青春前期女童钙代谢实验研究

目的:研究我国青春前期女童钙代谢状况,初步探讨该时期女童钙需要量。方法:选择49名处于生长突增期、未月经初潮的青春前期女童,采用经典钙代谢实验方法,在600～1500mg/d范围内设计4个不同的钙摄入剂量组,观察研究对象的钙代谢状况。结果:在600～1500mg/d钙摄入量范围内,各组对象钙表观钙吸收率未发现差别,平均吸收率为(53±0.12)%(范围52%～55%)。采用非线性回归模型对钙摄入量和钙储留量的关系进行拟合,钙摄入量在500mg/d时,钙储留量处于较低水平,钙摄入量在500～1000mg/d时,储留量快速增加,当钙摄入量达到1100mg/d时,钙储留量稳定在500mg/d左右的平台水平。结论:我国青春前期女童钙的表观吸收率为(53±0.12)%;青春前期女童达到最大钙储留量的最低钙摄入量是1100mg/d。     

膳食蛋白质水平及含硫氨基酸对人体钙代谢的影响

目的：了解在我国实际膳食情况下，增加蛋白质摄入量对钙代谢的影响。方法：７名２４～３１岁的健康男性青年于４个实验期中分别轮流摄取四种不同的膳食，包括：基础膳食；基础膳食加４０ｇ鸡蛋白蛋白质；基础膳食加蛋氨酸１．９ｇ和胱氨酸１．７ｇ；以及基础膳食加牛磺酸２．４ｇ。然后观察尿钙、钙吸收及钙平衡的变化。结果：各膳食期钙的表观吸收率均无差异，补充蛋白质或补充蛋氨酸和胱氨酸使尿硫酸根及尿钙排泄量显著高于基础膳食期，并且钙平衡也均降低。补充牛磺酸对尿钙和钙平衡均无影响。结论：高蛋白质摄入对钙平衡的负面影响与含硫氨基酸蛋氨酸和胱氨酸的分解产物硫酸根排出增加有关     

膳食钙摄入量与青春前期女童骨量关系的研究

目的:研究青春前期女童膳食钙摄入量与骨量的关系,为指导合理钙营养提供科学依据。方法:采用双能X线骨密度测量仪测量年龄在10±1岁的194名青春前期女童全身及多位点骨密度和骨矿物质含量,采用食物频数及3d膳食询问法调查膳食钙摄入量,问卷法调查体力活动。结果:日均钙摄入量与所测各位点骨矿物质含量及骨密度均呈显著正相关;日均钙摄入量平均从257mg增加到759mg,不同位点的骨矿物质含量和骨密度分别增加13%～22%和3.6%～16%。结论:增加青春前期女童膳食钙摄入量有助于获得较高骨量和骨密度。     

膳良蛋白质水平及含硫氨基酸对人体钙代谢的影响

目的：了解在我国实际膳食情况下，增加蛋白质摄入量对钙代谢的影响。方法：７名２４￣３１岁的健康男性青年于４个实验期中分别轮流摄取四种不同的膳食，包括：基础膳食；基础膳食加４０ｇ鸡蛋白蛋白质；基础膳食加蛋氨酸１．９ｇ和胱氨酸１．７ｇ；以及基础膳食加牛磺酸２．４ｇ。然后观察尿钙，钙吸收及钙平衡的变化。结果：各膳食期钙的表观吸收率均无差异，补充蛋白质或补充蛋氨酸和胱氨酸使尿硫酸根及尿钙排泄量显著高于基础膳     

