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

描述(申请人提供)：儿童和青少年肥胖症在美国很流行，而且发病率还在增加。这是令人担忧的，因为儿童肥胖症一直持续到成年，与较高的成人肥胖率和相关的共同发病率有关。青春期是超重发展的关键时期，对女孩来说尤其如此。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在预防成年人超重和促进减肥方面的有效性，特别是在乳制品中。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道。这项拟议研究的目的是确定与继续低钙摄入量的类似女性相比，习惯性低钙摄入量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13岁和14岁的女孩进行为期一年的干预，这些女孩的体重指数(BMI)超过50%，并且至少在月经初潮后1年，以确定我们是否可以防止BF过度增加。假设是：习惯于低钙摄入量的月经后青春期女孩，每天食用至少1200毫克钙的乳制品，在一年内BF百分比的增幅将小于月经后青春期女孩，通常饮食中钙含量为600毫克/天或更少。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，并随机将她们按BMI-百分位数(百分位数)分层，分配给高乳制品饮食或她们通常的饮食。排除标准包括：全身骨矿含量(TBBMC)Z评分&lt；-2；怀孕、乳糖不耐受、月经初潮早期或任何健康问题。体重指数第85百分位数的女孩只有在其私人医生批准的情况下才有资格。每隔6个月，我们将评估体脂百分比、TBBMC、Tanner分期、身高、体重、腰围和腹围。饮食摄入量和体力活动将按季度进行评估。这项拟议的研究与NINR预防疾病任务直接相关。这项研究的积极发现将导致一种安全、廉价的营养方法，以防止青春期女孩超重和相关的共同发病率。这可能会降低他们成年后肥胖的风险，并将为进一步研究男性青少年和年幼儿童提供支持。与公共卫生相关：该项目的目的是确定青春期女孩增加乳制品摄入量到目前推荐的水平(每天4份)是否会降低她们超重的风险。这项研究的积极发现将为未来开发一种安全、廉价、促进健康的预防青春期女孩超重的方法奠定基础，并为未来对青春期男孩和年幼儿童的研究提供理论基础。这样的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.