Many studies have reported that adherence to health promotion guidelines for diet, physical activity, and maintenance of healthy body weight may decrease cancer incidence and mortality. A systematic review was performed to examine associations between adherence to established cancer prevention guidelines for diet and physical activity and overall cancer incidence and mortality. PubMed, Google Scholar, and Cochrane Reviews databases were searched following the current recommendations of Preferred Reporting Items for Systematic Reviews and Meta-analysis Approach (PRISMA). Twelve studies met inclusion criteria for this review. High versus low adherence to established nutrition and physical activity cancer prevention guidelines was consistently and significantly associated with decreases of 10% to 61% in overall cancer colorectal cancer incidence in both men and women (27%-52%). Consistent significant reductions were also shown for breast cancer incidence (19-60%), endometrial cancer incidence (23-60%), and colorectal cancer incidence in both men and women (35-52%). Findings for lung cancer incidence were equivocal and no significant relationships were found between adherence and ovarian or prostate cancers. Adhering to cancer prevention guidelines for diet and physical activity is consistently associated with lower risks of overall cancer incidence and mortality, including for some site-specific cancers.

Over the past two decades, the question of whether vitamin D has a role in cancer incidence, progression, and mortality has been studied in detail. Colorectal, breast, and prostate cancers have been a particular area of focus; together, these three malignancies account for approximately 35% of cancer cases and 20% of cancer deaths in the United States, and as such are a major public health concern. Herein, we review and synthesize the epidemiological research regarding vitamin D, as measured by the biomarker 25-hydroxycholecalciferol [25(OH)D], and the incidence, progression, and mortality of these cancers. Overall, the results of observational studies of the relationship between 25(OH)D and colorectal cancer have revealed a consistent inverse association for incidence and mortality; while for breast cancer, results have generally demonstrated a relationship between higher 25(OH)D and lower risk for progression and mortality. In contrast, randomized, double-blind clinical trials conducted to date have generally failed to support these findings. For prostate cancer, there is no convincing evidence of an association between 25(OH)D and incidence, and inconsistent data for progression and mortality, though results of one open label clinical trial suggest that supplementation with 4000 IU/d of vitamin D3 may inhibit progression of the disease. Nonetheless, until the results of additional ongoing randomized, double-blind clinical trials are reported, it will be difficult to ascertain if vitamin D itself is related to a reduction in risk for some cancer endpoints, or whether high concentrations of the vitamin D biomarker 25(OH)D may instead serve as a marker for an overall beneficial risk factor profile.

Several studies have investigated the potential role of selenium (Se) in the development of type 2 diabetes (T2D) with disparate findings. We conducted a systematic review and meta-analysis to synthesize the evidence of any association between Se and T2D. PubMed, Embase, and Scopus were searched following the Preferred Reporting Items for Systematic Reviews and Meta-analysis Approach (PRISMA). Sixteen studies from 15 papers met inclusion criteria defined for this review. Of the 13 observational studies included, 8 demonstrated a statistically significant positive association between concentrations of Se and odds for T2D, with odds ratios (95% confidence intervals) ranging from 1.52 (1.01–2.28) to 7.64 (3.34–17.46), and a summary odds ratio (OR) (95% confidence interval (CI)) of 2.03 (1.51–2.72). In contrast, among randomized clinical trials (RCTs) of Se, a higher risk of T2D was not observed for those who received Se compared to a placebo (OR = 1.18, 95% CI 0.95–1.47). Taken together, the results for the relationship between Se and T2D differ between observational studies and randomized clinical trials (RCTs). It remains unclear whether these differences are the result of uncontrolled confounding in the observational studies, or whether there is a modest effect of Se on the risk for T2D that may vary by duration of exposure. Further investigations on the effects of Se on glucose metabolism are needed.

These findings show that higher plasma concentrations of selenium were significantly associated with prevalent T2D among participants in a selenium supplementation trial. Future work is needed to elucidate whether there are individual characteristics, such as blood concentrations of other antioxidants, which may influence this relation.

Study Objectives To evaluate the associations between sedentary time, total (total-PA), light (light-PA), moderate (MOD-PA), and vigorous (VIG-PA) physical activity with indices of sleep in postmenopausal women. Methods Baseline self-reported data from the Women’s Health Initiative Observational Study (n = 75 074) were used in this cross-sectional analysis. Total-PA, light-PA, MOD-PA, and VIG-PA were categorized by metabolic equivalents of the activity (MET-hour [hr]/week [wk]) and were estimated using validated questionnaires. Sedentary time was categorized by hr/day and was estimated via questionnaire. Logistic regression was used to examine the associations between these variables and short sleep (≤6 hr/night), long sleep (≥10 hr/night), poor sleep quality, and insomnia symptoms after adjustment for age, race, socioeconomic status, body mass index, health status, depressive symptoms, smoking status, alcohol use, hormone therapy, and comorbidities. Results Higher sedentary time (>11 hr/day) was associated with higher odds of short sleep (odds ratio [OR] = 1.80, 95% confidence interval [CI]: 1.72–1.88), poor sleep quality (OR = 1.85, 95% CI: 1.74–1.97), and insomnia symptoms (OR = 1.56, 95% CI: 1.49–1.64). Light-PA (>0 MET-hr/wk) was associated with lower odds of short sleep (OR = 0.96, 95% CI: 0.92–1.00), and higher amounts of total-PA (OR = 0.90, 95% CI: 0.84–0.97), light-PA (OR = 0.94, 95% CI: 0.89–1.00), and MOD-PA (OR = 0.91, 95% CI: 0.86–0.97) were associated with lower odds of poor sleep quality. Conclusions Our findings suggest that higher levels of light and moderate intensity physical activity are associated with better sleep quality, whereas higher amounts of sedentary time are associated with short sleep and lower quality sleep. Future studies should investigate the directionality of these associations and potential causal pathways.