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Objective To investigate the association between serum 25-hydroxyvitamin D concentrations (25(OH)D) and mortality in a large consortium of cohort studies paying particular attention to potential age, sex, season, and country differences.Design Meta-analysis of individual participant data of eight prospective cohort studies from Europe and the US. Setting General population.Participants 26 018 men and women aged 50-79 years

BackgroundInvalid information on dietary intake may lead to false diet-disease associations. This study was conducted to examine the relative validity of the food frequency questionnaire (FFQ) used to assess dietary intake in the Leiden Longevity Study.MethodsA total of 128 men and women participating in the Leiden Longevity Study were included in the present validation study. The performance of the FFQ was evaluated using the mean of three 24-hour recalls as the reference method. Evaluation in estimating dietary intake at the group level was done by paired t-tests. The relative validity of the individual energy adjusted level of intake was assessed with correlation analyses (Pearson’s), with correction for measurement error.ResultsOn group level, the FFQ overestimated as well as underestimated absolute intake of various nutrients and foods. The Bland and Altman plot for total energy intake showed that the agreement between the FFQ and the 24-hour recalls was dependent of intake level. Pearson correlation coefficients ranged from 0.21 (alpha linolenic acid) to 0.78 (ethanol) for nutrients and from -0.02 (legumes, non-significant) to 0.78 (alcoholic beverages) for foods. Adjustment for energy intake slightly lowered the correlation coefficients for nutrients (mean coefficient: 0.48 versus 0.50), while adjustment for within-subject variation in the 24-h recalls resulted in higher correlation coefficients for both nutrients and foods (mean coefficient: 0.69 for nutrients and 0.65 for foods).ConclusionsFor most nutrients and foods, the ability of the FFQ to rank subjects was acceptable to good.

Calcium plays a role in blood pressure (BP) regulation, but the importance of supplemental calcium intake for the prevention of hypertension is still debated. We conducted a meta-analysis of randomized controlled trials to determine the effect of calcium supplementation on BP. A systematic search for randomized trials of calcium supplementation and BP in non-pregnant subjects was performed in Medline from 1966 to June 2003. Seventy-one trials were identified, 40 of which met the criteria for meta-analysis (total of 2492 subjects). Two persons independently extracted data from original publications on changes in calcium intake and BP. In addition, data were collected on subjects' characteristics, that is, age, gender, initial BP and initial calcium intake. A random effects model was used to obtain the effect of calcium supplementation on BP, overall and in predefined population subgroups. Calcium supplementation (mean daily dose: 1200 mg) reduced systolic BP by À1.86 mm Hg (95% confidence interval: À2.91 to À0.81) and diastolic BP by À0.99 mm Hg (À1.61 to À0.37). In people with a relatively low calcium intake (p800 mg per day) somewhat larger BP estimates were obtained, that is, À2.63 (À4.03 to À1.24) for systolic BP and À1.30 (À2.13 to À0.47) for diastolic BP. Our study suggests that an adequate intake of calcium should be recommended for the prevention of hypertension. More research on BP in people with calcium-deficient diets is warranted.

Background:Little is known about the effects of dietary fiber intake on long-term mortality. Objective: We aimed to study recent and long-term dietary fiber intake in relation to coronary heart disease and all-cause mortality. Design: The effects of recent and long-term dietary fiber intakes on mortality were investigated in the Zutphen Study, a cohort of 1373 men born between 1900 and 1920 and examined repeatedly between 1960 and 2000. During that period, 1130 men died, 348 as a result of coronary heart disease. Hazard ratios were obtained from timedependent Cox regression models. Results: Every additional 10 g of recent dietary fiber intake per day reduced coronary heart disease mortality by 17% (95% CI: 2%, 30%) and all-cause mortality by 9% (0%, 18%). The strength of the association between long-term dietary fiber intake and all-cause mortality decreased from age 50 y (hazard ratio: 0.71; 95% CI: 0.55, 0.93) until age 80 y (0.99; 0.87, 1.12). We observed no clear associations for different types of dietary fiber. Conclusions: A higher recent dietary fiber intake was associated with a lower risk of both coronary heart disease and all-cause mortality. For long-term intake, the strength of the association between dietary fiber and all-cause mortality decreased with increasing age.