Small Dense LDL (sdLDL)
The truly atherogenic LDL fraction — penetrates the endothelium better and oxidises more
Definition
Small dense LDL (sdLDL) are LDL-cholesterol particles of subtype III/IV — smaller (<25.5 nm) and denser than large buoyant LDL (lbLDL, subtypes I/II). Their key feature is greater atherogenicity: they penetrate the arterial endothelium more easily, are more susceptible to oxidation (with formation of unstable plaques), have lower affinity for the hepatic LDL receptor (longer plasma residence), and are associated with the 'pattern B' of the metabolic lipid phenotype.
Detailed explanation
Clinical sdLDL measurement requires advanced techniques: NMR-LipoProfile (LipoScience), ion mobility (Quest Diagnostics), or direct sdLDL-C concentration. Generic tests only give total LDL-C. In Spain, private laboratories (Synlab, Eurofins, Echevarne, Cerba) offer advanced NMR profiles at €80-150.
Pattern B (sdLDL predominance) is typical of metabolic syndrome: - High triglycerides (>150 mg/dL) - Low HDL (<40 men, <50 women) - Elevated ApoB - Insulin resistance (high HOMA-IR) - Abundant visceral fat
Two people with the same total LDL-C can have very different cardiovascular risk: one mainly carrying large buoyant LDL and the other small dense LDL — the second has 3-4× higher event risk.
Specific interventions to lower sdLDL (more effective than for total LDL): reduction of refined carbohydrates and free fructose (low-carb diets lower sdLDL even without changes in total LDL), visceral fat loss, aerobic exercise (especially Zone 2), omega-3 (≥2 g/day EPA+DHA), soluble fibre (oats, psyllium), niacin (potent in pattern B but with tolerance limitations), statins combined with omega-3.
Longevity goal: predominance of large buoyant particles (pattern A) with ApoB <60 mg/dL.
Scientific sources
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