The first sentence is setting the scene, not confirming the hypothesis. If things being "known" by cultural history was sufficient, we wouldn't need to do scien

The first sentence is setting the scene, not confirming the hypothesis. If things being "known" by cultural history was sufficient, we wouldn't need to do science. In reality, a good proportion of "known" things are wrong or the very minimum more subtle than expected. It is also "known" that being physically cold causes colds (Mediterraneans are especially paranoid about this in my experience). The majority of studies show this to be either untrue or borderline. I do agree that there is clear potential for chopping food to affect it's nutritional value. I would expect chopping alone to be of minimal impact in most cases if no other evidence was available. Elaborate processing is rather different.