钙摄入量对青春前期女童骨量增长的影响—两年随机干预实验

目的研究不同钙摄入量对于青春前期女童骨量增长的影响,为该人群钙适宜摄入量的修订提供科学依据。方法以年龄10.0±0.7岁的241名青春前期健康女童为对象,设计普通膳食组、牛奶补充组和钙剂补充组三组,总钙摄入量分别为600、900和1200mg/d,进行2年干预,采用多次称量及3d膳食询问法获得2年间日均膳食钙摄入量,使用双能X线骨密度仪测量干预前后全身、腰椎及近端股骨骨矿物密度和骨矿物含量。结果2年间三组的平均钙摄入量分别为552±61、864±139和1166±207mg/d;日均钙摄入量与全身、多位点骨矿物含量和骨矿物密度显著正相关;当日均钙摄入量达到864mg/d时,全身骨矿物含量增加值显著高于钙摄入量为552mg/d膳食组;当日均钙摄入量达到1166mg/d时,股骨颈骨矿物含量及骨矿物密度和腰椎骨矿物密度的增加值显著高于未达到1166mg/d的干预组。结论9～11.5岁的青春前期女童钙摄入量达到1166mg/d,全身特别是负重部位能获得较高骨矿物含量和骨矿物密度增长,提示青春前期钙适宜摄入量可能为1200mg/d。     

补钙对12～17岁青少年锌、铁吸收率的影响

目的通过代谢平衡实验探讨补钙对中国青春期少年锌、铁吸收率的影响。方法从320名参加1年补钙实验的4组12~17岁少年中,每组随机抽取男、女生各10人,共80人。采用代谢平衡的方法,收集研究对象10天内摄入的食品、排出的粪便和尿液样品,用电感耦合等离子体发射光谱法测定样品中的钙、铁、锌含量。结果不同补钙组之间钙摄入量有差异,但铁、锌摄入量差异无显著性。不同补钙组之间钙、铁、锌的表观吸收率差异无显著性。男生钙、铁、锌的表观吸收率平均为69.4%、12.5%和29.9%,女生的分别为46.4%、20.9%和35.3%。铁的表观吸收率与青春发育水平有关。男生钙摄入量为600~800mg/d时,钙、铁、锌的表观吸收率均处于相对较高水平(75.3%、23.2%和36.4%)。结论钙摄入量低于1400mg/d时,不影响12~17岁少年锌、铁的吸收率。当男生钙摄入量为600~800mg/d时,更有助于钙、铁、锌的吸收。     

12～17岁少年钙代谢实验研究

目的通过钙代谢平衡实验探讨中国青春期少年的钙参考摄入量。方法从320名参与1年补钙实验4组12～17岁的少年中,每组随机抽取男、女生各10人,共80人。采用钙代谢平衡实验的方法。实验期共10d,膳食适应3d后,开始7d的代谢试验。收集研究对象试验期内摄入的食品、排出的粪便和尿液样品,用电感耦合等离子体发射光谱法测定样品中的钙含量。结果不同水平钙摄入组间的钙吸收量、粪钙排出量、钙储留量存在差异。钙表观吸收率女生平均为46.4%,男生68.7%。进行曲线拟合后,男生钙吸收率最高时的钙摄入量为665mg/d,女生钙吸收率达到平台时的钙摄入量为650mg。为了达到每日最大储留量,男生钙摄入量要达到545mg/d,女生要达到1055mg/d。结论中国12～17岁男生和女生的钙适宜摄入量有很大差别,男生钙适宜摄入量约为600～700mg/d,女生为1000～1100mg/d。     

