I think there was some correct nutrition knowledge around in the late '50s and '60s that was supplanted by all the cholesterol/dietary fat advice that came along later.
My mother used to say that too many "starches" were not good for a person, and she never allowed soft drinks to be bought and kept in the home. She limited sweets and refined carbohydrates.
Carbonated sugar water was rare in our household as well. “Empty calories, with zero nutritional value” was mom’s quote on the matter. These days, do mothers even care what they feed their kids?
To this day, it is really rare that I consume soda pop.