Stop focusing on the additives. It would be nice and convenient and comfortable if we could just lose certain preservatives or swap out certain ingredients and magically be healthy without actually changing our diets, but that's not going to happen.

We need to stop eating so much junk food. The densely packed fat, salt, and sugar are always going to be bad for us. Find ways to encourage healthy eating, especially getting kids into the habit of it and making good food just as affordable per calorie as the junk, and you will massively help with the health problems.