Cindy Geyer

Small HDL particles are less capable of clearing LDL particles and facilitating reverse cholesterol transport than larger HDL particles.

"The same is true for HDL. We've historically thought of HDL as being the good, healthy cholesterol, but size matters there, too. Small HDL doesn't seem to be as able to cart out the bad LDL and get rid of it." (said at 0:10:12)

The speaker states the relationship between HDL particle size and cholesterol removal backwards. In reverse cholesterol transport, small, dense HDL particles (such as discoidal HDL and pre-beta HDL) are the primary and most potent mediators of cellular cholesterol efflux via the ABCA1 (ATP-binding cassette transporter A1) pathway. Experimental and clinical studies consistently demonstrate that cholesterol efflux capacity increases as HDL particle size decreases, with small HDL particles displaying 3- to 5-fold greater efflux capacity than larger HDL subfractions.

• contradicts: Flipped C-Terminal Ends of APOA1 Promote ABCA1-Dependent Cholesterol Efflux by Small HDLs. (Circulation 2024) · cited 37x in the literature

  "In both the LCAT-deficient subjects and control subjects, the CEC of isolated extra-small HDL (a mixture of extra-small and small HDL by calibrated ion mobility analysis) was 3- to 5-fold greater than that of the larger sizes of isolated HDL. Incubating LCAT-deficient plasma and control plasma with human LCAT converted extra-small and small HDL particles into larger particles, and it markedly inhibited CEC." (abstract, results, passage verified)

  pubmedfull study (doi)
• contradicts: Distinct roles of size-defined HDL subpopulations in cardiovascular disease. (Current opinion in lipidology 2025) · cited 10x in the literature

  "Small HDL particles are more effective than larger particles at promoting cellular cholesterol efflux because apolipoprotein A-I on their surface better engages ABCA1 (ATP binding cassette subfamily A member 1)." (abstract, results, passage verified)

  pubmedfull study (doi)