I'm going to completely fail at giving you an accurate picture of what he says... But the gist might be that, empirically, traditional foods and eating habits are more healthy than the American diet that's based on the industrial food chain. Traditional foods are not just vegetables grown in real dirt, but also includes things like beef that was grass fed on open range, instead of corn-based feed in an industrial farm. He criticizes selecting food based on advertised nutritional information, claims of low fat this or that, vitamin-enriched, etc. Recently he refers to the dominant view of nutrition as "nutritionism," that a healthy diet can be found by analyzing all of the components of what you eat in terms of vitamins, fats, minerals, fiber, etc. Basically, if it comes in a box with a label that says how good it is for you, don't eat it.
Since you're in a agreement that "curing" death would require scientific advances in food production in order to support the increased population, I thought I'd throw it out there that the scientific advances in food production we already have are partly responsible for the degradation of American diet quality.