O-1 - 69% of metabolic-ward diet periods compensated for added dietary cholesterol; ~31% showed a plasma-cholesterol rise
Direct-measurement metabolic-ward design: fractional cholesterol absorption and sterol synthesis (in isolated blood mononuclear leukocytes) were measured in each of 75 twelve-week diet periods, alongside plasma lipids. The 69/31 split is a per-period compensation frequency, not a per-subject genotype count (exact subject n not recoverable from the accessible text). Depth-limited: full text is available only as scanned page images; extraction rests on the abstract plus the step-2 node summary.
Link to originalMethodology
Metabolic-ward controlled feeding across 75 twelve-week diet periods. Each period supplied 35% of calories as either saturated or polyunsaturated fat, tested first low and then high in dietary cholesterol. During every period the study measured dietary fat and cholesterol intake, plasma lipid and lipoprotein levels, cholesterol fractional absorption, and sterol synthesis in isolated blood mononuclear leukocytes (a proxy for whole-body endogenous synthesis). Depth-limited read: the full text is accessible only as scanned page images, so exact subject n and per-dose cholesterol amounts are not recoverable; extraction rests on the verbatim abstract plus the step-2 node summary.
Link to original
Why this is evidence
A clean 69/31 split with the majority holding plasma cholesterol flat by measured down-regulation of absorption/synthesis is what H-1 (discrete hypo/hyper split, ~31% hyper) and H-2 (feedback buffering is the mechanism) predict. H-35 (continuous normal trait) predicts a smooth spread with no natural break — the dichotomy is at most a threshold cut of a continuum. H-55 (largely noise/regression to the mean) is undercut because the split tracks a measured physiological compensation, not just response scatter.