...
One thing to understand is the difference in the vinification techniques for red and white wines.
Grapes come in many colors (Green, Purple, Black, Gray).
However, wine typically comes in 2 colors (Red and White).
Despite the color of the grape, the juice squeezed from them is primarily clear. The pigments in a grape are found in its skin. So, the process of vinification that makes a red wine is to leave the clear juice (called must) in contact with the skins before, during, and sometimes after the fermentation process. During this period (called maceration), the must removes pigments, tannins, and many other compounds from the skins (basically like osmosis).
With white wines, the juice is racked (moved) into vats that keep the must separated from the skins. This process keeps the juice from absorbing the pigments, tannins, and other compounds that could be found in the skins.
Some white wines are aged sur-lie, meaning in contact with the skins. As far as I know, this is always done with white wines that come from light colored grapes. In this way, the whites can extract character from the skins without picking up dark pigments.
Okay, that's probably too much info for now, but let's synthesize it quickly.
With most produce, nutritionists will tell you that the most beneficial compounds are found in the skin. So, the more you separate your food from its skin, the less beneficial the food is from a health perspective.
So, it makes some sense that red wines and whites that are aged sur-lie would pick up more of the beneficial compounds from the skin of the fruit.
The last factor is how the wine is fined/filtered. It's possible to remove pigments from a wine (pinot grigio is often a gray juice before the pigments are removed).
It remains to be seen whether the fining/filtering process removes any beneficial compounds.
So, white vs. red may not be the issue. Rather, it may be that two reds or two whites could have significantly different health values based upon the vinification techniques employed in its production.
Wow. I can barely understand what I just typed, so I hope you guys are smarter than I.