When substituted for saturated fats in the diet, which of the following oils will likely lower total cholesterol but also lower HDL cholesterol?

When considering oils that can substitute for saturated fats and potentially lower total cholesterol while also lowering HDL cholesterol, safflower oil is notable. This is primarily because safflower oil is high in polyunsaturated fatty acids (PUFAs), which are known for their cholesterol-lowering effects.

When PUFAs replace saturated fats in the diet, they contribute to lowered levels of low-density lipoprotein (LDL) cholesterol, which is the "bad" cholesterol. However, research has shown that while polyunsaturated fats can be beneficial for lowering total cholesterol, they may also lead to a reduction in high-density lipoprotein (HDL) cholesterol, the "good" cholesterol. This phenomenon suggests that while the oil effectively reduces total cholesterol levels, it may not always do so in a manner that is beneficial for HDL levels.

In contrast, other oils such as olive oil and canola oil contain monounsaturated fats, which are associated with having a more favorable effect on HDL cholesterol levels. Peanut oil also has a more neutral impact in this regard. Thus, the unique composition of safflower oil leads it to lower both total and HDL cholesterol when substituted for saturated fats.