孕期不同钙摄入量对孕产妇钙代谢的影响

目的　研究孕期不同钙摄入量对孕产妇钙代谢的影响。方法　 36名孕妇通过膳食指导和监测按钙摄入量水平随机分为传统膳食组、膳食钙干预组和膳食加钙剂联合干预组 ,对孕产期有关钙代谢指标、骨钙素及产后 45天骨密度监测。结果　血清钙磷各期各组间无差异 ( P>0 .0 5) ,随孕期进展钙吸收率、钙贮留量、血清碱性磷酸酶和尿羟脯氨酸增加 ,孕末期达高峰 ,产后下降 ;骨钙素也增加 ,产后仍增加 ;粪钙和尿钙降低 ,产后粪钙略增加而尿钙明显降低。母体腰椎骨密度组间差异显蓍 ( P<0 .0 1 )。钙摄入量与尿钙、钙贮留量和骨钙素呈正相关 ( r>0 .53,P<0 .0 1 ) ,与钙吸收率呈负相关 ( r=- 0 .51 ,P<0 .0 1 )。结论　我国传统膳食导致孕期低钙摄入情况下 ,母体虽可通过降低尿钙和粪钙的排泄 ,增加肠道钙吸收率和骨钙动员等调节 ,维持胎儿钙需要和自身血钙稳定 ,产生对摄入低钙的适应 ,但这种适应是有限的 ,不能达到较高钙贮留来满足妊娠期钙需要 ,对自身骨健康和代谢有一定影响 ,因此孕期应强调富钙食物、钙剂和 VD的补充     

彝族成年男子膳食中铁、锌、钙的生物利用研究

目的:评价彝族成年男子膳食中铁、锌和钙的生物利用情况,为防治该人群矿物质缺乏病提供基础信息。方法:以代谢平衡法于现场对12名20~22岁彝族世居地的成年男子进行14d试验。试验开始,收集对象空腹血,检测血红蛋白、红细胞压积、血清铁蛋白、血浆锌和钙浓度。试验期间,收集4~12d试验膳及摄入试验膳后排出的粪便和尿样。应用火焰原子吸收法测定膳食、粪便和尿中三种矿物质的含量,分别计算出它们的表观吸收率、平衡状态和表观利用率。结果:彝族成年男子代表性膳食中铁、锌和钙的表观吸收率(%)分别为15.8±6.2、24.5±4.1、32.3±9.7;表观利用率(%)分别为1.9±5.7、12.8±4.3、5.5±15.9。平衡试验显示铁,锌,钙均为平衡,但钙的变动范围较大。结论:膳食中铁、锌摄入量能满足试验对象的需要量,而钙的摄入量则不能满足其需要量。三种矿物质的表观吸收率与表观利用率基本上与我国正常人相同。建议彝族居民增加钙含量高的食物摄入量,以预防钙缺乏。     

青春前期儿童膳食中铁的吸收状况研究

目的探讨青春前期儿童膳食铁的吸收率及相关影响因素。方法选择60名北京地区青春前期儿童,男女各半,依当地饮食习惯制定食谱,进行为期11d的代谢平衡试验,收集试验期内全部粪便样品,以双份饭法收集膳食及水样。样品经冷冻干燥、粉碎、微波消解后,以原子吸收法(AAS)测定铁量,同时对膳食样品中可能影响铁吸收的因子含量进行测定,并以代谢平衡法(MB法)测定铁吸收率。结果男、女性儿童铁的吸收率(%)为8.05±0.90和9.13±0.57,女性显著高于男性,(t=2.38,P<0.05),日均铁摄入量(mg)分别为13.6±2.4和12.8±1.7,分别占推荐营养素摄入量(RNI)的85.0%和71.1%;蛋白质日摄入量(g)分别为75.5±4.1和69.3±6.2,分别占RNI的107.8%和106.6%;维生素C(VC)摄入量(mg)分别为43.2±3.6和38.9±2.1,占RNI的48.0%和43.2%,低于推荐量;膳食纤维和植酸摄入量(g)分别为16.3±3.5、15.1±2.0和1.2±0.2、1.0±0.3。结论北京地区青春前期儿童铁的吸收率仍处于较低水平,女性高于男性。建议在增加膳食中血红素铁和VC摄入的同时,适当降低植酸和纤维素的摄入,以提高铁的吸收率。     

