This is the first I'd heard that caffeine might be a PCSK9 inhibitor. Searching for "caffeine pcsk9" brought up (among other studies) Caffeine blocks SREBP2-induced hepatic PCSK9 expression to enhance LDLR-mediated cholesterol clearance. Note that the PSSK9 reduction was shown in a “cohort of healthy volunteers” but isolating the mechanism to the endoplasmic reticulum (via intracellular calcium ion levels) in liver cells was done in vitro.

Many thanks for this — another rabbit hole to dive into. :-)