> My comment is that it is not ONLY low fiber diets.

Well, you said "can't" and I asked "why", which feels very reasonable to me. Your argument seems to be that it wouldn't account properly for the data - specifically, you're saying we would have seen colon cancer rates rise earlier.

> Western diet collapsed its fiber intake well over 80 years ago - it would have shown up already.

I don't really buy this for a lot of reasons. Probably the two most important are (a) ability to screen historically and (b) the timing isn't particularly "off" for the fiber argument. We did see it already, we've been seeing increases in color cancer risks for decades.

Now, I'm not married to it "just" being fiber whatsoever, but if I were to "bet" on the major contributing factor, naively, that's where my money would go. I think it's very reasonable to not place your bet there.

Should be a betting service for this kind of thing instead of sports betting. Maybe all the men betting sports might read and change their habits based on the betting outcomes (and improve their health).

I would also bet top reason is fiber but it isn't the only reason - multiple factors at play.