Numbers of epidemiologic studies assessing soy consumption and risk of breast cancer have yielded inconsistent results. We aimed to examine the association between soy isoflavones consumption and risk of breast cancer incidence or recurrence, by conducting a meta-analysis of prospective studies. We searched for all relevant studies with a prospective design indexed in PUBMED through September 1st, 2010. Summary relative risks (RR) were calculated using fixed- or random-effects models. Pre-specified stratified analyses and dose-response analysis were also performed. We identified 4 studies of breast cancer recurrence and 14 studies of breast cancer incidence. Soy isoflavones consumption was inversely associated with risk of breast cancer incidence (RR = 0.89, 95% CI: 0.79-0.99). However, the protective effect of soy was only observed among studies conducted in Asian populations (RR = 0.76, 95% CI: 0.65-0.86) but not in Western populations (RR = 0.97, 95% CI: 0.87-1.06). Soy isoflavones intake was also inversely associated with risk of breast cancer recurrence (RR = 0.84, 95% CI: 0.70-0.99). Stratified analyses suggested that menopausal status may be an important effect modifier in these associations. We failed to identify a dose-response relationship between total isoflavones intake and risk of breast cancer incidence. Our study suggests soy isoflavones intake is associated with a significant reduced risk of breast cancer incidence in Asian populations, but not in Western populations. Further studies are warranted to confirm the finding of an inverse association of soy consumption with risk of breast cancer recurrence.

No abstract

OBJECTIVEEmerging epidemiological evidence suggests that higher magnesium intake may reduce diabetes incidence. We aimed to examine the association between magnesium intake and risk of type 2 diabetes by conducting a meta-analysis of prospective cohort studies.RESEARCH DESIGN AND METHODSWe conducted a PubMed database search through January 2011 to identify prospective cohort studies of magnesium intake and risk of type 2 diabetes. Reference lists of retrieved articles were also reviewed. A random-effects model was used to compute the summary risk estimates.RESULTSMeta-analysis of 13 prospective cohort studies involving 536,318 participants and 24,516 cases detected a significant inverse association between magnesium intake and risk of type 2 diabetes (relative risk [RR] 0.78 [95% CI 0.73–0.84]). This association was not substantially modified by geographic region, follow-up length, sex, or family history of type 2 diabetes. A significant inverse association was observed in overweight (BMI ≥25 kg/m2) but not in normal-weight individuals (BMI <25 kg/m2), although test for interaction was not statistically significant (Pinteraction = 0.13). In the dose-response analysis, the summary RR of type 2 diabetes for every 100 mg/day increment in magnesium intake was 0.86 (95% CI 0.82–0.89). Sensitivity analyses restricted to studies with adjustment for cereal fiber intake yielded similar results. Little evidence of publication bias was observed.CONCLUSIONSThis meta-analysis provides further evidence supporting that magnesium intake is significantly inversely associated with risk of type 2 diabetes in a dose-response manner.

Vitamin D is suggested to have protective effects against type 1 diabetes. However, the results from observational studies have been inconsistent. We aimed to examine their association by conducting a meta-analysis of observational studies. Multiple databases were searched in June 2013 to identify relevant studies including both case-control and cohort studies. Either a fixed- or random-effects model was used to calculate the pooled risk estimate. We identified eight studies (two cohort studies and six case-control studies) on vitamin D intake during early life and three studies (two cohort studies and one case-control study) on maternal vitamin D intake during pregnancy. The pooled odds ratio for type 1 diabetes comparing vitamin D supplementation with non-supplementation during early life was 0.71 (95% confidence interval [CI], 0.51–0.98). Similar results were observed in the case-control subgroup analysis but not in the cohort subgroup analysis. The pooled odds ratio with maternal intake of vitamin D during pregnancy was 0.95 (95% CI, 0.66–1.36). In conclusion, vitamin D intake during early life may be associated with a reduced risk of type 1 diabetes. However, there was not enough evidence for an association between maternal intake of vitamin D and risk of type 1 diabetes in the offspring.

