Pengcheng Xun

Magnesium Intake and Risk of Type 2 Diabetes Meta-analysis of prospective cohort studies

OBJECTIVE Emerging 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 METHODS We 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. RESULTS Meta-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. CONCLUSIONS This meta-analysis provides further evidence supporting that magnesium intake is significantly inversely associated with risk of type 2 diabetes in a dose-response manner.

Egg consumption in relation to risk of cardiovascular disease and diabetes: a systematic review and meta-analysis

BACKGROUND The associations of egg consumption with cardiovascular disease (CVD) and diabetes are still unclear. OBJECTIVE We aimed to quantitatively summarize the literature on egg consumption and risk of CVD, cardiac mortality, and type 2 diabetes by conducting a meta-analysis of prospective cohort studies. DESIGN A systematic literature review was conducted for published studies in PubMed and EMBASE through March 2012. Additional information was retrieved through Google or a hand review of the reference from relevant articles. Studies were included if they had a prospective study design, were published in English-language journals, and provided HRs and 95% CIs for the associations of interest. Data were independently extracted by 2 investigators, and the weighted HRs and 95% CIs for the associations of interest were estimated by using a random-effects model. RESULTS A total of 22 independent cohorts from 16 studies were identified, including participants ranging in number from 1600 to 90,735 and in follow-up time from 5.8 to 20.0 y. Comparison of the highest category (≥1 egg/d) of egg consumption with the lowest (<1 egg/wk or never) resulted in a pooled HR (95% CI) of 0.96 (0.88, 1.05) for overall CVD, 0.97 (0.86, 1.09) for ischemic heart disease, 0.93 (0.81, 1.07) for stroke, 0.98 (0.77, 1.24) for ischemic heart disease mortality, 0.92 (0.56, 1.50) for stroke mortality, and 1.42 (1.09, 1.86) for type 2 diabetes. Of the studies conducted in diabetic patients, the pooled HR (95% CI) was 1.69 (1.09, 2.62) for overall CVD. CONCLUSIONS This meta-analysis suggests that egg consumption is not associated with the risk of CVD and cardiac mortality in the general population. However, egg consumption may be associated with an increased incidence of type 2 diabetes among the general population and CVD comorbidity among diabetic patients.

Magnesium Intake in Relation to Systemic Inflammation, Insulin Resistance, and the Incidence of Diabetes

OBJECTIVE To investigate the long-term associations of magnesium intake with incidence of diabetes, systemic inflammation, and insulin resistance among young American adults. RESEARCH DESIGN AND METHODS A total of 4,497 Americans, aged 18–30 years, who had no diabetes at baseline, were prospectively examined for incident diabetes based on quintiles of magnesium intake. We also investigated the associations between magnesium intake and inflammatory markers, i.e., high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and fibrinogen, and the homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS During the 20-year follow-up, 330 incident cases of diabetes were identified. Magnesium intake was inversely associated with incidence of diabetes after adjustment for potential confounders. The multivariable-adjusted hazard ratio of diabetes for participants in the highest quintile of magnesium intake was 0.53 (95% CI, 0.32–0.86; Ptrend < 0.01) compared with those in the lowest quintile. Consistently, magnesium intake was significantly inversely associated with hs-CRP, IL-6, fibrinogen, and HOMA-IR, and serum magnesium levels were inversely correlated with hs-CRP and HOMA-IR. CONCLUSIONS Magnesium intake was inversely longitudinally associated with incidence of diabetes in young American adults. This inverse association may be explained, at least in part, by the inverse correlations of magnesium intake with systemic inflammation and insulin resistance.

Higher Branched-Chain Amino Acid Intake Is Associated with a Lower Prevalence of Being Overweight or Obese in Middle-Aged East Asian and Western Adults

Beneficial effects on body weight of supplementation with BCAA, including leucine, isoleucine, and valine, have been observed in animal and human studies. However, population-based studies on dietary BCAA intake and body weight are lacking. The objective of this study was to examine the association between dietary BCAA intake and risk of overweight status/obesity among multi-ethnic populations. The International Study of Macro-/Micronutrients and Blood Pressure is a cross-sectional epidemiological investigation in China, Japan, the UK, and the US. The study cohort included 4429 men and women ages 40-59 y who were free of diabetes. Diet was assessed by 4 multi-pass 24-h recalls; data on nutrients including BCAA were derived from country-specific food tables. Overweight status and obesity were defined as BMI ≥ 25 and BMI ≥ 30 kg/m(2), respectively. Multivariable-adjusted OR of overweight status/obesity and 95% CI by quartiles of BCAA intake were estimated by logistic regression. Mean BCAA intake was 2.6 ± 0.6% energy; intake was significantly lower among Chinese participants and similar among participants from the other 3 countries. Compared with those in the first quartile, the multivariable-adjusted OR (95% CI) of overweight status from the 2nd to 4th quartiles of BCAA intake were 0.97 (0.80-1.17), 0.91 (0.75-1.11), and 0.70 (0.57-0.86), respectively (P-trend < 0.01). BCAA intake and obesity were also inversely associated (P-trend = 0.03). In conclusion, higher dietary BCAA intake is associated with lower prevalence of overweight status/obesity among apparently healthy middle-aged adults from East Asian and Western countries.

