Suchergebnisse

"The National Health and Nutrition Examination Survey (NHANES) collects information on both dietary intake and health conditions from a complex sample of individuals in the US. Instrumental-variable regression can be used to model an individual's health-related attribute as a linear function of explanatory variables including the average daily intake of dietary components. This overcomes the apparent limitation of the NHANES collecting dietary intake data on only two days per sampled individual because the averages of two days per individual exhibit considerable intra-individual variability. Readily available software routines can perform survey-sensitive instrumental-variable regression with data like that collected by the NHANES, but the relevant quantitative literature is not clear about what parameters these routines are actually estimating. The authors fit the long-term (usual) serum beta-carotene level of a population of women aged 20-64 to a linear function of each woman's long-term average (usual) daily beta-carotene intake from food and other explanatory variables using survey-sensitive instrumental regression and provide two interpretations of the results." (author's abstract)

Recent Institute of Medicine (IOM) reviews of the process for deriving Dietary Reference Intakes (DRIs) suggest that determining the need for a new nutrient review should be evaluated against criteria set a priori. After selecting the criterion of significant new and relevant research, a working group of US and Canadian government scientists used results from a systematic review and 2 conferences on vitamin D and health to evaluate whether significant new and relevant scientific evidence had become available since the 1997 IOM publication of the DRIs for vitamin D. This working group concluded that there appears to be new research meeting the criteria for 4 key DRI questions. The new research is of larger quantity and quality for the elderly than for other groups, but overall 1) adds to the bone-related and status evidence available to the 1997 DRI Committee for several of the life-stage groups, 2) identifies new outcomes with respect to risk of falls and performance measures in the elderly and potential adverse effects, and 3) provides additional information on dose-response relations between intakes and circulating 25-hydroxyvitamin D concentrations and between 25-hydroxyvitamin D concentrations and several health outcomes (ie, bone-related outcomes for all ages and risk of falls and performance measures in older adults). Members of the working group concluded that significant new and relevant research was available for reviewing the existing DRIs for vitamin D while leaving the decision of whether the new research will result in changes to the current DRIs to a future IOM-convened DRI committee.