Coffee drinking and colorectal cancer and its subsites: A pooled analysis of 8 cohort studies in Japan.

Coffee is a rich source of bioactive compounds that have potential anticarcinogenic effects. However, it remains unclear whether coffee drinking is associated with colorectal cancer. Also, despite different etiological factors involved in gut physiology, few studies have investigated this association by anatomical site of the lesion. To address these issues, this study examined the association between coffee drinking and colorectal cancer in a pooled analysis from 8 cohort studies conducted in Japan. Among 320,322 participants followed up for 4,503,274 person-years, 6,711 incident colorectal cancer cases were identified. Study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models and then pooled using the random effects model. Coffee drinking was not materially associated with colorectal cancer risk in men or women (pooled HR 0.92, 95% CI 0.82-1.03 in men and pooled HR 0.90, 95% CI 0.76-1.07 in women). Analysis by subsite showed a lower risk of colon cancer among female drinkers of ≥3 cups coffee/day (pooled HR 0.80, 95% CI 0.64-0.99). There was no such association in men. Coffee drinking was not associated with risk of rectal cancer in men or women. Results were virtually the same among never smokers except for an increased risk of rectal cancer associated with frequent coffee consumption. Coffee drinking may be associated with lower risk of colon cancer in Japanese women.

Coffee drinking and colorectal cancer risk: an evaluation based on a systematic review and meta-analysis among the Japanese population.

OBJECTIVE: It remains unclear whether coffee drinking is associated with colorectal cancer risk. We performed a systematic review and meta-analysis of epidemiologic studies on this issue among the Japanese population. METHODS: Original data were obtained from MEDLINE searches using PubMed or from searches of the 'Ichushi' database, complemented with manual searches. Meta-analysis was performed by using the random effects model to estimate the summary relative risk with 95% confidence interval according to the study design. The final judgment was made based on a consensus of the research group members with consideration for both epidemiological evidence and biological plausibility. RESULTS: We identified five cohort studies and nine case-control studies. Of these, one cohort study reported a strong inverse association (in women only), whereas three case-control studies reported a strong inverse association with colon or rectal cancer. In meta-analysis, high consumption of coffee was not appreciably associated with colorectal cancer risk among cohort studies, whereas it was associated with significantly lower risk of colorectal or colon cancer among case-control studies. The summary relative risk/odds ratio (95% confidence interval) for the highest versus lowest categories of coffee consumption was 0.95 (0.77-1.17) and 0.78 (0.65-0.95) for cohort and case-control studies, respectively. CONCLUSIONS: The evidence is insufficient to support that coffee drinking increases or decreases the risk of colorectal cancer among the Japanese population.

Dietary fiber intake and depressive symptoms in Japanese employees: The Furukawa Nutrition and Health Study.

OBJECTIVE: Dietary fiber may play a favorable role in mood through gut microbiota, but epidemiologic evidence linking mood to dietary fiber intake is scarce in free-living populations. We investigated cross-sectionally the associations of dietary intakes of total, soluble, insoluble, and sources of fiber with depressive symptoms among Japanese workers. METHODS: Participants were 1977 employees ages 19-69 y. Dietary intake was assessed via a validated, brief self-administered diet history questionnaire. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Logistic regression was used to estimate odds ratios of depressive symptoms adjusted for a range of dietary and non-dietary potential confounders. RESULTS: Dietary fiber intake from vegetables and fruits was significantly inversely associated with depressive symptoms. The multivariable-adjusted odds ratios (95% confidence intervals) for the lowest through the highest tertile of vegetable and fruit fiber were 1.00 (reference), 0.80 (0.60-1.05), and 0.65 (0.45-0.95), respectively (P for trend = 0.03). Dietary intake of total, soluble, insoluble, and cereal fiber was not associated with depressive symptoms. CONCLUSIONS: Higher dietary fiber intake from vegetables and fruits may be associated with lower likelihood of having depressive symptoms.