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

OBJECTIVE: To assess correlations between cruciferous vegetable intake and urinary isothiocyanate (ITC) level, in addition to glutathione S-transferase (GST) genotypes and other individual factors. DESIGN: The study included cohort participants whose urinary ITC levels had been previously ascertained. Urinary ITC was assessed using HPLC. Usual dietary intake of cruciferous vegetables was assessed using a validated FFQ and total dietary ITC intake was calculated. Recent cruciferous vegetable intake was determined. GST genotypes were assessed using duplex real-time quantitative PCR assays. Spearman correlations were calculated between the covariates and urinary ITC levels and linear regression analyses were used to calculate the mean urinary ITC excretion according to GST genotype. SETTING: Urban city in China. SUBJECTS: The study included 3589 women and 1015 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 (r s=0.1149; P<0.0001), while self-reported recent intake was more strongly correlated with urinary ITC (r s=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: The 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, glutathione S-transferase polymorphisms, and the risk of colorectal cancer among Chinese men.

PURPOSE: To assess the associations between cruciferous vegetable (CV) intake, GST gene polymorphisms, and colorectal cancer (CRC) in a population of Chinese men. METHODS: Using incidence density sampling, CRC cases (N = 340) diagnosed before December 31, 2010 within the Shanghai Men's Health Study were matched to noncases (N = 673). CV intake was assessed from a food frequency questionnaire and by isothiocyanate levels from spot urine samples. GSTM1 and GSTT1 were categorized as null (0 copies) versus non-null (1 or 2 copies). Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals for the association between CV intake and GST gene variants with CRC, and statistical interactions were evaluated. RESULTS: CRC risk was not associated with CV intake, whether measured by self-report or by urinary isothiocyanate nor with GST gene variants. No statistical interactions were detected between CV intake and GST gene variants on the odds of CRC. Stratifying by timing of urine sample collection and excluding CRC cases diagnosed in the first 2 years did not materially alter the results. CONCLUSIONS: This study provides no evidence supporting the involvement of CV intake in the development of CRC in Chinese men.

A meta-analysis identifies new loci associated with body mass index in individuals of African ancestry.

Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one new locus at 5q33 (GALNT10, rs7708584, P = 3.4 × 10(-11)) and another at 7p15 when we included data from the GIANT consortium (MIR148A-NFE2L3, rs10261878, P = 1.2 × 10(-10)). We also found suggestive evidence of an association at a third locus at 6q16 in the African-ancestry sample (KLHL32, rs974417, P = 6.9 × 10(-8)). Thirty-two of the 36 previously established BMI variants showed directionally consistent effect estimates in our GWAS (binomial P = 9.7 × 10(-7)), five of which reached genome-wide significance. These findings provide strong support for shared BMI loci across populations, as well as for the utility of studying ancestrally diverse populations.

Obesity, age, and oxidative stress in middle-aged and older women.

Recent evidence suggests that urinary F(2)-isoprostanes (F(2)-IsoPs) are more accurate markers of oxidative stress than other available biomarkers. Most previous studies used unmetabolized F(2)-IsoPs as a biomarker. Few previous studies measured 15-F(2t)-IsoP-M, a metabolite of one of the most common F(2)-IsoPs, 15-F(2t)-IsoP. Unlike 15-F(2t)-IsoP, 15-F(2t)-IsoP-M is not subject to autoxidation and renal production. To our knowledge, no study has compared the associations of age and body mass index (BMI) with F(2)-IsoPs to those with 15-F(2t)-IsoP-M. Urinary levels of F(2)-IsoPs and 15-F(2t)-IsoP-M were measured using gas chromatography-mass spectrometry for 845 healthy women aged 40-70 years. Both F(2)-IsoPs and 15-F(2t)-IsoP-M were elevated among smokers. The level of 15-F(2t)-IsoP-M increased with age, particularly after menopause, and with BMI. In contrast, F(2)-IsoPs decreased with age, regardless of menopausal status, and was not related to BMI. The association of 15-F(2t)-IsoP-M with age or menopausal status did not differ by BMI category, and the association with BMI was also independent of age or menopausal status. 15-F(2t)-IsoP-M appears to be a valuable biomarker of oxidative stress in age- and obesity-related diseases.