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B-vitamins contribute to DNA synthesis, maintenance, and regulation. Few studies have examined associations of supplemental sources of B-vitamins with the incidence of upper gastrointestinal (GI) cancers [including gastric (GCA) and esophageal (ECA) cancers]; the only prior study to comprehensively examine such intakes reported potential elevated risks of ECA. We examined 159,401 postmenopausal women, ages 50–79 years at baseline, including 302 incident GCA and 183 incident ECA cases, over 19 years of follow-up within the Women's Health Initiative observational study and clinic trials. Adjusted Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for associations of supplemental B-vitamins [riboflavin (B2), pyridoxine (B6), folic acid (B9), or cobalamin (B12)] with GCA and ECA risk, respectively. Although HRs were generally below 1.0, we observed no statistically significant associations between supplemental intakes of any of the evaluated B-vitamins with the risk of GCA or ECA. As the first prospective study to comprehensively assess these associations, our findings do not corroborate prior research indicating potential harm from supplemental B-vitamin intake for upper GI cancer risk. This study adds evidence that supplemental intakes of B-vitamins may be used by postmenopausal women without regard to their relationship with upper GI cancer risk. [ABSTRACT FROM AUTHOR]

Proton pump inhibitors (PPIs) have off-target activity on fatty acid synthase (FASN), a critical enzyme in energy balance and cancer growth. We evaluated risk of common obesity-related cancers: breast, colorectal (CRC), and endometrial, with use of PPI and histamine-2 receptor antagonists (H2RA) in 124,931 postmenopausal women enrolled in the Women's Health Initiative. Incident cancer cases were physician-adjudicated. Cox proportional hazards models were used to estimate multivariable hazard ratios (HR) and 95% confidence intervals (CI) for cancer incidence after year 3. There were 7956 PPI ever users and 9398 H2RA only users. Ever use of either PPI or H2RA was not associated with risk of breast cancer (n = 9186) nor risk of endometrial cancer (n = 1231). The risk of CRC (n = 2280) was significantly lower in PPI users (HR = 0.75, 95% CI = 0.61–0.92), but not in H2RA users (HR = 1.13, 95% CI = 0.97–1.31). The association of PPI use with CRC was apparent regardless of BMI or NSAID use, and was stronger with longer PPI duration (p = 0.006) and potency (p = 0.005). The findings that PPI use, but not H2RA use, demonstrate an inverse dose-response relationship with risk of CRC is consistent with preclinical data showing FASN inhibition prevents colon cancer progression and supports a role of PPI in CRC prevention. [ABSTRACT FROM AUTHOR]

Evidence-based guidelines for cancer survivorship do not recommend dietary supplementation, yet older cancer survivors report high prevalence of dietary supplement use, specifically multivitamin (MVM), calcium, and vitamin D. Female cancer survivors (≥65 years) who were ≤5 years post-cancer diagnosis completed questionnaires assessing health-related quality of life (HRQoL), diet quality, and supplement intake. Intakes of MVM, calcium, and vitamin D supplementation were 61.4%, 76.9%, and 35.3%, respectively. Women who used MVM supplements had significantly higher dietary quality mean scores for total vegetables (4.5 ± 0.9 to 4.1 ± 1.1), greens and beans (4.1 ± 1.3 to 3.6 ± 1.6), whole fruit (4.7 ± 0.8 to 4.3 ± 1.3), and whole grains (2.9 ± 1.8 to 2.3 ± 1.6) than those who did not use these supplements. After controlling for demographic and clinical variables, the odds of MVM use was 1.07 times greater among those women who had higher total HEI scores. Participants with lower HRQoL were 4% more likely to take an MVM. Understanding the prevalence of supplementation, associations with diet quality, and perceived benefits of supplementation may help healthcare providers in educating survivors and promoting adherence to the evidence-based guidelines. [ABSTRACT FROM AUTHOR]

Research suggests that high intake of supplemental vitamin B12 may be associated with increased risk of cancer, with some evidence that this association may vary by gender and smoking status. This investigation evaluates if similar patterns in association are observed for data for 11,757 adults from the National Health and Nutrition Examination Survey (1999-2006). Survey-weighted multivariable-adjusted linear regression was used to evaluate the association between regular B12 supplement use and log-transformed serum B12 levels. Persons taking vitamin B12 through a multivitamin/multimineral (MVMM) had a median supplemental intake of 12 mcg/day (Q1: 6, Q3: 25), compared to 100 mcg/day (Q1: 22, Q3: 500) for persons reporting supplemental B12 intake through a MVMM-exclusive source. MVMM users had a geometric mean serum B12 26% (95% CI: 23%-30%) higher than nonusers, whereas MVMM-exclusive users' geometric mean was 61% (95% CI: 53%-70%) higher than nonusers (p-trend < 0.001). Although a positive trend (p-trend < 0.001) was observed for both men and women, the association was stronger among women (p-interaction < 0.001). No interaction was observed for smoking status (p-interaction = 0.45). B12 supplementation is associated with higher levels of serum B12, with significant interaction by gender but not smoking. Further work is needed to better understand the interplay of B12 and gender. [ABSTRACT FROM AUTHOR]