However, there are some dietary risk factors which do seem to be associated with blood type, which can be influenced by certain dietary choices.īut before we look at that it’s worthwhile to go over the ABO blood classification as this can give us some idea where the initial blood type diet hypothesis came from, and how it might be relevant for other studies. In that respect, the blood type diet has been debunked. So is that the end? Are blood type and diet definitively not linked? Well in the sense that you should follow a particular diet based on your blood type, yes. D’Adamo’s protocols would be healthier on a diet with more animal protein.īased on the cardiometabolic markers studied, this turned out not to be the case, which may have put the final nail in the coffin for the blood type diet, at least within the scientific community. The idea with this study was that, in theory, the low fat vegan diet well suited to type A blood types and not as well suited for those with type O blood, who under the rules of Dr. Most participants saw improvements, it’s just that no one group saw greater results for cholesterol, BMI, fasting blood sugar, HbA1c, or weight loss than another due to blood type. Barnard is a staunch advocate of plant based diets, and his blood type diet study shows no enhanced benefit for blood type A on a low-fat vegan diet vs. Barnard’s recent study follows in the same vein as the 2013 analysis I discuss above.ĭr. Dr D’Adamo refutes this study on his site but once again, in a non peer review format.ĭr. This study was considered the nail in the coffin of the blood type diet. Rather, it is just an effect of following a traditional “healthy” diet. So, while a positive effect from following the low meat high fruit and vegetable diet was observed, this was not associated with any particular blood group. Our findings show that adherence to certain ‘Blood-Type’ diets is associated with a favorable profile for certain cardiometabolic risk factors in young adults, but these associations were not related to an individual’s ABO blood group. 3 Again the paper has a lot of detail and is perhaps again summed up best by the authors: This systematic review was followed up by a direct study investigating blood type diet and its impact on cardiometabolic risk factors in 1,455 individuals. None of the studies showed an association between ABO blood type diets and health-related outcomes. 2 The paper itself is quite difficult to follow so I’ll just take this quote from the authors: 1 After screening 1,415 studies they identified 16 possible targets, which the further refined down to a single study of interest. 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.

O negative blood type diet lectins