Thats how the health benefits were discovered, a statistical anomaly - a particular region had substantially lower rates of cardiovascular disease despite having a very rich "Mediterranean" cuisine.
Fortunately my country produces great quantities of resveratrol... well in wine
Actually, a great many
phytochemicals, not just resveratrol, have proven their worth many times over in helping prevent a great many diseases.
We used to get a lot more of these beneficial nutrients in our diets but the food many people eat today is grown and processed in ways that have led to our exposure to many beneficial nutrients being much reduced.
Also several of the beneficial effects were discovered, like the above, because the people in one region or another had a statistically obvious lower rate of some common health problem.
That is also the case with curcumin and Alzheimers, BTW. It seems to prevent Alzheimers disease, and some curcuminoids may also be useful in treating it.
I'll try to find a good example of a list of all the
phytonutrients currently known to be beneficial. It would be a very long list.
One good source of info on nutrition is
https://ajcn.org.
There are a great many other good sources of information as well. It helps to suck in as much info as you can, learning what sources are more likely to be useful, rather than applying any one strategy. Unfortunately, lots of papers are questionable, or lack any kind of peer review. Also sometimes, especially when well entrenched interests might be involved, some 'reputable' 'experts' are wrong too, or seem to have some hidden agenda. Sometimes questions are not so easily answered right away by consulting the literature. Science always has open questions. They tend to be resolved by anomalies where existing knowledge is inconsistent and doesn't explain things that well. Thats what makes it so interesting.