Correlates of self-reported dietary cruciferous vegetable intake and urinary isothiocyanate from two cohorts in China

Abstract

Objective To assess correlations between cruciferous vegetable intake and urinary ITC level, in addition to glutathione S-transferase (GST) genotypes and other individual factors. Design This study included cohort participants whose urinary ITC levels had been previously ascertained. Urinary ITC was assessed using high-performance liquid chromatography. Usual dietary intake of cruciferous vegetables was assessed using a validated food frequency questionnaire and total dietary ITC was calculated. Recent cruciferous vegetable intake was determined. GST genotypes were assessed using duplex real-time quantitative polymerase chain reaction assays. Spearman correlations were calculated between the covariates and urinary ITC levels and linear regression analyses were used to calculate the mean urinary ITC according to GST genotype. Setting Urban city in China Subjects This study included 3,589 women and 1,015 men from the Shanghai Women’s and Men’s Health Studies. Results Median urinary ITC level was 1.61 nmol/mg creatinine. Self-reported usual cruciferous vegetable intake was weakly correlated with urinary ITC level (rs = 0.1149; p < 0.0001), while self-reported recent intake was more strongly correlated with urinary ITC (rs = 0.2591; p < 0.0001). Overall, the GST genotypes were not associated with urinary ITC level, but significant differences according to genotype were observed among current smokers and participants who provided an afternoon urine sample. Other factors, including previous gastrectomy or gastritis, were also related to urinary ITC level. Conclusions This study suggests that urinary secretion of ITC may provide additional information on cruciferous vegetable intake and that GST genotypes are related to urinary ITC level only in some subgroups.

Cruciferous Vegetables and Risk of Cancers of the Gastrointestinal Tract

“…The use of urinary markers to measure dietary exposure to cruciferous vegetables is a potentially valuable advance. Although statistically significant correlations between urinary ITC levels and self‐reported intake of cruciferous vegetables can be detected in human populations, the clearance of glucosinolate breakdown products from plasma is relatively rapid . Spot urine samples are therefore an indicator of recent intake rather than long‐term exposure.…”

“…This detoxification pathway forms part of a complex metabolic network which, as is discussed at length elsewhere in the present volume, is thought to regulate a variety of anticarcinogenic mechanisms, including the induction of ,phase II enzymes that metabolize and help to detoxify environmental carcinogens such as the constituents of tobacco smoke . Another consequence of the rapid metabolism of glucosinolate breakdown products is the appearance in human urine of their metabolites, which can be detected and quantified and used as an objective biomarker of cruciferous vegetable consumption …”

Higher Levels of Urinary Thiocyanate, a Biomarker of Cruciferous Vegetable Intake, Were Associated With Lower Risks of Cardiovascular Disease and All-Cause Mortality Among Non-smoking Subjects

“…Estimating CV intake with quantitative biomarkers has received increasing attention (36,37). Urinary isothiocyanate, another decomposed product of glucosinolates, had been applied in previous studies (36)(37)(38).…”

Associations between cruciferous vegetable intake and selected biomarkers among women scheduled for breast biopsies

“…This finding is understandable given that urinary SFN ITC levels reflect recent intake of SFN, not usual cruciferous vegetable intake, as SFN ITC are eliminated from urine within 48 h after cruciferous vegetable intake (23) . One large study of two cohorts in China, including 3589 women and 1015 men, showed self-reported usual dietary cruciferous vegetable intake was weakly correlated with urinary ITC level (r = 0·1149, P < 0·0001), while recent dietary cruciferous vegetable intake was more strongly correlated with urinary ITC level (r = 0·2591, P < 0·0001) (24) . In our analysis of the relationship between total cruciferous vegetable intake and PBMC HDAC activity, we did not observe a significant correlation.…”