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), I 2 =54), and the relative risk remained similar whether marine n-3 PUFA was measured as dietary intake (0.85, 0.76 to 0.96, I 2 =67%) or as tissue biomarkers (0.86, 0.71 to 1.03, I 2 =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, I 2 =0) than in studies that did adjust for BMI (0.90, 0.80 to 1.01, I 2 =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, I 2 =52%) or 0.1% energy/day (0.95, 0.90 to 1.00, I 2 =79%) increment of dietary marine n-3 PUFA intake. No significant association was observed for fish intake or exposure to alpha linolenic acid. ConclusionsHigher 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.

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 (,1 serving/month or 1-3 servings/ month), the pooled relative risk (RR) of fish intake on CHD mortality was 0?84 (95 % CI 0?75, 0?95) for low fish intake (1 serving/week), 0?79 (95 % CI 0?67, 0?92) for moderate fish intake (2-4 servings/week) and 0?83 (95 % CI 0?68, 1?01) for high 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 5 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.

ObjectiveAlthough Hashimoto's thyroiditis is associated with cardiovascular disease and malignancy, the global status of Hashimoto's thyroiditis is not well characterized across regions. Our objective was to evaluate the prevalence and trends of Hashimoto's thyroiditis in adults in regions with different economic income levels around the world.MethodsFor this systematic review and meta-analysis, we searched PubMed, Embase, MEDLINE, Scopus, and Web of Science databases, and 48 random-effects representative studies from the inception to June 2022 were included without language restrictions to obtain the overall prevalence of Hashimoto's thyroiditis in adults worldwide. In addition, we stratified by time of publication, geographic region, economic level of the region of residence, gender, diagnostic method, etc.ResultsA total of 11,399 studies were retrieved, of which 48 met the research criteria: 20 from Europe, 16 from Asia, five from South America, three from North America, and three from Africa. Furthermore, there are two projects involving 19 countries and 22,680,155 participants. The prevalence of Hashimoto's thyroiditis was 7.5 (95%CI 5.7–9.6%), while in the low-middle-income group the prevalence was 11.4 (95%CI 2.5–25.2%). Similarly, the prevalence was 5.6 (95%Cl 3.9–7.4%) in the upper-middle-income group, and in the high-income group, the prevalence was 8.4 (95%Cl 5.6–11.8). The prevalence of Hashimoto's varied by geographic region: Africa (14.2 [95% CI 2.5–32.9%]), Oceania (11.0% [95% CI 7.8–14.7%]), South America and Europe 8.0, 7.8% (95% Cl 0.0–29.5%) in North America, and 5.8 (95% Cl 2.8–9.9%) in Asia. Although our investigator heterogeneity was high (I2), our results using a sensitivity analysis showed robustness and reliability of the findings. People living in low-middle-income areas are more likely to develop Hashimoto's thyroiditis, while the group in high-income areas are more likely to develop Hashimoto's thyroiditis than people in upper-middle-income areas, and women's risk is about four times higher than men's.ConclusionsGlobal Hashimoto's thyroiditis patients are about four times as many as males, and there are discrepancies in the regions with different economic levels. In low-middle-income areas with a higher prevalence of Hashimoto's thyroiditis, especially countries in Africa, therefore local health departments should take strategic measures to prevent, detect, and treat Hashimoto's thyroiditis. At the same time, the hidden medical burden other diseases caused by Hashimoto's thyroiditis should also be done well.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier: CRD 42022339839.