Objectives To investigate the association between intake of fish and n-3 polyunsaturated fatty acids (n-3 PUFA) and the risk of breast cancer and to evaluate the potential dose-response relation. Design Meta-analysis and systematic review of prospective cohort studies. Data sources PubMed and Embase up to December 2012 and references of retrieved relevant articles. Eligibility criteria for selecting studies Prospective cohort studies with relative risk and 95% confidence intervals for breast cancer according to fish intake, n-3 PUFA intake, or tissue biomarkers. Results Twenty six publications, including 20 905 cases of breast cancer and 883 585 participants from 21 independent prospective cohort studies were eligible. Eleven articles (13 323 breast cancer events and 687 770 participants) investigated fish intake, 17 articles investigated marine n-3 PUFA (16 178 breast cancer events and 527 392 participants), and 12 articles investigated alpha linolenic acid (14 284 breast cancer events and 405 592 participants). Marine n-3 PUFA was associated with 14% reduction of risk of breast cancer (relative risk for highest v lowest category 0.86 (95% confidence interval 0.78 to 0.94), I²=54), and the relative risk remained similar whether marine n-3 PUFA was measured as dietary intake (0.85, 0.76 to 0.96, I²=67%) or as tissue biomarkers (0.86, 0.71 to 1.03, I²=8%). Subgroup analyses also indicated that the inverse association between marine n-3 PUFA and risk was more evident in studies that did not adjust for body mass index (BMI) (0.74, 0.64 to 0.86, I²=0) than in studies that did adjust for BMI (0.90, 0.80 to 1.01, I²=63.2%). Dose-response analysis indicated that risk of breast cancer was reduced by 5% per 0.1g/day (0.95, 0.90 to 1.00, I²=52%) or 0.1% energy/day (0.95, 0.90 to 1.00, I²=79%) increment of dietary marine n-3 PUFA intake. No significant association was observed for fish intake or exposure to alpha linolenic acid. Conclusions Higher consumption of dietary marine n-3 PUFA is associated with a lower risk of breast cancer. The associations of fish and alpha linolenic acid intake with risk warrant further investigation of prospective cohort studies. These findings could have public health implications with regard to prevention of breast cancer through dietary and lifestyle interventions.

Background: Prospective cohort studies have examined mortality and overall cancer incidence among vegetarians, but the results have been inconclusive. Aims: The objective of the present meta-analysis was to investigate cardiovascular disease mortality and cancer incidence among vegetarians and nonvegetarians. Methods: Medline, EMBASE and Web Of Science databases were searched for cohort studies published from inception to September 2011. Studies were included if they contained the relative risk (RR) and corresponding 95% CI. Participants were from the UK, Germany, California, USA, the Netherlands and Japan. Results: Seven studies with a total of 124,706 participants were included in this analysis. All-cause mortality in vegetarians was 9% lower than in nonvegetarians (RR = 0.91; 95% CI, 0.66–1.16). The mortality from ischemic heart disease was significantly lower in vegetarians than in nonvegetarians (RR = 0.71; 95% CI, 0.56–0.87). We observed a 16% lower mortality from circulatory diseases (RR = 0.84; 95% CI, 0.54–1.14) and a 12% lower mortality from cerebrovascular disease (RR = 0.88; 95% CI, 0.70–1.06) in vegetarians compared with nonvegetarians. Vegetarians had a significantly lower cancer incidence than nonvegetarians (RR = 0.82; 95% CI, 0.67–0.97). Conclusions: Our results suggest that vegetarians have a significantly lower ischemic heart disease mortality (29%) and overall cancer incidence (18%) than nonvegetarians.

Background: Vegetarian diets exclude all animal flesh and are being widely adopted by an increasing number of people; however, effects on blood lipid concentrations remain unclear. This meta‐analysis aimed to quantitatively assess the overall effects of vegetarian diets on blood lipids. Methods and Results: We searched PubMed, Scopus, Embase, ISI Web of Knowledge, and the Cochrane Library through March 2015. Studies were included if they described the effectiveness of vegetarian diets on blood lipids (total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, and triglyceride). Weighted mean effect sizes were calculated for net changes by using a random‐effects model. We performed subgroup and univariate meta‐regression analyses to explore sources of heterogeneity. Eleven trials were included in the meta‐analysis. Vegetarian diets significantly lowered blood concentrations of total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, and non–high‐density lipoprotein cholesterol, and the pooled estimated changes were −0.36 mmol/L (95% CI −0.55 to −0.17; P <0.001), −0.34 mmol/L (95% CI −0.57 to −0.11; P <0.001), −0.10 mmol/L (95% CI −0.14 to −0.06; P <0.001), and −0.30 mmol/L (95% CI −0.50 to −0.10; P =0.04), respectively. Vegetarian diets did not significantly affect blood triglyceride concentrations, with a pooled estimated mean difference of 0.04 mmol/L (95% CI −0.05 to 0.13; P =0.40). Conclusions: This systematic review and meta‐analysis provides evidence that vegetarian diets effectively lower blood concentrations of total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, and non–high‐density lipoprotein cholesterol. Such diets could be a useful nonpharmaceutical means of managing dyslipidemia, especially hypercholesterolemia.

Objective: Results of studies on fish consumption and CHD mortality are inconsistent. The present updated meta-analysis was conducted to investigate the up-to-date pooling effects.Design: A random-effects model was used to pool the risk estimates. Generalized least-squares regression and restricted cubic splines were used to assess the possible dose–response relationship. Subgroup analyses were conducted to examine the sources of heterogeneity.Setting: PubMed and ISI Web of Science databases up to September 2010 were searched and secondary referencing qualified for inclusion in the study.Subjects: Seventeen cohorts with 315 812 participants and average follow-up period of 15·9 years were identified.Results: Compared with the lowest fish intake (5 servings/week). The dose–response analysis indicated that every 15 g/d increment of fish intake decreased the risk of CHD mortality by 6 % (RR = 0·94; 95 % CI 0·90, 0·98). The method of dietary assessment, gender and energy adjustment affected the results remarkably.Conclusions: Our results indicate that either low (1 serving/week) or moderate fish consumption (2–4 servings/week) has a significantly beneficial effect on the prevention of CHD mortality. High fish consumption (>5 servings/week) possesses only a marginally protective effect on CHD mortality, possibly due to the limited studies included in this group.