July 1976, the Select Committee on Nutrition and Human Needs:

“The simple fact is that our diets have changed radically within the last 50 years …,” McGovern said when the report was released. “These dietary changes represent as great a threat to public health as smoking. Too much fat, too much sugar or salt, can be and are linked directly to heart disease, cancer, obesity, and stroke, among other killer diseases. In all, six of the ten leading causes of death in the United States have been linked to our diet.

http://www.truthdig.com/report/item/eating_our_way_to_disease_201707091