HDL
The cholesterol recycling truck. HDL picks up excess cholesterol from tissues and artery walls, returning it to the liver for recycling or excretion. But it's not just about the number - HDL functionality matters as much as the level.
What HDL Does
Reverse Cholesterol Transport
Picks up excess cholesterol from cells and arterial walls, returns it to liver for recycling.
Antioxidant Protection
Carries antioxidant enzymes (PON1) that prevent LDL oxidation. Protects against atherosclerosis.
Anti-Inflammatory
Reduces inflammation in blood vessel walls. Inhibits adhesion molecules that attract immune cells.
Endothelial Health
Promotes nitric oxide production, supporting blood vessel dilation and healthy blood flow.
Anti-Thrombotic
Reduces platelet activation and aggregation, lowering clot risk.
Cell Signaling
Carries signaling molecules and interacts with cellular receptors to regulate various processes.
HDL Quality: Not Just the Number
Drug trials that raised HDL numbers without improving function failed to reduce heart disease. It's not just about HDL-C levels:
Functional HDL
- Efficiently accepts cholesterol from cells
- High PON1 antioxidant activity
- Good anti-inflammatory properties
- Properly sized particles
- Result of healthy lifestyle
Dysfunctional HDL
- Poor cholesterol acceptor capacity
- Oxidized or damaged particles
- Can become pro-inflammatory
- May occur with chronic inflammation
- High number, low benefit
What Actually Raises HDL
Exercise
Most effective intervention. Both cardio and resistance training help. Consistency matters more than intensity.
Weight Loss
Every 6 lbs lost raises HDL by ~1 mg/dL. Reducing visceral fat is especially helpful.
Moderate Alcohol
1-2 drinks/day raises HDL. Not recommended to start drinking for this - risks may outweigh benefits.
Healthy Fats
Olive oil, fatty fish, avocado, nuts. Replacing carbs with healthy fats raises HDL.
Stop Smoking
Smoking lowers HDL and impairs its function. Quitting can raise HDL by 10%.
Reduce Refined Carbs
Sugar and refined carbs lower HDL and raise triglycerides. Low-carb diets often boost HDL.
What Lowers HDL
Metabolic Syndrome
Insulin resistance, high triglycerides, and abdominal obesity all lower HDL.
Sedentary Lifestyle
Lack of physical activity is strongly associated with low HDL.
Smoking
Damages HDL particles and reduces their number and function.
Trans Fats
One of few dietary factors proven to lower HDL. Avoid hydrogenated oils.
High Refined Carbs
Sugar and refined grains lower HDL while raising triglycerides.
Certain Medications
Beta-blockers, anabolic steroids, some progestins can lower HDL.
The Triglyceride/HDL Ratio
This simple ratio from a standard lipid panel predicts cardiovascular risk and insulin resistance:
Ideal. Large, buoyant LDL particles likely. Good insulin sensitivity.
Borderline. Mixed particle pattern. Watch metabolic markers.
High risk. Small dense LDL likely. Indicates insulin resistance.