Excessive levels of which type of cholesterol are generally seen as harmful?

The correct answer is LDL, or low-density lipoprotein. LDL is often referred to as "bad cholesterol" because elevated levels of LDL are associated with an increased risk of atherosclerosis, heart disease, and stroke. LDL particles transport cholesterol from the liver to the cells, but when there is an excess of LDL in the bloodstream, it can lead to the accumulation of cholesterol in the arterial walls, forming plaques. This buildup narrows the arteries and can impede blood flow or lead to cardiovascular events.

In contrast, HDL, or high-density lipoprotein, is known as "good cholesterol" because it helps transport cholesterol away from the arteries and back to the liver for processing and excretion. Higher levels of HDL are generally seen as protective against heart disease.

Triglycerides are another type of fat in the blood, and while high levels can also contribute to cardiovascular disease, they are distinct from cholesterol. VLDL, or very-low-density lipoprotein, primarily carries triglycerides and is also considered a type of "bad" lipoprotein, but its impact on cardiovascular risk is generally less emphasized compared to LDL.

Thus, excessive levels of LDL cholesterol are considered particularly harmful due to their direct association with increased cardiovascular risk.