Calcium retention in adolescent boys on a range of controlled calcium intakes

BACKGROUND: National calcium requirements in the United States for boys are based on data from girls. On average, boys develop larger skeletons than do girls, yet it is unknown whether the additional skeletal accretion in boys requires additional dietary calcium intake. OBJECTIVE: The objective was to determine calcium retention in adolescent boys in response to a range of controlled intakes and to compare the intake needed for maximal retention in boys with that needed in adolescent girls studied under the same conditions. DESIGN: Thirty-one boys aged 12-15 y participated in 3-wk metabolic balance studies testing a range (700-2100 mg/d) of calcium intakes in a crossover study design with a 2-wk washout period. Calcium intake was varied by using a beverage fortified with calcium citrate malate. After a 1-wk equilibration period, calcium retention was calculated as dietary calcium intake minus the calcium excreted in the feces and urine over the following 2 wk. The dietary intake at which maximal calcium retention occurred was determined by using a nonlinear regression model. The results in boys were compared with those obtained in 35 adolescent girls previously studied under the same protocol. RESULTS: Maximal calcium retention in boys was achieved at an intake of 1140 mg/d. Calcium retention was higher (by 171 +/- 38 mg/d) in boys than in girls at all calcium intakes studied. CONCLUSION: The higher calcium retention in boys than in girls was attained through higher net calcium absorption and lower urinary excretion than in girls.     

青春早期女童体力活动与骨量关系的研究

目的探讨体力活动与青春前期女童骨量的关系。方法采用双能X线骨密度测量仪测量年龄在（10±1）岁的194名青春早期女童全身、股骨颈、Ward三角区和L1-L4的骨密度（BMD）和骨矿物质含量（BMC）,采用问卷和跟踪记录调查女童的体力活动和膳食钙摄入。结果日均承重和日均总体力活动能耗与上述位点BMD和BMC均显著正相关,而非承重体力活动与BMD和BMC无显著相关。BMD和BMC随着承重体力活动能耗增高而增高,平均能耗从950kJ（227kcal／d）增加到1737kJ（415kcal／d）时,各位点BMC增加17．5％～29．0％,BMD增加8．8％-17．1％。结论青春前期女童适当增加体力活动量,尤其是承重体力活动量,有助于获得更多的骨量积累。     

Lactating women restricting milk are low on select nutrients

OBJECTIVE: Currently there are no recommendations for vitamin/mineral supplementation for lactating women but supplementation may be important, particularly for those women who choose to restrict milk intake during lactation. The objective of this study was to assess nutrient adequacy for lactating women and compare their dietary intake, including supplements, between those who restrict milk and those who do not. METHODS: A cohort of 175 healthy exclusively breast-feeding women (19-45 yrs) recruited from prenatal classes were divided into milk restrictors (RS) defined as milk intake < or = 250 ml/day and non-restrictors (NRS) (>250 ml/day) and followed for six months postpartum. Participants provided repeated 24-hr dietary recalls, detailed use of vitamin/mineral supplements and reasons for restricting milk. Statistical Analyses: Observed intakes were adjusted to remove day-to-day variability. Nutrient intakes were estimated for macronutrients and vitamins C, D, thiamin, riboflavin, niacin, and minerals, calcium and zinc, with and without vitamin/mineral supplements. Chi-square was used to compare the number of RS and NRS with intakes less than the Estimated Average Requirement (EAR). RESULTS: Milk restriction was practiced by 23% of the sample. Sixty per cent of RS reported protein intakes 相似文献   

Meeting adequate intake for dietary calcium without dairy foods in adolescents aged 9 to 18 years (National Health and Nutrition Examination Survey 2001-2002)

