One of my Michael Pollan's suggested heuristics for eating is, "Don't eat anything your great-grandmother wouldn't recognize." He uses, as an example, Go-gurt:
which, he speculates, your great-grandmother wouldn't know whether to classify as a food or maybe some kind of balm. He also suggested that, depending on your age, you might need to go back more or less far to find a maternal ancestor who didn't eat the modern western diet.
I decided to go with my great-great-grandmother, and I am also assuming that I had several (this is true, of course) and that they were from a wide variety of cultures (which is probably not true). Since tofu has been eaten for several hundred (possibly thousand) years, it passes muster with my fictional great-great-grandmother, even though I doubt anyone in my actual lineage, above my grandparents, ever ate it.
My fictional GGGM wouldn't recognize some of the ingredients in Go-gurt, such as high fructose corn syrup, tricalcium phosphate, potassium sorbate, or carmine. On the other hand, she would recognize the ingredients of Stonyfield Farm strawberry yogurt: whole milk, strawberries, sugar, pectin, beet juice, natural flavor, and yogurt cultures.
This "rule" (which I'm not following strictly, but more sort of paying attention to) may have some merit on its own, to the extent that foods handed down to us from hundreds of years of culture are well-tested for eating compared to food additives invented in laboratories in this century, but I think it's better as a kind of proxy. Is this a fresh, natural food such as I might make in my own kitchen? If I had these individual ingredients around, would I use them in my cooking?
None of that guarantees healthy eating, of course. But I think, at least for me, trying to cook and/or use fresh, natural foods tends in the direction of healthy eating, because I'm not likely to cure my own ham or start saving up organic bacon grease to cook all of my greens in. My mental image of the kind of cooking and eating I'd like to do is definitely healthy. And it keeps me away from chain restaurant food, which is invariably engineered with mysterious chemicals.
So, thanks, fictional GGGM, for your fantastically healthy, ethnically diverse diet.