Comparison of phytosterol intake from FFQ with repeated 24-h dietary recalls of the Adventist Health Study-2 calibration sub-study.

We evaluated the performance of an FFQ in estimating phytosterol intake against multiple 24-h dietary recalls (24HDR) using data from 1011 participants of the calibration sub-study of the Adventist Health Study-2 (AHS-2) cohort. Dietary assessments of phytosterol intake included a self-administered FFQ and six 24HDR and plasma sterols. Plasma sterols were determined using the GLC flame ionisation method. Validation of energy-adjusted phytosterol intake from the FFQ with 24HDR was conducted by calculating crude, unadjusted, partial and de-attenuated correlation coefficients (r) and cross-classification by race. On average, total phytosterol intake from the FFQ was 439·6 mg/d in blacks and 417·9 mg/d in whites. From the 24HDR, these were 295·6 mg/d in blacks and 351·4 mg/d in whites. Intake estimates of β-sitosterol, stigmasterol, other plant sterols and total phytosterols from the FFQ had moderate to strong correlations with estimates from 24HDR (r 0·41-0·73). Correlations were slightly higher in whites (r 0·42-0·73) than in blacks (r 0·41-0·67). FFQ estimates were poorly correlated with plasma sterols as well as 24HDR v. plasma sterols. We conclude that the AHS-2 FFQ provided reasonable estimates of phytosterol intake and may be used in future studies relating phytosterol intake and disease outcomes.