Why are trans fats harmful?

Trans fats are harmful primarily because they have a detrimental effect on cholesterol levels within the body. Specifically, they increase low-density lipoprotein (LDL) cholesterol, often referred to as "bad" cholesterol. Elevated levels of LDL cholesterol are associated with an increased risk of heart disease and stroke due to the tendency for it to contribute to the buildup of plaques in the arteries. In addition to raising LDL cholesterol, trans fats also lower high-density lipoprotein (HDL) cholesterol, known as "good" cholesterol, which is protective against heart disease. Thus, the combination of raising bad cholesterol and lowering good cholesterol creates an unfavorable lipid profile that significantly increases cardiovascular risk.

The other options do not accurately reflect the established effects of trans fats on health. Trans fats do not increase good cholesterol levels, and they certainly do not have a neutral impact on health. Additionally, they do not lower blood sugar levels; instead, their primary concern lies within their influence on cholesterol and heart health.