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Individual participant data-level meta-regression (IPD) analysis is superior to meta-regression based on aggregate data in determining Dietary Reference Values (DRV) for vitamin D. Using data from randomized controlled trials (RCTs) with vitamin DIPD analysis using data from 1429 participants (ages 2-89 years) in 11 RCTs with vitamin D-fortified foods identified via a systematic review and predefined eligibility criteria. Outcome measures were vitamin D DRV estimates across a range of serum 25(OH)D thresholds using unadjusted and adjusted models.Our IPD-derived estimates of vitamin D intakes required to maintain 97.5% of winter 25(OH)D concentrations ≥ 25 and ≥ 30 nmol/L are 6 and 12 µg/day, respectively (unadjusted model). The intake estimates to maintain 90%, 95% and 97.5% of concentrations ≥ 50 nmol/L are 33.4, 57.5 and 92.3 µg/day, respectively (unadjusted) and 17.0, 28.1 and 43.6 µg/day, respectively (adjusted for mean values for baseline serum 25(OH)D, age and BMI).IPD-derived vitamin D intakes required to maintain 90%, 95% and 97.5% of winter 25(OH)D concentrations ≥ 50 nmol/L are much higher than those derived from standard meta-regression based on aggregate data, due to the inability of the latter to capture between person-variability. Our IPD provides further evidence that using food-based approaches to achieve an intake of 12 µg/day could prevent vitamin D deficiency (i.e., serum 25(OH)D 30 nmol/L) in the general population.

Obesity prevalence is higher among rural populations than urban, including youth. Reduced physical activity levels are associated with childhood obesity. It could be assumed that the obesity disparity between rural and urban children is attributable, in part, to differences in physical activity levels; however, previous research quantifying and comparing physical activity levels between rural and urban youth are mixed. Lifestyle may be more important than geographic location in determining physical activity levels. Therefore, the objective of this study was to compare sex and lifestyle group (Hutterite vs. non-Hutterite) differences in physical activity in a free-living, rural pediatric population.Youth (n=58) were instructed to wear accelerometers for seven days. Mean percent time in light, moderate or vigorous activity during waking hours was calculated. Two-way ANOVAs and multiple regression models were used for analyses.Percent time in vigorous activity was significantly greater for Hutterite males than Hutterite females, and Hutterite males had greater percent time in vigorous activity and moderate plus vigorous activity than non-Hutterite males.There is evidence to support differences in rural lifestyles to be associated with differences in physical activity levels between children living in the same geographic location, particularly among males. Active transportation and having a safe environment for unstructured outdoor play may account for activity and lifestyle differences between the two rural groups.

Individuals with cystic fibrosis (CF) have low bone density and increased fracture risk.Cross-sectional study investigating whole body bone mineral content (WBBMC), bone geometry and strength in 12 children with CF compared to 23 age- and sex-matched controls with and without adjusting for age, height, and body composition.CF group had lower WBBMC than controls (P = 0.007) with larger differences at older ages (age-by-group, P = 0.08). CF group had decreased height (P = 0.006), a trend of lower lean mass per height (P = 0.08), and no difference in relationship between WBBMC and lean mass compared to controls (P = 0.65). Periosteal and endosteal circumferences were smaller in CF (each, P = 0.02). Positive relationships of cortical area and bone strength with age were attenuated with CF (group-by-age; each, P 0.01).Children with CF have similar WBBMC relative to lean mass as controls. Cortical bone area and bone strength were less in CF group compared to controls, with greater differences in older children.

The National Children's Study (NCS) is a longitudinal study of environmental influences on children's health. Recruitment of a representative birth cohort that will be followed until 21 years of age requires unique approaches across the nationwide study communities.To describe community outreach and engagement in preparation for household recruitment of women of childbearing age at a rural-classified NCS location that includes 4 adjacent Northern Plains counties spanning 2,500 square miles.Outreach and engagement methods focused on rural community characteristics. The team established an advisory council, conducted outreach meetings with agencies and groups, participated in local events, and collaborated with stakeholders. Study awareness was raised using radio announcements, local television stories, and widespread distribution of print materials through churches, businesses, and child care centers. Impact evaluation examined the number of stakeholder events by type. Outcome evaluation examined the number of households contacted for recruitment, numbers of age-eligible women who completed the screening, and exploration of whether women had heard about the study.Over 300 outreach events occurred, ranging from tribal council meetings to parade entries. Recruitment outcomes were as follows: (1) 80% of 14,700 non-vacant households were reached for potential recruitment; (2) screening interviews were conducted with 89% of the 5,800 age-eligible women identified; and (3) 53% of women who completed the screening had heard about the study.Outreach targeted to rural communities facilitated strong recruitment outcomes. Collaboration with the cooperative extension service was a unique rural asset that facilitated relevant activities. Participant retention is an ongoing priority.

Exercise is beneficial for bone when adequate nutrition is provided. The role of protein consumption in bone health, however, is controversial.The objective was to ascertain the effect of high protein intake on insulin-like growth factor I (IGF-I) and markers of bone turnover during 6 mo of exercise training.Fifty-one subjects aged 18-25 y (28 men, 23 women) received a protein supplement (42 g protein, 24 g carbohydrate, 2 g fat) or a carbohydrate supplement (70 g carbohydrate) twice daily. Exercise consisted of alternating resistance training and running 5 times/wk. Plasma concentrations of IGF-I, insulin-like growth factor-binding protein 3, serum bone alkaline phosphatase, and urinary N-telopeptide collagen crosslink (NTx) concentrations were measured at 0, 3, and 6 mo after 24 h without exercise and a 12-h fast.Three-day diet records indicated no difference in energy intake between the groups. Average protein intakes after supplementation began in the protein and carbohydrate groups were 2.2 +/- 0.1 and 1.1 +/- 0.1 g/kg, respectively (P0.001). The increase in plasma IGF-I was greater in the protein group than in the carbohydrate group (time x supplement interaction, P = 0.01). There were no significant changes over time or significant differences by supplement in plasma insulin-like growth factor-binding protein 3 (44 and 40 kDa). Serum bone alkaline phosphatase increased significantly over time (P = 0.04) and tended to be higher in the protein group than in the carbohydrate group (P = 0.06). NTx concentrations changed over time (time and time squared; P0.01 for both) and were greater in the protein group than in the carbohydrate group (P = 0.04). Men had higher NTx concentrations than did women (74.6 +/- 3.4 and 60.0 +/- 3.8 nmol/mmol creatinine; P = 0.005).Protein supplementation during a strength and conditioning program resulted in changes in IGF-I concentrations.