Which of the following fats should be avoided due to its negative impact on cholesterol levels?

Trans fatty acids should be avoided primarily because they have been shown to raise levels of low-density lipoprotein (LDL) cholesterol, known as "bad" cholesterol, while simultaneously lowering levels of high-density lipoprotein (HDL) cholesterol, known as "good" cholesterol. This dual effect significantly increases the risk of heart disease and other cardiovascular problems. Trans fats are often found in processed foods, baked goods, and margarines, making it essential to minimize their intake for maintaining heart health and optimal cholesterol levels.

In contrast, monounsaturated fats and omega-3 fatty acids are considered beneficial for heart health and can actually help improve cholesterol levels. Saturated fats can have a mixed effect on cholesterol, depending on the individual and the sources of these fats, but they do not contribute to the same detrimental health effects associated with trans fats. Hence, the emphasis on avoiding trans fatty acids provides a clear guideline for improving cholesterol levels and overall cardiovascular health.