This one I can sorta agree with you and sorta not. Many people's diets aren't necessarily WORSE, but portion control and caloric intake is out of control for a lot of American people. I can agree that the fast food epidemic is pretty bad indeed. Remember those commercials where they show the 50's families with entire sticks of butter on their dinner plates, giant amounts of fried bacon and eggs, etc.... The consumption of fried and fatty foods to healthier foods such as veggies hasn't really gone up - it's just that food is far more available and lifestyle is more sedentary than it was in years past. The exception to this is the addition of High fructose Corn syrup to many foods that was not added before; we are eating far more sugar than ever.
On the other hand, We now have far more dietary supplements, vitamin supplements, foods are specifically chosen for their antioxidant and micronutrient content, vitamins are added to food that previously were not there. Health food stores and herbal teas are mainstream. Doctors tell people to actively pursue healthier eating choices. Nutritionists are popular and did not exist much before the 80's. None of this was true in the past in American culture.