Fish Consumption and Incidence of Diabetes: Meta-analysis of data from 438,000 individuals in 12 independent prospective cohorts with an average 11-year follow-up

OBJECTIVE —Ecological data suggest an inverse correlation between fish consumption and diabetes prevalence. However, epidemiological data on fish intake and diabetes incidence are controversial and inconclusive. Therefore, we aimed to assess the literature and determine the association between fish consumption and diabetes risk quantitatively. RESEARCH DESIGN AND METHODS —Prospective cohort studies published through August 2011 in peer-reviewed journals indexed in PubMed were selected. Additional information was retrieved through Google or a hand search of the references from relevant articles. The weighted relative risk (RR) and corresponding 95% CI for incident diabetes was estimated using random-effects models. RESULTS —A database was derived from nine eligible studies (12 independent cohorts), including 438,214 individuals with an average 11.4-year follow-up. Compared with those who never consumed fish or ate fish less than once per month, the pooled RR of incident diabetes was 0.99 (95% CI 0.85–1.16) for individuals who ate fish five or more times per week (Ptrend = 0.80). Similar results were found for long-chain n-3 polyunsaturated fatty acid intake. Study location was an effect modifier. An inverse association between fish intake and diabetes incidence was found by combining studies conducted in Eastern but not Western countries. CONCLUSIONS —Accumulated evidence generated from this meta-analysis does not support an overall inverse association of fish or fish oil intake with incidence of diabetes. The null association was modified by study location (Eastern vs. Western countries), which may reflect the possible difference between Eastern and Western dietary patterns. Further studies are warranted.

Consumption of monosodium glutamate in relation to incidence of overweight in Chinese adults: China Health and Nutrition Survey (CHNS)

BACKGROUND It has been hypothesized that monosodium glutamate (MSG), a flavor enhancer, is positively associated with weight gain, which influences energy balance through the disruption of the hypothalamic signaling cascade of leptin action. OBJECTIVE The objective was to examine the longitudinal association between MSG consumption and incidence of overweight. DESIGN Data were collected from the China Health and Nutrition Survey (CHNS), a prospective open-cohort, ongoing nationwide health and nutrition survey, consisting of 10,095 apparently healthy Chinese adults aged 18-65 y at entry from 1991 to 2006. Diet, including MSG and other condiments, was assessed with a weighed food inventory in combination with three 24-h recalls. Incident overweight was defined as a body mass index (BMI; in kg/m(2)) ≥ 25 or ≥23 based on World Health Organization recommendations for Asian populations. Multilevel mixed-effects models were constructed to estimate change in BMI, and Cox regression models with gamma shared frailty were used to determine the incidence of overweight. RESULTS The mean follow-up was 5.5 y. The cumulative mean (±SD) MSG intake of 2.2 ± 1.6 g/d was positively associated with BMI after adjustment for potential confounders and cluster effects at different levels (individual, household, and community). The adjusted hazard ratio of overweight was 1.33 (95% CI: 1.01, 1.75; P for trend < 0.01) for participants in the highest quintile of MSG intake compared with those in the lowest quintile after adjustment for age, physical activity, total energy intake, and other major lifestyle factors. CONCLUSIONS MSG consumption was positively, longitudinally associated with overweight development among apparently healthy Chinese adults. Additional studies are needed to elucidate mechanisms of action and to establish causal inference.

Fish consumption and risk of stroke and its subtypes: accumulative evidence from a meta-analysis of prospective cohort studies.

