Proponents of the blood type diet claim that people with type A blood benefit most from a vegan diet. However, a new study found no link between diet and blood type. The researchers instead suggest that plant-based diets are beneficial for people of all blood types.
Study outcomes
At the start of the trial, body weight and low-density lipoprotein (LDL) cholesterol levels were higher in people with blood type A than in those with other blood types. In contrast, body weight and LDL cholesterol levels were lower in people with blood type O than in those with other blood types.
There were no significant differences between blood type and the changes that resulted from the vegan diet.
Study strengths and limitations
There were multiple strengths to the study, starting with ruling out possible confounders that could influence the results.
For instance, to exclude physical activity as a factor, participants maintained their regular exercise routine during the 16-week trial. Also, all participants started the trial simultaneously, which ruled out seasonal changes in diet.
According to the researchers, 16 weeks was a suitable time for participants to acclimate and adhere to the study. There was also a low drop-out rate.
The participants did not have access to ready-prepared meals but could prepare food at home or opt for take-out. This method made the findings more applicable to real-life conditions.
However, there were major limitations regarding representation
Takeaway: A lack of strong evidence
Overall, the researchers say that their data add to the current body of work consistently finding a lack of strong evidence for the blood type diet.
“These studies, like the present one, suggest that dietary changes, especially increased intake of fruits, vegetables, and grains, are beneficial not only to individuals with blood type A but also to all individuals regardless of blood type, and that there is no apparent value of limiting these healthful diet changes to a specific set of individuals based on ABO blood group.”
