title: Serum concentration of 27-hydroxycholesterol predicts the effects of high-cholesterol diet on plasma LDL cholesterol level.
abstract: OBJECTIVE
  The effect of dietary cholesterol on plasma cholesterol concentrations varies widely among individuals. Recent studies suggest that the synthesis of oxysterols is up-regulated when tissue cholesterol is saturated. The present study was undertaken to test the hypothesis that a serum high concentration of 27-hydroxycholesterol, one of the oxysterols, reflects positive cholesterol balance in the body and predicts intolerance to a high-cholesterol diet.
  
  
  METHODS
  In 30 subjects, 750 mg/day of cholesterol was added for 4 weeks to the ordinary diet. Blood samples were collected at the start and finish of the supplementation. Serum sterol and oxysterol concentrations were measured by high-resolution GC-MS.
  
  
  RESULTS
  A receiver operating characteristic curve was drawn and the cutoff point (80 ng/mg cholesterol) was chosen to maximize sensitivity (81.3%) and specificity (64.3%) for predicting a positive change of LDL cholesterol concentration after cholesterol loading. Subjects with higher serum 27-hydroxycholesterol concentrations (>/= 80 ng/mg cholesterol) showed significantly (P < 0.05) high values for the change of LDL cholesterol concentration (+7.4 +/- 3.4%, mean +/- SEM, n = 17) compared with those with lower 27-hydroxycholesterol levels (-5.3 +/- 2.7%, n = 13).
  
  
  CONCLUSIONS
  In subjects with high serum 27-hydroxycholesterol concentrations were unable to adapt to a high-cholesterol diet. The concentration of serum 27-hydroxycholesterol appears to reflect cholesterol saturation in the body and predicts to some extent a responsiveness to dietary cholesterol.
authors.affiliation: Department of Gastroenterology, Tokyo Medical University, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hirayama
authors.forename: Yuji
authors.initials: Y
authors.lastname: Mizokami
authors.forename: Akira
authors.initials: A
authors.lastname: Honda
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Homma
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ikegami
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Saito
authors.forename: Teruo
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Matsuzaki