【单句求助】红字部分如何翻译

How did the original USDA（美国农业部）pyramid go so wrong? In part, nutritionists fell victim to a desire to simplify their dietary recommendations. Researchers had known for decades that saturated fat—found in abundance in red meat and dairy products—raises cholesterol levels in the blood
其他部分无问题，只是不知红字部分如何翻译。