Which is the bad cholesterol, Low-Density Lipoprotein (LDL) or High-Density Lipoprotein (HDL)?

LDL is the "Bad" Cholesterol, While HDL is the "Good" Cholesterol

LDL (Low-Density Lipoprotein) is considered the "bad" cholesterol because it contributes to plaque buildup in your arteries, increasing your risk of cardiovascular disease. In contrast, HDL (High-Density Lipoprotein) is known as the "good" cholesterol because it helps remove other forms of cholesterol from your bloodstream.

Understanding the Different Types of Cholesterol

LDL Cholesterol (Bad)

• Transports cholesterol from the liver to tissues throughout the body
• Contributes to atherosclerosis (plaque buildup in arteries)
• High levels are strongly associated with increased risk of coronary heart disease (CHD) 1
• Target levels vary based on cardiovascular risk:
  • Very high risk patients: <70 mg/dL (1.8 mmol/L)
  • High risk patients: <100 mg/dL (2.5 mmol/L)
  • Moderate risk patients: <115 mg/dL (3.0 mmol/L) 1

HDL Cholesterol (Good)

• Transports cholesterol from tissues back to the liver for disposal (reverse cholesterol transport)
• Has protective effects against cardiovascular disease
• Low levels are associated with increased cardiovascular risk
• Low HDL is defined as <40 mg/dL (1.0 mmol/L) in men and <45 mg/dL (1.2 mmol/L) in women 1, 2

Why LDL is Considered "Bad"

LDL cholesterol is considered harmful because:

• It can build up in artery walls, forming plaques that narrow and harden arteries
• High LDL levels are directly associated with increased risk of coronary heart disease 1
• Very high LDL levels (≥190 mg/dL) are associated with 1.49 times higher risk of cardiovascular mortality compared to normal levels 3
• LDL particles, particularly small, dense LDL particles, are highly atherogenic 4

Why HDL is Considered "Good"

HDL cholesterol is considered beneficial because:

• It helps remove excess cholesterol from the bloodstream
• It transports cholesterol back to the liver for recycling or disposal 5
• Higher HDL levels are associated with lower cardiovascular risk 6
• It has anti-inflammatory and antioxidant properties

Clinical Implications

Understanding the difference between LDL and HDL is crucial for cardiovascular risk assessment and treatment decisions:

• Primary target of cholesterol-lowering therapy is LDL cholesterol 1
• Even at very low LDL levels (<70 mg/dL), HDL remains predictive of cardiovascular events 6
• Non-HDL cholesterol (total cholesterol minus HDL) is another important measure that includes all atherogenic lipoproteins 1

Common Pitfalls to Avoid

1. Focusing only on total cholesterol: Total cholesterol can be misleading since it includes both "good" and "bad" cholesterol. Always consider the full lipid profile.

2. Ignoring triglyceride levels: High triglycerides (>150 mg/dL) often accompany low HDL and can indicate metabolic syndrome 1.

3. Overlooking LDL particle number: Two people with the same LDL cholesterol level may have different numbers of LDL particles and therefore different cardiovascular risk 4.

4. Assuming extremely low LDL is always beneficial: Very low LDL levels (<70 mg/dL) have been associated with increased all-cause mortality and stroke mortality in some studies 3.

Remember that while HDL is generally protective, there is currently insufficient evidence to establish specific HDL targets for therapy 1, 2. The primary focus of lipid management remains on reducing LDL cholesterol to appropriate targets based on individual cardiovascular risk.