To date, the relationship between obesity and the incidence of lung cancer remains unclear and inconclusive. Thus, we conducted a meta-analysis of published studies to provide a quantitative evaluation of this association. Relevant studies were identified through PubMed and EMBASE databases from 1966 to December 2011, as well as through the reference lists of retrieved articles. A total of 31 articles were included in this meta-analysis. Overall, excess body weight (body mass index, BMI 25 kg/m 2 ) was inversely associated with lung cancer incidence (relative risk, RR 5 0.79; 95% confidence interval, CI:0.73-0.85) compared with normal weight (BMI 5 18.5-24.9 kg/m 2 ). The association did not change with stratification by sex, study population, study design, and BMI measurement method. However, when stratified by smoking status, the inverse association between excess body weight and lung cancer incidence in current (RR 5 0.63, 95% CI: 0.57-0.70) and former (RR 5 0.73, 95% CI: 0.58-0.91) smokers was strengthened. In non-smokers, the association was also statistically significant (RR 5 0.83, 95% CI: 0.70-0.98), although the link was weakened to some extent. The stratified analyses also showed that excess body weight was inversely associated with squamous cell carcinoma (RR 5 0.68, 95% CI: 0.58-0.80) and adenocarcinoma (RR 5 0.79, 95% CI: 0.65-0.96). No statistically significant link was found between excess body weight and small cell carcinoma (RR 5 0.99, 95% CI: 0.66-1.48). The results of this meta-analysis indicate that overweight and obesity are protective factors against lung cancer, especially in current and former smokers.

High-protein diets are popular for weight management, but the health effects of such diets in diabetic persons are inconclusive. The aim of the present meta-analysis was to examine the effects of high-protein diets on body weight and metabolic risk factors in patients with type 2 diabetes. We searched the PubMed and Cochrane Library databases for relevant randomised trials up to August 2012. Either a fixed-or a random-effects model was used to combine the net changes in each outcome from baseline to the end of the intervention. Overall, nine trials including a total of 418 diabetic patients met our inclusion criteria. The study duration ranged from 4 to 24 weeks. The actual intake of dietary protein ranged from 25 to 32 % of total energy in the intervention groups and from 15 to 20 % in the control groups. Compared with the control diets, high-protein diets resulted in more weight loss (pooled mean difference: 2 2·08, 95 % CI 23·25, 2 0·90 kg). High-protein diets significantly decreased glycated Hb A 1C (HbA 1C ) levels by 0·52 (95 % CI 20·90, 2 0·14) %, but did not affect the fasting blood glucose levels. There were no differences in lipid profiles. The pooled net changes in systolic and diastolic blood pressure were 23·13 (95 % CI 26·58, 0·32) mmHg and 21·86 (95 % CI 24·26, 0·56) mmHg, respectively. However, two studies reported a large influence on weight loss and HbA 1C levels, respectively. In summary, high-protein diets (within 6 months) may have some beneficial effects on weight loss, HbA 1C levels and blood pressure in patients with type 2 diabetes. However, further investigations are still required to draw a conclusion.

Background and Purpose-A history of depression may be associated with an increased risk of stroke. We aimed to determine the association between depression and risk of stroke by performing a meta-analysis of prospective studies. Methods-Relevant studies were identified by a PubMed database search through May 2011 without restrictions and by reviewing reference lists of obtained articles. Community-based or population-based prospective studies that reported relative risk estimates with 95% confidence intervals for the association between depression and stroke were selected. Studies that enrolled participants with preexisting stroke at baseline were excluded. A random-effects model was used to compute the pooled risk estimate. Results-Random-effects meta-analysis of 17 prospective studies involving 206 641 participants and 6086 cases demonstrated a significant positive association between depression and subsequent risk of stroke (pooled relative risk, 1.34; 95% confidence interval, 1.17-1.54) after adjustment for potential confounding factors. The associations were similar between men and women. Potential publication bias may exist, but correction for this bias using a formal statistical method did not materially alter the combined risk estimate. Conclusions-Depression significantly increased the risk of development of stroke, and this increase was probably independent of other risk factors, including hypertension and diabetes. (Stroke. 2012;43:32-37.)

No abstract