BACKGROUND: In the United States, >50% of dietary calcium is provided by milk and milk products. Calcium intakes in the United States are inadequate for many children, and a large proportion do not drink milk or consume dairy products. However, no studies have addressed whether dairy-free diets can provide adequate calcium while meeting other nutrient recommendations. OBJECTIVE: To determine the highest calcium intake for adolescents obtained from dairy-free diets, and to examine the relationship between intakes of calcium-fortified foods, using citrus juice as an example, and maximal calcium intakes. DESIGN: In the National Health and Nutrition Examination Survey 2001 to 2002, 65 females and 62 males, aged 9 to 18 years, reported no intake of dairy. We used linear programming to generate diets with maximal calcium intake, while meeting Dietary Reference Intakes for a set of nutrients, limiting energy and fat intakes, and not selecting food quantities exceeding amounts usually eaten in the population. RESULTS: With food use and energy and fat constraints, diets formulated by linear programming provided 1,150 and 1,411 mg/day of calcium for girls and boys, respectively. With the Dietary Reference Intakes constraints, these decreased to 869 and 1,160 mg/day. When we introduced 1.5 servings of fortified juice to the diets, the highest calcium intake increased to 1,302 mg/day for girls and to 1,640 mg/day for boys. CONCLUSIONS: Adequate intake for calcium cannot be met with dairy-free diets while meeting other nutrient recommendations. To meet the adequate intake for calcium without large changes in dietary patterns, calcium-fortified foods are needed. In addition, greater physical activity and responsible sunlight exposure should be encouraged to promote vitamin D adequacy.     

Meeting calcium recommendations during middle childhood reflects mother-daughter beverage choices and predicts bone mineral status

BACKGROUND: Longitudinal data regarding the influence of beverage intakes on calcium adequacy are lacking. OBJECTIVE: This study evaluated calcium intake from ages 5 to 9 y as a function of mother-daughter beverage choices and as a predictor of bone mineral status. DESIGN: Intakes of energy, calcium, milk, sweetened beverages, fruit juices, and non-energy-containing beverages were measured with the use of three 24-h dietary recalls in 192 non-Hispanic white girls aged 5, 7, and 9 y and their mothers. Calcium intakes from ages 5 to 9 y were categorized as either meeting or falling below recommended adequate intakes (AIs). The girls' bone mineral status was assessed with dual-energy X-ray absorptiometry at age 9 y. RESULTS: The mean 5-y calcium intake was related to bone mineral density at age 9 y (beta = 0.27, P < 0.001). The girls who met the AI for calcium were not heavier (P = 0.83) but had higher energy intakes (P < 0.0001) than did the girls who consumed less than the AI. Compared with the girls who consumed less than the AI, the girls who met the AI consumed, on average, almost twice as much milk (P < 0.0001), had smaller decreases in milk intake (P < 0.01), and consumed 18% less sweetened beverages (P < 0.01) from ages 5 to 9 y; the 2 groups did not differ significantly in juice and non-energy-containing beverage intakes. The girls who met the AI were also served milk more frequently than were the girls who consumed less than the AI (P < 0.0001) and had mothers who drank milk more frequently (P < 0.01) than did the mothers of the girls who consumed less than the AI. CONCLUSIONS: These findings provide new longitudinal evidence that calcium intake predicts bone mineral status during middle childhood and reflects mother-daughter beverage choice patterns that are established well before the rapid growth and bone mineralization observed in adolescence.     

绝经后妇女钙摄入量及膳食来源分布

为了解绝经后妇女膳食钙的摄入量,钙的食物来源以及膳食结构,对济南市区154名绝经后妇女进行了7d膳食调查及24h尿钙测定.膳食调查采用记录和称重相结合的方法,用原子吸收分光光度法测定尿钙,依据《食物成份表》计算12类食物的平均摄入量以及钙在各类食物中的分布,对膳食钙摄入量与尿钙排出量进行相关分析.结果显示,济南市区绝经后妇女平均每天膳食钙摄入量为349±112mg,占RDA的44%,奶类和豆类食品虽然钙含量丰富,但摄入量较少.在被调查者中,18%的人钙摄入量不足200mg/d,66%的人不足400mg/d,仅有6%的人大于800mg/d,24h尿钙排出量平均258±83mg/24h,占膳食摄入钙的74%,膳食摄入钙与尿钙排出量无显著相关性(r=0.018,P>0.05).建议绝经后妇女增加奶和豆类食品的摄入量或摄入适量的钙补充剂以使钙的摄入量(RDA)不低于1000～1200mg/d.