Efficacy of Optimal Levels of Dietary Dairy on Modulation of Adolescent Weight

描述（由申请人提供）：儿童和青少年肥胖在美国很流行，并且发病率呈上升趋势。这是值得关注的，因为儿童期肥胖一直延续到成年期，并与成人肥胖率和相关合并症相关。青春期是超重发展的关键时期，尤其是女孩。此外，平均而言，美国女孩的钙摄入量低于最佳水平。强有力的证据支持高钙饮食，特别是乳制品在预防超重和促进成年人减肥方面的功效。虽然观察性研究表明钙可以调节儿童的体重，但目前还没有发表的关于乳制品对儿童或青少年体重/体脂（BF）影响的随机对照试验的报告。拟议研究的目的是确定与继续低钙摄入的同类女性相比，习惯性低钙摄入的青春期女性将乳制品摄入量增加到推荐水平是否会减少BF增加。我们建议对身体质量指数（BMI）高于第50百分位且月经初潮后至少1年的13岁和14岁女孩进行1年的干预，以确定我们是否可以防止BF过度增加。假设是：月经初潮后的青春期女孩习惯性地低钙摄入，每天摄入至少1200毫克钙的乳制品，在一年内，其BF百分比的增长比月经初潮后每天摄入600毫克或更少钙的青春期女孩要小。我们将招募321名健康女孩，并进行为期两周的磨合，以评估她们对高乳制品饮食的耐受能力。我们将招募274名符合条件的女孩，并按BMI-百分位数（百分位数）随机分配到高乳制品饮食组或正常饮食组。排除标准包括：全身骨矿物质含量（TBBMC） Z评分<-2；怀孕、乳糖不耐症、月经初潮或任何健康问题。体重指数超过85百分位的女孩只有在其私人医生的批准下才有资格。每隔6个月，我们将评估体脂率、TBBMC、Tanner分期、身高、体重、腰围和腹部围。每季度对饮食摄入和身体活动进行评估。拟议的研究直接关系到新研究中心预防疾病的任务。这项研究的积极结果将导致一种安全、廉价的营养方法来预防青春期女孩的超重和相关的合并症。这可能会降低他们成人肥胖的风险，并将为进一步研究男性青少年和年幼的儿童提供支持。公共卫生相关性：该项目的目的是确定将青春期女孩的乳制品摄入量增加到目前推荐的水平（每天4份）是否会降低她们超重的风险。这项研究的积极结果将为今后发展一种安全、廉价、促进健康的预防青春期女孩超重的方法奠定基础，并为今后在青春期男孩和更年幼的儿童中进行研究提供依据。这种乳制品干预与目前推荐的钙和乳制品摄入量是一致的。

DESCRIPTION (provided by applicant): Childhood and adolescent obesity is epidemic in the US, and the incidence is increasing. This is of concern because childhood obesity tracks into adulthood and is associated with higher rates of adult obesity and related co-morbidity. Adolescence is a critical period for the development of overweight, especially for girls. Also, on average, girls in the US have sub-optimal calcium intakes. Strong evidence supports the efficacy of a diet high in calcium, particularly in dairy food, in preventing overweight and facilitating weight loss in adults. Although observational studies suggest that calcium modulates weight in children, there are no published reports of randomized, controlled trials of the effect of dairy foods on weight/body fat (BF) in children or adolescents. The goal of the proposed research is to determine if increasing intake of dairy foods to recommended levels in adolescent females with habitually low calcium intake will decrease BF gain compared to similar females who continue their low calcium intake. We propose a 1-year intervention in 13- and 14-year old girls who are above the 50th percentile for body mass index (BMI) and are at least 1= years post- menarche to determine if we can prevent excessive BF gain. The hypothesis is: Post-menarcheal adolescent girls with habitually low calcium intake who consume dairy foods providing at least 1200 mg of calcium/day will have a smaller increase in percent BF during 1 year than post-menarcheal adolescent girls on a usual diet of 600 mg of calcium/day or less. We will recruit 321 healthy girls and conduct a 2-week run-in to assess their ability to tolerate a high dairy diet. We will enroll 274 eligible girls and randomly assign them, stratified by BMI- percentile (percentile), to a high dairy diet or their usual diet. Exclusion criteria include: total body bone mineral content (TBBMC) Z score <-2; pregnancy, lactose intolerance, early menarche, or any health problem. Girls > 85th percentile of BMI will be eligible only with approval of their personal physician. At 6-month intervals we will assess percent body fat, TBBMC, Tanner stage, height, weight, waist circumference, and abdominal girth. Dietary intake and physical activity will be assessed quarterly. The proposed study directly relates to the NINR Mission to prevent disease. Positive findings from this study will result in a safe, inexpensive nutritional method of preventing overweight and the related co-morbidity in adolescent girls. This may decrease their risk of adult obesity and will provide support for further studies in male adolescents and in younger children. PUBLIC HEALTH RELEVANCE: The purpose of this project is to determine if increasing intake of dairy foods to currently recommended levels (4 servings per day) in adolescent girls will decrease the risk of their becoming overweight. Positive findings from this study will form the basis for the future development of a safe, inexpensive, health-promoting method of preventing overweight in adolescent girls and provides the rationale for future studies in adolescent boys and in younger children. Such a dairy intervention would be congruent with currently recommended calcium and dairy intake.