BACKGROUND/OBJECTIVES:To provide a reliable assessment of the hypothesized association of fish consumption with stroke risk accumulatively, an updated meta-analysis of published prospective cohort studies was conducted.SUBJECTS/METHODS:Prospective cohort studies through April 2012 in peer-reviewed journals indexed in MEDLINE and EMBASE were selected. Additional information was retrieved through Google or a search of the reference list in relevant articles. The main outcome measure was the weighted hazards ratio (HR) and corresponding 95% confidence interval (CI) for incident stroke according to fish consumption using a random-effects model.RESULTS:A database was derived from 16 eligible studies (19 cohorts), including 402 127 individuals (10 568 incident cases) with an average 12.8 years of follow-up. Compared with those who never consumed fish or ate fish <1/month, the pooled adjusted HRs of total stroke risk were 0.97 (95% CI, 0.87–1.08), 0.86 (0.80–0.93), 0.91 (0.85–0.98) and 0.87 (0.79–0.96) for those who consumed fish 1–3/month, 1/week, 2–4/week and ⩾5/week, respectively (Plinear trend=0.09; Pnonlinear trend=0.02). Study location was a modifier. An inverse association between fish intake and stroke incidence was only found by studies conducted in North America. The modest inverse associations were more pronounced with ischemic stroke and were attenuated with hemorrhagic stroke.CONCLUSIONS:Accumulated evidence generated from this meta-analysis suggests that fish intake may have a protective effect against the risk of stroke, particularly ischemic stroke.

Dietary magnesium intake is inversely associated with serum C-reactive protein levels: meta-analysis and systematic review

Objectives To quantitatively summarize the association of dietary magnesium (Mg) intake with serum C-reactive protein (CRP) levels in the general population. Methods Observational and experimental studies through February 2013 were reviewed in PubMed and EMBASE. Additional information was retrieved through Google or hand search of related reference lists. The main outcome is either adjusted geometric mean of CRP or odds ratio (OR) of having serum CRP≥3 mg/L. Meta-regression was used to determine the linear association of dietary Mg intake and adjusted geometric means of CRP levels. A fixed-effects model was used to pool ORs of interest, comparing those in the lowest with those in the highest group of dietary Mg intake. Results A dataset derived from seven cross-sectional studies including 32,918 participants was quantitatively assessed. A weighted inverse association between Mg intake and serum CRP levels was observed[β coefficient: −0.0028; 95% CI, −0.0043 to −0.0013; P for trend=0.001] from four cross-sectional studies. The pooled OR (95%CI) of having CRP≥3 mg/L was 1.49(1.18 to 1.89) comparing the lowest to the highest group of Mg intake from three studies with data available. Qualitative assessment among five intervention studies also showed a potential beneficial effect of Mg intake on serum CRP levels. Conclusion This meta-analysis and systematic review indicate that dietary Mg intake is significantly and inversely associated with serum CRP levels. The potential beneficial effect of Mg intake on chronic diseases may be, at least in part, explained by inhibiting inflammation.

Mercury Exposure in Young Adulthood and Incidence of Diabetes Later in Life: The CARDIA Trace Element Study

OBJECTIVE Laboratory studies suggest that exposure to methylmercury at a level similar to those found in fish may induce pancreatic islet β-cell dysfunction. Few, if any, human studies have examined the association between mercury exposure and diabetes incidence. We examined whether toenail mercury levels are associated with incidence of diabetes in a large prospective cohort. RESEACH DESIGN AND METHODS A prospective cohort of 3,875 American young adults, aged 20–32 years, free of diabetes in 1987 (baseline), were enrolled and followed six times until 2005. Baseline toenail mercury levels were measured with instrumental neutron-activation analysis. Incident diabetes was identified by plasma glucose levels, oral glucose tolerance tests, hemoglobin A1C levels, and/or antidiabetes medications. RESULTS A total of 288 incident cases of diabetes occurred over 18 years of follow-up. In multivariate analyses adjusted for age, sex, ethnicity, study center, education, smoking status, alcohol consumption, physical activity, family history of diabetes, intakes of long-chain n-3 fatty acids and magnesium, and toenail selenium, toenail mercury levels were positively associated with the incidence of diabetes. The hazard ratio (95% CI) of incident diabetes compared the highest to the lowest quintiles of mercury exposure was 1.65 (1.07–2.56; P for trend = 0.02). Higher mercury exposure at baseline was also significantly associated with decreased homeostasis model assessment of β-cell function index (P for trend < 0.01). CONCLUSIONS Our results are consistent with findings from laboratory studies and provide longitudinal human data suggesting that people with high mercury exposure in young adulthood may have elevated risk of diabetes later in life.

Fish oil, selenium and mercury in relation to incidence of hypertension: a 20‐year follow‐up study

Abstract.  Xun P, Hou N, Daviglus M, Liu K, Morris JS, Shikany JM, Sidney S, Jacobs DR, He K (Department of Nutrition, Gillings School of Global Public Health and School of Medicine and Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC; Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL; Research Reactor Center, University of Missouri‐Columbia, Columbia, MO; Division of Preventive Medicine, School of medicine, University of Alabama at Birmingham, Birmingham, AL; Division of Research, Kaiser Permanente Medical Care Program, Oakland, CA; Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN; and Department of Nutrition, University of Oslo, Oslo, Norway). Fish oil, selenium and mercury in relation to incidence of hypertension: a 20‐year follow‐up study. J Intern Med 2011; 270: 175–186.