Reproducibility of Dietary Biomarkers in a Multiethnic Asian Population

Abstract

Scope: Dietary biomarkers allow for study of diet and disease risk relationships, but a key requirement is that these biomarkers are reproducible and reflect long-term diet. This study assesses reproducibility of selected dietary biomarkers in a multi-ethnic Asian population, and quantifies diet-disease relationship attenuation arising from use of a single biomarker measurement.

Methods and results: Intra-class correlation coefficients (ICC) are used to evaluate the reproducibility of urinary isoflavone and enterolignan, total plasma fatty acid (FA), and serum carotenoid concentrations measured 4 months apart in adult Singapore residents (ethnic Chinese, n 59; Malay, n 46; Indian, n 56). Total carotenoid ICC is 0.75 (95% confidence interval (CI) 0.68, 0.81), ranging from 0.63 to 0.84 for individual carotenoids. FA ICC (median) is 0.74 (inter-quartile range 0.70-0.78). Total isoflavone ICC (95% CI) is 0.21 (0.06-0.35). Total enterolignan ICC is 0.42 (0.28, 0.54). Attenuation factors associated with a single time point measure ranged from 0.74 to 0.94 for carotenoids and FAs, and 0.42 to 0.70 for isoflavones and enterolignans.

Conclusions: In a multi-ethnic Asian population, single measures of most serum carotenoids and plasma FAs likely represent habitual diet, whereas reproducibility of urinary isoflavones and enterolignans is moderate, possibly due to rapid excretion.

Keywords: biomarkers; carotenoids; isoflavones; reliability; reproducibility.