"Scientists are supposed to start with a hypothesis, which can then
be tested."
That's only one way of doing science - the simplest stuff.
"When it comes to the food that people eat, there are so many
components hitting the body at the same time it is difficult to
determine the cause."
That's when a host of other scientific methods get used, beginning
with straight old-fashioned curiosity and the filling of notebooks
with observations.
The paper I mentioned is another scientific method: a review paper, a
summing up of what is known and what isn't.
"'olive oil' is not one thing"
True, especially the extra virgin grades bottled in glass in Italy
that I collect - they vary as much as fine wines. And yes, I keep
them in the frig and scoop them out with a cake knife. Well worth the
bother. It's just that I now count them as having 400 mg/100g
cholesterol equivalent - one number in my 200x48 matrix.
I'll start looking for useful data on free radical, antioxidant, and
phenol content of foods...