Mengmeng Du

Trends in Dietary Supplement Use Among US Adults From 1999-2012.

Importance Dietary supplements are commonly used by US adults; yet, little is known about recent trends in supplement use. Objective To report trends in dietary supplement use among US adults. Design, Setting, and Participants Serial cross-sectional study using nationally representative data from the National Health and Nutrition Examination Survey (NHANES) collected between 1999 and 2012. Participants include noninstitutionalized adults residing in the United States, surveyed over 7 continuous 2-year cycles (sample size per cycle, 4863 to 6213). Exposures Calendar time, as represented by NHANES cycle. Main Outcomes and Measures In an in-home interview, participants were queried on use of supplements in the preceding 30 days to estimate the prevalence of use within each NHANES cycle, and trends were evaluated across cycles. Outcomes included use of any supplements; use of multivitamins/multiminerals (MVMM; defined as a product containing ≥10 vitamins and/or minerals); and use of individual vitamins, minerals, and nonvitamin, nonmineral supplements. Data were analyzed overall and by population subgroup (including age, sex, race/ethnicity, and educational status), and were weighted to be nationally representative. Results A total of 37 958 adults were included in the study (weighted mean age, 46.4 years; women, 52.0% ), with an overall response rate of 74%. Overall, the use of supplements remained stable between 1999 and 2012, with 52% of US adults reporting use of any supplements in 2011-2012 (P for trend = .19). This trend varied by population subgroup. Use of MVMM decreased, with 37% reporting use of MVMM in 1999-2000 and 31% reporting use in 2011-2012 (difference, -5.7% [95% CI, -8.6% to -2.7%], P for trend < .001). Vitamin D supplementation from sources other than MVMM increased from 5.1% to 19% (difference, 14% [95% CI, 12% to 17%], P for trend  < .001) and use of fish oil supplements increased from 1.3% to 12% (difference, 11% [95% CI, 9.1% to 12%], P for trend < .001) over the study period, whereas use of a number of other supplements decreased. Conclusions and Relevance Among adults in the United States, overall use of dietary supplements remained stable from 1999-2012, use of MVMM decreased, and trends in use of individual supplements varied and were heterogeneous by population subgroups.

Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study

Objective To examine whether adherence to the Mediterranean diet was associated with longer telomere length, a biomarker of aging. Design Population based cohort study. Setting Nurses’ Health Study, an ongoing prospective cohort study of 121 700 nurses enrolled in 1976; in 1989-90 a subset of 32 825 women provided blood samples. Participants 4676 disease-free women from nested case-control studies within the Nurses’ Health Study with telomere length measured who also completed food frequency questionnaires. Main outcome measure Association between relative telomere lengths in peripheral blood leukocytes measured by quantitative real time polymerase chain reaction and Alternate Mediterranean Diet score calculated from self reported dietary data. Results Greater adherence to the Mediterranean diet was associated with longer telomeres after adjustment for potential confounders. Least squares mean telomere length z scores were −0.038 (SE 0.035) for the lowest Mediterranean diet score groups and 0.072 (0.030) for the highest group (P for trend=0.004). Conclusion In this large study, greater adherence to the Mediterranean diet was associated with longer telomeres. These results further support the benefits of adherence to the Mediterranean diet for promoting health and longevity.

A Model to Determine Colorectal Cancer Risk Using Common Genetic Susceptibility Loci

