In 2013, a group of researchers undertook just such a study into blood type diets. Scientists can perform a type of study known as a systematic review, where they pool the data from all relevant studies (not just those looking at the specific effect, but also other studies where appropriate data is recorded) and then analyse the effect. Which means a study with “sufficient power” is unlikely to be performed for a dietary intervention. Studies of this size are expensive and very time consuming and so are unlikely to be performed unless they are covering a major health risk. While it’s relatively straightforward to perform a study with 10 or 100 people, it becomes a completely different ball game when you reach 1,000 people or more. To investigate definitively, researchers need to make sure their study is sufficiently powered, which means they need lots of people to perform their comparison. In instances like this we typically say the study is under-powered – don’t worry I won’t go into statistical analysis here, it makes my blood run cold as well… Studies of 10 people might show an effect, but another study on a different 10 people might not. when all sorts of other factors such as individuals genetics or their environment influence outcome.

Issues like this frequently occur in medical research when the underlying effect is multifactorial i.e. Whilst a lot of claims were made about the diet, clinical studies were lacking. In the early 2000’s, diets based on your ABO blood type were all the rage, with the D’Adamo diet being one of the most popular versions.

Yes, the blood type diet is largely thin on evidence, especially after this new study by plant based doctor Neil Barnard showing changes in weight, fasting blood sugar and cholesterol didn’t have anything to do with blood type in a group placed on a low-fat vegan diet.Īlthough, as I will discuss in this post, there are a few narrow redeeming qualities to this much maligned fad diet. Potential dietary changes based on blood type.

Blood type o negative food diet