Observed benefits of plant-based diets may be confounded by factors like increased exercise, sunlight exposure, higher socioeconomic status, and reduced smoking/drinking.

“perhaps it is something else that people who are eating plant-based diets are doing in their life that is causing a benefit this is an association not causation not a causative inference and in fact in these studies there is a good amount of evidence to suggest that these are what are called healthy user bias affected or confounded studies”