title: Association between dietary nitrate and nitrite intake and sitespecific cancer risk: evidence from observational studies.
abstract: Epidemiological studies have reported inconsistent findings on the association between dietary nitrate and nitrite intake and cancer risk. We performed a meta-analysis of epidemiological studies to summarize available evidence on the association between dietary nitrate and nitrite intake and cancer risk from published prospective and case-control studies. PubMed database was searched to identify eligible publications through April 30th, 2016. Study-specific relative risks (RRs) with corresponding 95% confidence interval (CI) from individual studies were pooled by using random- or fixed- model, and heterogeneity and publication bias analyses were conducted. Data from 62 observational studies, 49 studies for nitrates and 51 studies for nitrites, including a total of 60,627 cancer cases were analyzed. Comparing the highest vs. lowest levels, dietary nitrate intake was inversely associated with gastric cancer risk (RR = 0.78; 95%CI = 0.67-0.91) with moderate heterogeneity (I2 = 42.3%). In contrast, dietary nitrite intake was positively associated with adult glioma and thyroid cancer risk with pooled RR of 1.21 (95%CI = 1.03-1.42) and 1.52 (95%CI = 1.12-2.05), respectively. No significant associations were found between dietary nitrate/nitrite and cancers of the breast, bladder, colorectal, esophagus, renal cell, non-Hodgkin lymphoma, ovarian, and pancreas. The present meta-analysis provided modest evidence that positive associations of dietary nitrate and negative associations of dietary nitrite with certain cancers.
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Xie
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Mo
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Hui-Xun
authors.initials: HX
authors.lastname: Jia
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Liang
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Clinical Statistics Center, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.|Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Ji
authors.initials: J
authors.lastname: Zhu
mesh_terms: D000465:Algorithms; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000175:diagnosis* / Q000517:prevention & control*; D009566:Nitrates / Q000737:chemistry*; D009573:Nitrites / Q000737:chemistry*; D064887:Observational Studies as Topic; D012306:Risk
chemical_list: D009566:Nitrates; D009573:Nitrites
keywords: cancer; meta-analysis; nitrate; nitrite; risk