsequent studies have also failed to prove a link between blood type and diet effectiveness. Any perceived health benefits, such as weight loss or improved blood pressure, are more likely due to the diet's general emphasis on whole, unprocessed foods and increased exercise, a finding that holds true regardless of a person's blood type. Health experts overwhelmingly consider the blood type diet to be a fad, cautioning against its restrictive nature.
The Blood Type Diet vs. Evidence-Based Nutrition
| Feature | Blood Type Diet for A+ | Evidence-Based Nutrition |
|---|---|---|
| Scientific Basis | Primarily based on a theory about lectins and ancestral eating patterns, lacking clinical trial support. | Supported by extensive clinical research, nutritional science, and population studies. |
| Dietary Focus | Highly restrictive, eliminating entire healthy food groups like red meat and dairy unnecessarily. | Encourages a balanced intake of all food groups, emphasizing variety and moderation for comprehensive nutrition. |
| Observed Benefits | Improvements in health markers (if any) are likely caused by cutting processed foods, not blood type-specific factors. | Health benefits are directly linked to the nutritional quality of the diet, which includes plenty of fruits, vegetables, and whole grains. |
| Personalization | Uses a person's blood type as the primary, unproven determinant for dietary choices. | Considers individual needs, health conditions, genetics, lifestyle, and preferences, guided by qualified health professionals. |
Conclusion: Making Informed Dietary Choices
For those wondering what not to eat with A+ blood type based on the blood type diet, the scientific consensus is clear: there is no evidence to support its claims. The diet's list of foods to avoid is based on a debunked theory rather than sound nutritional science. While the diet's emphasis on whole, fresh foods can lead to some positive health outcomes, these benefits are independent of blood type and can be achieved through a less restrictive, evidence-based approach. The most effective way to determine the best diet for your body is to consult a registered dietitian or healthcare provider who can offer personalized, scientifically sound nutritional advice, rather than relying on a dietary plan based on blood type. The focus should be on building a balanced and sustainable eating pattern that works for your unique needs and health goals. For more in-depth information, the systematic review that found no evidence for the blood type diet's effectiveness can be found here: American Journal of Clinical Nutrition review.