BACKGROUND & AIMS Risk for colorectal cancer (CRC) can be greatly reduced through screening. To aid in the development of screening strategies, we refined models designed to determine risk of CRC by incorporating information from common genetic susceptibility loci. METHODS By using data collected from more than 12,000 participants in 6 studies performed from 1990 through 2011 in the United States and Germany, we developed risk determination models based on sex, age, family history, genetic risk score (number of risk alleles carried at 27 validated common CRC susceptibility loci), and history of endoscopic examinations. The model was validated using data collected from approximately 1800 participants in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, conducted from 1993 through 2001 in the United States. RESULTS We identified a CRC genetic risk score that independently predicted which patients in the training set would develop CRC. Compared with determination of risk based only on family history, adding the genetic risk score increased the discriminatory accuracy from 0.51 to 0.59 (P = .0028) for men and from 0.52 to 0.56 (P = .14) for women. We calculated age- and sex-specific 10-year CRC absolute risk estimates based on the number of risk alleles, family history, and history of endoscopic examinations. A model that included a genetic risk score better determined the recommended starting age for screening in subjects with and without family histories of CRC. The starting age for high-risk men (family history of CRC and genetic risk score, 90%) was 42 years, and for low-risk men (no family history of CRC and genetic risk score, 10%) was 52 years. For men with no family history and a high genetic risk score (90%), the starting age would be 47 years; this is an intermediate value that is 5 years earlier than it would be for men with a genetic risk score of 10%. Similar trends were observed in women. CONCLUSIONS By incorporating information on CRC risk alleles, we created a model to determine the risk for CRC more accurately. This model might be used to develop screening and prevention strategies.

Mendelian randomization study of body mass index and colorectal cancer risk

Background: High body mass index (BMI) is consistently linked to increased risk of colorectal cancer for men, whereas the association is less clear for women. As risk estimates from observational studies may be biased and/or confounded, we conducted a Mendelian randomization study to estimate the causal association between BMI and colorectal cancer. Methods: We used data from 10,226 colorectal cancer cases and 10,286 controls of European ancestry. The Mendelian randomization analysis used a weighted genetic risk score, derived from 77 genome-wide association study–identified variants associated with higher BMI, as an instrumental variable (IV). We compared the IV odds ratio (IV-OR) with the OR obtained using a conventional covariate-adjusted analysis. Results: Individuals carrying greater numbers of BMI-increasing alleles had higher colorectal cancer risk [per weighted allele OR, 1.31; 95% confidence interval (CI), 1.10–1.57]. Our IV estimation results support the hypothesis that genetically influenced BMI is directly associated with risk for colorectal cancer (IV-OR per 5 kg/m2, 1.50; 95% CI, 1.13–2.01). In the sex-specific IV analyses higher BMI was associated with higher risk of colorectal cancer among women (IV-OR per 5 kg/m2, 1.82; 95% CI, 1.26–2.61). For men, genetically influenced BMI was not associated with colorectal cancer (IV-OR per 5 kg/m2, 1.18; 95% CI, 0.73–1.92). Conclusions: High BMI was associated with increased colorectal cancer risk for women. Whether abdominal obesity, rather than overall obesity, is a more important risk factor for men requires further investigation. Impact: Overall, conventional epidemiologic and Mendelian randomization studies suggest a strong association between obesity and the risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 24(7); 1024–31. ©2015 AACR.

Mendelian randomization study of height and risk of colorectal cancer

BACKGROUND For men and women, taller height is associated with increased risk of all cancers combined. For colorectal cancer (CRC), it is unclear whether the differential association of height by sex is real or is due to confounding or bias inherent in observational studies. We performed a Mendelian randomization study to examine the association between height and CRC risk. METHODS To minimize confounding and bias, we derived a weighted genetic risk score predicting height (using 696 genetic variants associated with height) in 10,226 CRC cases and 10,286 controls. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between height, genetically predicted height and CRC. RESULTS Using conventional methods, increased height (per 10-cm increment) was associated with increased CRC risk (OR = 1.08, 95% CI = 1.02-1.15). In sex-specific analyses, height was associated with CRC risk for women (OR = 1.15, 95% CI = 1.05-1.26), but not men (OR = 0.98, 95% CI = 0.92-1.05). Consistent with these results, carrying greater numbers of (weighted) height-increasing alleles (per 1-unit increase) was associated with higher CRC risk for women and men combined (OR = 1.07, 95% CI = 1.01-1.14) and for women (OR = 1.09, 95% CI =  .01-1.19). There was weaker evidence of an association for men (OR = 1.05, 95% CI = 0.96-1.15). CONCLUSION We provide evidence for a causal association between height and CRC for women. The CRC-height association for men remains unclear and warrants further investigation in other large studies.

