What is a blood type diet?

A blood type diet is a nutritional theory that states that you will be healthier if you eat according to your blood type (A, B, AB or O).

The diet was developed in the 1990s by Peter D’Adamo, an American naturopath. His theory is that each blood type reacts differently to certain foods. This is believed to be related to evolutionary development, digestion, and the immune system. An incorrect diet is believed to lead to inflammation, weight gain, and disease.

For example, people with blood type O should eat a lot of meat and fish and few grains and dairy. People with blood type A should eat little meat and more grains, vegetables, and legumes. Dairy products are recommended for blood type B, and certain meats, such as chicken, are discouraged. People with blood type AB follow a combination of A and B with moderate meat, fish, and dairy consumption.

There is no robust scientific evidence that the blood type diet works. Large reviews and studies show that the health benefits are primarily due to a generally healthy diet, not to blood type coordination. Doctors and dietitians do not recommend the diet as a medical treatment.

The blood type diet links food to your blood type. It's popular, but not scientifically proven. It can be unnecessarily restrictive. A generally healthy, varied diet is more well-founded.

Source: https://www.sciencedirect.com/science/article/pii/S0002916523051377

Author: Prof. Dr. Dirk Devroey - Latest update: 2025-12-20 - Copyright: Clinifacts 2026