Calcium plays a major role in apoptosis, cell proliferation, and various cellular mechanisms. It is also essential for the function of the pancreas. However, the association between calcium intake and pancreatic cancer is not clear. This study aims to clarify the links between calcium intake and pancreatic cancer risk using a systematic review and meta-analysis of observational studies. PubMed, Web of Science, Scopus, and Google Scholar were searched for eligible articles published through 31 August 2023. Case-control and cohort studies reporting the association between dietary and/or supplemental calcium intake and risk of pancreatic cancer using relative risk (RR), hazard ratio (HR), or odds ratio (OR) with 95% confidence interval (CI) were included. Meta-analysis using a random effect model was used to estimate the significance of the association. Eight studies were included. An inverse association between total calcium intake (dietary and supplement) and pancreatic cancer risk (RR, 0.83; 95% CI, 0.72–0.97; I2 = 0%) was observed. However, the association between dietary calcium intake alone and pancreatic cancer risk did not reach a statistically significant level (RR, 0.91; 95% CI, 0.78–1.06; I2 = 48%). Higher total calcium intake may reduce the risk of pancreatic cancer but the difference between sources of calcium (dietary vs. supplementation) requires further investigation. Also, due to the heterogeneity between the articles, the results of this study should be interpreted with caution.
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Despite mounting evidence that dietary polyphenols might have a protective role against the risk of breast cancer (BC), few studies have assessed the relationship between intake of polyphenol classes and subclasses with BC. Thus, we examined the relationship between dietary polyphenol classes and individual polyphenol subclasses and the risk of BC. Overall, 134 newly diagnosed BC patients and 267 healthy hospitalized controls were studied. Dietary intake was assessed using a validated 168-item food frequency questionnaire (FFQ). To estimate dietary intake of polyphenols, polyphenol content (flavonoids, lignans, stilbenes and phenolic acids) of 80 food items were derived from an updated version of the phenol explorer database containing information on the effects of food processing on polyphenol content. The dietary polyphenol intake was calculated by matching the subjects' food consumption data with our polyphenol content database. Multivariate logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Controls had higher intake of total polyphenol (marginally significant; p = 0.07), hydroxycinnamic acid (marginally significant; p = 0.05) and lignan (p = 0.01). After adjusting for potential confounders, high consumption of lignans (highest vs. lowest tertile: OR, 0.51; 95% CI, 0.26–0.97; p for trend = 0.04) associated with decreased risk of BC. There was no significant relationship between intake of other polyphenols and risk of BC. Our findings suggest that high lignan intake is associated with a reduced risk of BC.
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