The USDA is the United States Department of Agriculture.
Their sole interest is to support the agricultural industry, not to promote human health.
Ever since the USDA assumed the role of psuedo-nutritionists, America's grain and processed food consumption has skyrocked, due to the unfair subsidization of commodity crops. This has resulted in dramatic increases in Heart Disease, Diabetes, poor nutrition, poor practices with feedlot raised cattle, and goverment enforced nutrient deficient school lunches laden with Gluten, Casein, Soy, Sugar, and additives.
If anyone should be advising Americans what to eat, it should be a well-represented group of nutritionists with a degrees in biology or chemistry, or no one at all. Least of all, someone with ulterior motives.