Youth and Peer Mentor Led Interventions to Improve Biometric-, Nutrition, Physical Activity, and Psychosocial-Related Outcomes in Children and Adolescents: A Systematic Review.

The utilization of youth (older) and peer (same age) mentor-led interventions to improve nutrition and physical activity has been an emerging trend in recent years. This systematic review is intended to synthesize the effectiveness of these intervention programs on participants and mentors based on biometric, nutrition, physical activity, and psychosocial outcomes of youth and peer mentor-led interventions among children and adolescents. Online databases, including PubMed, ScienceDirect, EBSCOhost and Google Scholar, were searched, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. A three-step screening process was used to meet the proposed eligibility criteria, and the risk-of-bias tool for randomized trials (RoB 2) was used to assess bias for the included studies. Nineteen unique intervention programs and twenty-five total studies were deemed eligible when considering the criteria required for review. Multiple studies demonstrated positive evidence of the biometric and physical activity outcomes that were considered significant. The findings regarding the nutritional outcomes across the included studies were mixed, as some studies reported significant changes in eating habits while others did not find a significant change. Overall, the utilization of youth and peer mentor-led models in nutrition- and physical-activity-related interventions may be successful in overweight and obesity prevention efforts for those children and adolescents receiving the intervention and the youths and peers leading the interventions. More research is needed to explore the impact on the youths and peers leading the interventions and disseminating more detailed implementation strategies, e.g., training mentors would allow for advancements in the field and the replicability of approaches. Terminology: In the current youth- and peer-led nutrition and physical activity intervention literature, a varying age differential exists between the targeted sample and the peers, and varying terminology with regards to how to name or refer to the youth. In some instances, the youth mentors were individuals of the same grade as the target sample who either volunteered to serve in the peer role or were selected by their fellow students or school staff. In other cases, the youth mentors were slightly older individuals, either in high school or college, who were selected based upon their experience, leadership skills, passion for the project, or demonstration of healthy lifestyle behaviors.

Dietary calcium intake protects women consuming oral contraceptives from spine and hip bone loss.

CONTEXT: It is estimated that 80% of all women have used oral contraceptives (OCP), but OCP use may prevent attainment of maximal peak bone mass in young women and thus increase the risk of osteoporosis later in life. OBJECTIVE: This study examined whether increased calcium intake could reduce the detrimental effects of OCP use on bone mass in young women. DESIGN: The study design was a 1-yr intervention. SETTING: The study was performed in a general community setting. SUBJECTS: One hundred fifty-four young (18-30 yr old) healthy women with a dietary calcium intake of less than 800 mg/d began the study, and 135 completed the trial. INTERVENTION: Subjects were randomly assigned to one of three diet intervention groups: 1) control, continuous established (<800 mg/d) dietary calcium intake; 2) medium dairy, increase calcium intake to approximately 1000-1100 mg/d; and 3) high dairy, increase calcium intake to approximately 1200-1300 mg/d. Randomization was stratified by OCP use. MAIN OUTCOME MEASURES: The main outcome measures were total body bone mineral density (BMD) and content (BMC); total hip BMD, BMC, and bone area; and spine BMD, BMC, and bone area. RESULTS: Dairy product intervention positively impacted the percentage change in total hip BMD and BMC. In addition, dairy product intake prevented a negative percentage change in total hip and spine BMD in OCP users. CONCLUSION: Dairy product intake, at levels necessary to achieve the recommended intakes of calcium, protected the total hip BMD and spine BMD from loss observed in young healthy women with low calcium intakes who were using OCP.

Dairy products do not lead to alterations in body weight or fat mass in young women in a 1-y intervention.

BACKGROUND: Previous results suggested that increased intake of dairy calcium is associated with reduced weight and fat mass. OBJECTIVE: The purpose of this study was to determine whether long-term increases in consumption of dairy calcium alter body weight and fat mass in young, healthy women. DESIGN: We used a randomized, 1-y intervention for dairy calcium. Subjects were 155 young (aged 18-30 y), healthy, normal-weight women with intake of dietary calcium < 800 mg/d and energy intake

Fat oxidation and its relation to serum parathyroid hormone in young women enrolled in a 1-y dairy calcium intervention.

