In 1996, Dr. Peter D'Adamo published "Eat Right for Your Type," a book based on the idea that people with different blood types thrive on different kinds of diets. If you ask D'Adamo, coconut oil is good for blood group O. However, there's no real scientific evidence to support his claims.
Researchers have looked into the Blood Type Diet and found that while many people do report benefits when following the diet, it's unrelated to their blood type and is, instead, a result of incorporating new healthy dietary and lifestyle changes.
According to the Blood Type Diet, people with the blood type O thrive on fats, like coconut oil, as well as high-quality protein. However, there's no scientifically supported evidence that the Blood Type Diet works.
Blood Type O Diet Food List
Dr. D'Adamo designed his first book, "Eat Right for Your Type," around the four blood types: A, B, AB and O. According to Harvard Health Publishing, the theory behind the Blood Type Diet is that your blood type affects the way you digest foods. By following the proper diet for your blood type, you'll have improved digestion, better energy levels and an easier time maintaining your ideal body weight.
Based on this information, D'Adamo developed four diet plans that were designed for optimal health of each blood type. He believed people with blood type O have higher levels of stomach acid and an enhanced ability to digest protein and fats, like coconut oil, but have a harder time with high-carbohydrate foods, like potatoes and grains. According to the Blood Type Diet, a blood type O diet food list looks something like this:
Read more: How to Help an O Blood Type Lose Weight
But Does It Work?
Although many people have reported feeling great and noticed improvements in their digestion and energy levels, when following a diet designed specifically around their blood type, there's no scientific evidence that the Blood Type Diet actually works.
Researchers from a systematic review that was published in the American Journal of Clinical Nutrition in May 2013 looked over all of the existing research and concluded that "no evidence currently exists to validate the purported health benefits of blood type diets."
A review in the January 2014 issue of PLOS One investigated this a little further and found that following the Blood Type Diet could improve certain health markers like triglycerides, insulin levels and cholesterol, but it was unrelated to blood type.
In other words, people following the outlined diets for the different blood types had improvements in their health even if they weren't following the diet for their blood type. For example, people with blood type O following a blood type AB diet may still notice improvements.
In fact, you'd likely notice improvements no matter which "diet" you were following, as long as you're making a new, healthy lifestyle change. In one study that was published in the Journal of the American Board of Family Medicine in January 2012, researchers concluded that basic diet and lifestyle changes, like eating more than five servings of fruits and vegetables, limiting alcohol, not smoking and exercising regularly, could significantly improve your health, even if you're not overweight.
So, how do you explain the anecdotal evidence? Some researchers speculate that people feel great on the diet because each of the four plans is based around healthy, whole foods and cuts out things like refined carbohydrates and sugar.
The Blood Type Diet also goes a step beyond food and provides recommendations for other healthy lifestyle strategies for each blood type, like figuring out ways to manage stress and incorporating the right daily exercise — things that could positively benefit everyone, regardless of their blood type.
- Dr. Peter D'Adamo's Blood Type Diet: "Blood Type O"
- Harvard Health Publishing: "Diet Not Working? Maybe It’s Not Your Type"
- PLOS One: "ABO Genotype, ‘Blood-Type’ Diet and Cardiometabolic Risk Factors"
- American Journal of Clinical Nutrition: "Blood Type Diets Lack Supporting Evidence: A Systematic Review"
- Journal of the American Board of Family Medicine: "Healthy Lifestyle Habits and Mortality in Overweight and Obese Individuals"