I have friends in France that eat heaps of butter each morning and they are not fat, but I am not sure they are healthy either. Many remember the days when butter was slammed and margarine was the appropriate substitute. These days butter is certainly a better alternative and very few people use margarine anymore.
It seems that foods trends based on partial medical evidence eventually becomes status quo. In the end there are good foods and those foods that should be avoided but more importantly portions and frequency of consumption.