Red Meat Intake, NAT2, and Risk of Colorectal Cancer: A Pooled Analysis of 11 Studies

Background: Red meat intake has been associated with risk of colorectal cancer, potentially mediated through heterocyclic amines. The metabolic efficiency of N-acetyltransferase 2 (NAT2) required for the metabolic activation of such amines is influenced by genetic variation. The interaction between red meat intake, NAT2 genotype, and colorectal cancer has been inconsistently reported. Methods: We used pooled individual-level data from the Colon Cancer Family Registry and the Genetics and Epidemiology of Colorectal Cancer Consortium. Red meat intake was collected by each study. We inferred NAT2 phenotype based on polymorphism at rs1495741, highly predictive of enzyme activity. Interaction was assessed using multiplicative interaction terms in multivariate-adjusted models. Results: From 11 studies, 8,290 colorectal cancer cases and 9,115 controls were included. The highest quartile of red meat intake was associated with increased risk of colorectal cancer compared with the lowest quartile [OR, 1.41; 95% confidence interval (CI), 1.29–1.55]. However, a significant association was observed only for studies with retrospective diet data, not for studies with diet prospectively assessed before cancer diagnosis. Combining all studies, high red meat intake was similarly associated with colorectal cancer in those with a rapid/intermediate NAT2 genotype (OR, 1.38; 95% CI, 1.20–1.59) as with a slow genotype (OR, 1.43; 95% CI, 1.28–1.61; P interaction = 0.9). Conclusion: We found that high red meat intake was associated with increased risk of colorectal cancer only from retrospective case–control studies and not modified by NAT2 enzyme activity. Impact: Our results suggest no interaction between NAT2 genotype and red meat intake in mediating risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 24(1); 198–205. ©2014 AACR.

Gene-environment interaction involving recently identified colorectal cancer susceptibility loci

Background: Genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) that are associated with risk of colorectal cancer. Prior research has evaluated the presence of gene–environment interaction involving the first 10 identified susceptibility loci, but little work has been conducted on interaction involving SNPs at recently identified susceptibility loci, including: rs10911251, rs6691170, rs6687758, rs11903757, rs10936599, rs647161, rs1321311, rs719725, rs1665650, rs3824999, rs7136702, rs11169552, rs59336, rs3217810, rs4925386, and rs2423279. Methods: Data on 9,160 cases and 9,280 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) and Colon Cancer Family Registry (CCFR) were used to evaluate the presence of interaction involving the above-listed SNPs and sex, body mass index (BMI), alcohol consumption, smoking, aspirin use, postmenopausal hormone (PMH) use, as well as intake of dietary calcium, dietary fiber, dietary folate, red meat, processed meat, fruit, and vegetables. Interaction was evaluated using a fixed effects meta-analysis of an efficient Empirical Bayes estimator, and permutation was used to account for multiple comparisons. Results: None of the permutation-adjusted P values reached statistical significance. Conclusions: The associations between recently identified genetic susceptibility loci and colorectal cancer are not strongly modified by sex, BMI, alcohol, smoking, aspirin, PMH use, and various dietary factors. Impact: Results suggest no evidence of strong gene–environment interactions involving the recently identified 16 susceptibility loci for colorectal cancer taken one at a time. Cancer Epidemiol Biomarkers Prev; 23(9); 1824–33. ©2014 AACR.

CYP24A1 variant modifies the association between use of oestrogen plus progestogen therapy and colorectal cancer risk

