Although red meat and processed meat are well-established risk factors of colorectal cancer (CRC), the mechanisms underlying this association are less clear. Heme iron, abundant in red and processed meats, is one plausible etiologic factor. In addition, calcium, a well-established independent protective factor against CRC, may prevent heme-induced colorectal carcinogenesis by binding to heme iron in the gut. We prospectively examined the association between heme iron and CRC risk and whether these associations differed by calcium intake in the Nurses’ Health Study, Nurses’ Health Study II and Health Professionals Follow-Up Study. We used Cox proportional hazards regression analyses to calculate cohort-specific hazard ratios (HRs) and pooled results using a fixed-effect model. We analyzed data from 211,851 participants and documented 2983 incident CRC cases during up to 36 years of follow-up. Comparing the highest to lowest quintile, the pooled multivariable HRs (95% CIs) for CRC were 1.03 (0.91, 1.17) for total heme iron intake, 1.02 (0.91, 1.16) for heme iron from red and processed meat, and 1.02 (0.90, 1.15) for heme iron from non-red and non-processed meat sources. Total heme iron intake, heme iron from red and processed meat, and heme iron from non-red meat and non-processed meat sources were largely not associated with CRC risk. Moreover, the association between heme iron and CRC did not appear to differ by calcium status. Overall, our study does not support a strong role of heme iron intake in CRC risk and suggests that the protective association of calcium intake on CRC risk does not depend on heme iron.
Waverly Shi, Peilu Wang, E. Giovannucci· Cancer Causes and Control· 0 citations
BACKGROUND
Type 2 diabetes (T2D) is associated with an increased risk of premature death. Diet may influence long-term health outcomes among individuals with T2D, but prospective evidence on dietary patterns and mortality remains limited.
OBJECTIVES
To prospectively examine associations of eleven pre-defined or empirically-developed dietary patterns with all-cause and cause-specific mortality (e.g., cardiovascular disease [CVD] and cancer) among U.S. individuals with T2D.
METHODS
We included 7,795 participants with incident T2D in the Nurses' Health Study (1984-2016) and Health Professionals Follow-Up Study (1986-2020), who were free of CVD and cancer at diagnosis. Diet was assessed using a validated food frequency questionnaire and updated every four years. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs.
RESULTS
Over 24 years of follow-up, 3,509 deaths were confirmed, including 1,079 from CVD and 649 from cancer. Adherence to healthy dietary patterns after diagnosis (comparing the 90th with the 10th percentile of dietary pattern scores) was consistently associated with lower all-cause mortality, with multivariable-adjusted HRs ranging from 0.78 (95% CI: 0.71, 0.85) for the Planetary Health Diet to 0.92 (95% CI: 0.84, 1.01) for the Dietary Approaches to Stop Hypertension. Furthermore, greater improvements in dietary pattern adherence from pre- to post-diagnosis (comparing the 90th with the 10th percentile of change scores) were also associated with lower all-cause mortality, with HRs (95% CI) ranging from 0.63 (0.58, 0.70) to 0.92 (0.85, 1.01). A similar pattern of inverse associations with CVD mortality was also observed for these dietary scores. Additionally, the reversed Empirical Dietary Index for Hyperinsulinemia was specifically associated with lower cancer mortality.
CONCLUSIONS
Adherence to healthy dietary patterns is universally associated with better survival in individuals with T2D. These findings suggest the importance of consuming high-quality diets in the prevention of premature deaths among individuals with T2D.
Zi-Xin Qiu, Gang Liu, Binkai Liu et al.· American Journal of Clinical...· 0 citations
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