It does say "protect against," though, which to me raises the question of "protects against to what extent?" Which, related to your point about collections of

It does say "protect against," though, which to me raises the question of "protects against to what extent?" Which, related to your point about collections of interacting genes: I ran a Promethease report on my genetic data, and it said I had 15-20 different genes associated with an elevated risk of a particular autoimmune disease that I do, in fact, currently suffer from. So in a case like that, I suspect (but obviously can't say for sure) that protective diets have a much harder battle to fight than for someone who doesn't have all those genes.