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流行，发病率正在增加。这是令人关注的，因为儿童肥胖症会影响到成年，并与成人肥胖症和相关并发症的发病率较高有关。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调节儿童的体重，但尚未发表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报告。拟议研究的目标是确定与继续低钙摄入的类似女性相比，习惯性低钙摄入的青少年女性增加乳制品摄入量至推荐水平是否会降低BF增益。我们建议对13和14岁的女孩进行1年的干预，这些女孩的体重指数（BMI）高于第50百分位数，并且月经初潮后至少1年，以确定我们是否可以防止BF过度增加。假设是：习惯性低钙摄入的月经初潮后少女，如果每天摄入至少1200毫克钙的乳制品，那么在1年内，其BF百分比的增加幅度小于月经初潮后少女日常饮食中钙摄入量为600毫克或更少的情况。我们将招募321名健康少女，进行为期2周的导入期，以评估她们耐受高乳制品饮食的能力。我们将招募274名符合条件的女孩，并将她们随机分配，按BMI百分位数（百分位数）分层，高乳制品饮食或其日常饮食。排除标准包括：全身骨矿物质含量（TBBMC）Z评分<-2;怀孕、乳糖不耐受、初潮早或任何健康问题。BMI> 85百分位数的女孩只有在其私人医生的批准下才有资格。每隔6个月，我们将评估体脂百分比、TBBMC、坦纳分期、身高、体重、腰围和腹围。饮食摄入量和体力活动将每季度进行评估。拟议的研究与国家核研究所预防疾病的使命直接相关。这项研究的积极结果将导致一个安全，廉价的营养方法，防止超重和相关的并发症的青春期女孩。这可能会降低他们成年肥胖的风险，并将为进一步研究男性青少年和幼儿提供支持。 公共卫生相关性：该项目的目的是确定将乳制品摄入量增加到目前推荐的水平（每天4份）是否会降低青春期女孩超重的风险。这项研究的积极结果将为今后开发一种安全、廉价、促进健康的预防少女超重的方法奠定基础，并为今后在青春期男孩和幼儿中进行的研究提供依据。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.