Dairy Food, Calcium, and Risk of Cancer in the NIH-AARP Diet and Health Study

Abstract

Background Dairy food and calcium have been hypothesized to play roles that differ among individual cancer sites, but the evidence has been limited and inconsistent. Moreover, the effect of dairy food and calcium on cancer in total is unclear. Methods Dairy food and calcium in relation to total cancer as well as cancer at individual sites were examined in the NIH-AARP Diet and Health Study. Intakes of dairy food and calcium from foods and supplements were assessed with a food frequency questionnaire. Incident cancer cases were identified through linkage with state cancer registries. Cox proportional hazard model was used to estimate relative risks (RRs) and tow-sided 95% confidence intervals (CI). Results During average of 7 years of follow-up, we identified 36,965 and 16,605 cancer cases in men and women, respectively. Calcium intake was not related to total cancer in men, but was non-linearly associated with total cancer in women: risk decreased up to approximately 1,300 mg/day, above which no further risk reduction was observed. In both men and women, dairy food and calcium were inversely associated with cancers of the digestive system (multivariate RR for the highest quintile of total calcium vs. the lowest = 0.84, 95% CI: 0.77–0.92 in men and 0.77, 95% CI: 0.69–0.91 in women). Decreased risk was particularly pronounced with colorectal cancer. Supplemental calcium was also inversely associated with colorectal cancer risk. Conclusions Our study suggests that calcium intake is associated with lower risk of total cancer and cancers of the digestive system, especially colorectal cancer.

Mechanisms Linking Colorectal Cancer to the Consumption of (Processed) Red Meat: A Review

“…Interestingly, high calcium contents of experimental diets have been shown to reduce CRC risk associated with (processed) red meat intake both in animals (Sesink et al, 2001) and in humans , probably through interference with the effects of heme. In spite of the presence of inflammatory Neu5Gc, the significantly higher calcium levels in processed dairy products (»500 mg/100g) compared to processed red meat (»10 mg/ 100 g) (NUBEL, 2013) may thus account for the protective effects of dairy foods as reported earlier (Park et al, 2009;Pala et al, 2011). Anyway, the near absence of Neu5Gc in poultry and fish could provide an explanation for the "white meat controversy" and its importance justifies further research efforts.…”

Calcium intake and breast cancer risk: meta-analysis of prospective cohort studies

“…1. We included eleven studies (11)(12)(13)(15)(16)(17)(18)(19)(35)(36)(37) that fully met our inclusion criteria for this meta-analysis. The characteristics of the included studies are summarised in Table 1.…”

“…Their results became statistically non-significant after correcting for publication bias. The meta-analysis was followed by several subsequent prospective studies (15)(16)(17)(18)(19) that also focused on the same topic, but their findings continued to be inconsistent. To clarify the association between Ca intake and risk of breast cancer, we performed an updated meta-analysis of prospective studies.…”

Dietary supplement use and colorectal cancer risk: A systematic review and meta‐analyses of prospective cohort studies

“…51 The 52 before including the study in the overall analysis. For studies that reported results for men and women separately, 33,40,43 and for studies that showed separate results for colon and rectal cancer, 35,49 we used fixed effect meta-analyses to obtain an overall estimate for overall gender and for colorectal cancer, respectively.…”

“…We included eight studies in "use-no use" meta-analysis, 34,37,40,[42][43][44][45][46] and six studies in "highest-lowest" meta-analysis. 34,37,40,[42][43][44] A statistically significantly decreased risk for colorectal cancer was observed in "useno use" ( Table 2, 2 5 0.0%, p 5 0.82) when we stratified for cancer site in "use-no use" metaanalysis, while heterogeneity was reduced for colorectal cancer (RR 5 0.91; 95% CI: 0.86,0.96), I 2 5 26.9%, p 5 0.21). "Dose-response" meta-analysis was based on six studies.…”