It's not just a matter of poor willpower on the part of the consumer and a give-the-people-what-they-want attitude on the part of the food manufacturers. What I found, over four years of research and reporting, was a conscious effort... to get people hooked on foods that are convenient and inexpensive.
Health messages are simply overwhelmed, in volume and in effectiveness, by junk-food ads that often deploy celebrities or cartoon characters to great effect. We may know that eating fruits and vegetables is good for us, but the preponderance of the signals we get - and especially the signals children get - push us in the direction of junk food.
When it comes to salt, what was really staggering to me is that the industry itself is totally hooked on salt. It is this miracle ingredient that solves all of their problems. There is the flavor burst to the salt itself, but it also serves as a preservative, so foods can stay on the shelves for months.