Generally speaking, nutritional studies are observational and very difficult to control for confounding variables. Think about it this way: "We want to feed g

Generally speaking, nutritional studies are observational and very difficult to control for confounding variables. Think about it this way: "We want to feed group A organic apples, group B apples that have been doused in insecticide, and then use a group C that isn't fed anything." This is already hard - specifically if people are resistant to eating something they perceive as harmful. But now add in further separation for confounding variables: - Weight - Race - Age - Sex - Other foods you eat - Exercise And everything else that can vary drastically from one person to the next. In order to actually perform this study, you would either need A) a VERY large group of people to observe (who haven't opted in to a controlled study) so you can have statistically significant sub-groups that can be stratified into quartiles or whatever (for example, sedentary, low activity, moderate activity, high activity), Or, B) a fair sized group of people who want to opt in to such a restrictive controlled study. Nutrition is something that typically needs to be studied for decades for things that we don't already have a pretty good idea about (like acute allergies, botulism, those kinds of things). We are very unlikely to have this data until we have MUCH better observational data over the course of someone's life. Maybe we will have these points as people born in the early 00's start to grow up with more tracked data available, but can you tell me how many apples you ate per week in 1997? (Quick edit to clarify some confusing language)