BACKGROUND: Increased dietary calcium is associated with changes in body composition. One proposed mechanism is that dietary calcium increases fat oxidation, potentially via regulation of serum parathyroid hormone (PTH) concentrations. OBJECTIVES: The objectives of the study were to determine whether acute or chronic increased dairy calcium intakes alter postprandial whole-body fat oxidation and whether the increased intake is related to changes in PTH concentrations. DESIGN: Normal-weight women aged 18-30 y were randomly assigned to a low (<800 mg/d, control; n = 10) or high (1000-1400 mg/d; n = 9) dietary calcium intake group for 1 y. Whole-body fat oxidation was assessed by measuring respiratory gas exchange after each subject consumed 2 isocaloric liquid meals containing 100 or 500 mg Ca at baseline and 1 y. Fasting serum PTH was measured at baseline and 1 y. RESULTS: The mean 1-y change in fat oxidation was higher in the high-calcium group than in the low-calcium control group after a low-calcium meal (0.10 +/- 0.05 compared with 0.005 +/- 0.04 g/min; P < 0.001) and a high-calcium meal (0.06 +/- 0.05 compared with 0.03 +/- 0.04 g/min; P < 0.05). The 1-y change in serum log PTH was negatively associated with the 1-y change in postprandial fat oxidation after a high-calcium meal (partial r = -0.46, P < 0.04) when controlled for the1-y change in total body fat mass. CONCLUSIONS: The results suggest that a chronic diet high in dairy calcium increases whole-body fat oxidation from a meal, and increases in fasting serum PTH relate to decreases in postprandial whole-body fat oxidation.

Can the controversial relationship between dietary calcium and body weight be mechanistically explained by alterations in appetite and food intake?

The prevalence of obesity has reached epidemic proportions worldwide and the incidence of overweight and obesity continues to rise. Diet plays a significant role in the modulation of body weight and there is some evidence to suggest that calcium or dairy intake may modulate body weight and body fat mass. Several mechanisms through which calcium or dairy products may affect body weight or fat have been suggested, including a possible effect on appetite and food intake. A recent study investigated to what extent people could compensate for increased energy intake from dairy products and found that a 7-day increase in dairy intake had no effect on appetite and no evidence of complete compensation for the raised energy intake. In another study, the effects of altered calcium content of a dairy-based test meal was evaluated in obese subjects; the findings indicated that although a higher calcium content of the meal reduced the extent of post-prandial chylomicron-associated triglyceridemia, there was no effect on appetite-related hormones (CCK, ghrelin, GLP-1, or PPY) or on energy intake from a subsequent ad libitum test meal. Thus, this new evidence does not support the hypothesis that high calcium or dairy intake reduces appetite or food intake.

Effect of 1-year dairy product intervention on fat mass in young women: 6-month follow-up.

OBJECTIVE: Previous results from this laboratory suggest that a 1-year dairy intake intervention in young women does not alter fat mass. The objective of this study was to determine the impact of the 1-year dairy intervention 6 months after completion of the intervention. RESEARCH METHODS AND PROCEDURES: Previously, normal-weight young women (n = 154) were randomized to one of three calcium intake groups: control (<800 mg/d), medium dairy (1000 to 1100 mg/d), or high dairy (1300 to 1400 mg/d) for a 1-year trial (n = 135 completed). In the current study, 51 women were assessed 6 months after completion of the intervention trial. Body compositions (body fat, lean mass) were measured using DXA. Self-report questionnaires were utilized to measure activity and dietary intake (kilocalories, calcium). RESULTS: The high-dairy group (n = 19) maintained an elevated calcium intake (1027 +/- 380 mg/d) at 18 months compared with the control group (n = 18, 818 +/- 292; p = 0.02). Mean calcium intake over the 18 months predicted a negative change in fat mass (p = 0.04) when baseline BMI was controlled in regression analysis (model R(2) = 0.11). 25-Hydroxyvitamin D levels were correlated with fat mass at each time-point (baseline, r = -0.41, p = 0.003; 12 months, r = -0.42, p = 0.002; 18 months, r = -0.32, p = 0.02) but did not predict changes in fat mass. DISCUSSION: Dietary calcium intake over 18 months predicted a negative change in body fat mass. Thus, increased dietary calcium intakes through dairy products may prevent fat mass accumulation in young, healthy, normal-weight women.