Background:Menopausal hormone therapy (MHT) use has been consistently associated with a decreased risk of colorectal cancer (CRC) in women. Our aim was to use a genome-wide gene–environment interaction analysis to identify genetic modifiers of CRC risk associated with use of MHT.Methods:We included 10 835 postmenopausal women (5419 cases and 5416 controls) from 10 studies. We evaluated use of any MHT, oestrogen-only (E-only) and combined oestrogen–progestogen (E+P) hormone preparations. To test for multiplicative interactions, we applied the empirical Bayes (EB) test as well as the Wald test in conventional case–control logistic regression as primary tests. The Cocktail test was used as secondary test.Results:The EB test identified a significant interaction between rs964293 at 20q13.2/CYP24A1 and E+P (interaction OR (95% CIs)=0.61 (0.52–0.72), P=4.8 × 10−9). The secondary analysis also identified this interaction (Cocktail test OR=0.64 (0.52–0.78), P=1.2 × 10−5 (alpha threshold=3.1 × 10−4). The ORs for association between E+P and CRC risk by rs964293 genotype were as follows: C/C, 0.96 (0.61–1.50); A/C, 0.61 (0.39–0.95) and A/A, 0.40 (0.22–0.73), respectively.Conclusions:Our results indicate that rs964293 modifies the association between E+P and CRC risk. The variant is located near CYP24A1, which encodes an enzyme involved in vitamin D metabolism. This novel finding offers additional insight into downstream pathways of CRC etiopathogenesis.

Whole-exome imputation of sequence variants identified two novel alleles associated with adult body height in African Americans

Adult body height is a quantitative trait for which genome-wide association studies (GWAS) have identified numerous loci, primarily in European populations. These loci, comprising common variants, explain <10% of the phenotypic variance in height. We searched for novel associations between height and common (minor allele frequency, MAF ≥5%) or infrequent (0.5% < MAF < 5%) variants across the exome in African Americans. Using a reference panel of 1692 African Americans and 471 Europeans from the National Heart, Lung, and Blood Institutes (NHLBI) Exome Sequencing Project (ESP), we imputed whole-exome sequence data into 13 719 African Americans with existing array-based GWAS data (discovery). Variants achieving a height-association threshold of P < 5E-06 in the imputed dataset were followed up in an independent sample of 1989 African Americans with whole-exome sequence data (replication). We used P < 2.5E-07 (=0.05/196 779 variants) to define statistically significant associations in meta-analyses combining the discovery and replication sets (N = 15 708). We discovered and replicated three independent loci for association: 5p13.3/C5orf22/rs17410035 (MAF = 0.10, β = 0.64 cm, P = 8.3E-08), 13q14.2/SPRYD7/rs114089985 (MAF = 0.03, β = 1.46 cm, P = 4.8E-10) and 17q23.3/GH2/rs2006123 (MAF = 0.30; β = 0.47 cm; P = 4.7E-09). Conditional analyses suggested 5p13.3 (C5orf22/rs17410035) and 13q14.2 (SPRYD7/rs114089985) may harbor novel height alleles independent of previous GWAS-identified variants (r(2) with GWAS loci <0.01); whereas 17q23.3/GH2/rs2006123 was correlated with GWAS-identified variants in European and African populations. Notably, 13q14.2/rs114089985 is infrequent in African Americans (MAF = 3%), extremely rare in European Americans (MAF = 0.03%), and monomorphic in Asian populations, suggesting it may be an African-American-specific height allele. Our findings demonstrate that whole-exome imputation of sequence variants can identify low-frequency variants and discover novel variants in non-European populations.

No evidence of gene-calcium interactions from genome-wide analysis of colorectal cancer risk

Background: Calcium intake may reduce risk of colorectal cancer, but the mechanisms remain unclear. Studies of interaction between calcium intake and SNPs in calcium-related pathways have yielded inconsistent results. Methods: To identify gene–calcium interactions, we tested interactions between approximately 2.7 million SNPs across the genome with self-reported calcium intake (from dietary or supplemental sources) in 9,006 colorectal cancer cases and 9,503 controls of European ancestry. To test for multiplicative interactions, we used multivariable logistic regression and defined statistical significance using the conventional genome-wide α = 5E−08. Results: After accounting for multiple comparisons, there were no statistically significant SNP interactions with total, dietary, or supplemental calcium intake. Conclusions: We found no evidence of SNP interactions with calcium intake for colorectal cancer risk in a large population of 18,509 individuals. Impact: These results suggest that in genome-wide analysis common genetic variants do not strongly modify the association between calcium intake and colorectal cancer in European populations. Cancer Epidemiol Biomarkers Prev; 23(12); 2971–6. ©2014 AACR.