The Research Of Vitamin D Nutritional Status Aged0to14years In Summer In Shijiazhuang

Objective: Traditionally, vitamin D as a fat-soluble vitamin regulatescalcium and phosphorus metabolism, acting on the skeletal organ system.However, along with the deepening of research, vitamin D, as a steroidhormone, has been shown to have extensive biological functions, in relation tothe endocrine system, cardiovascular disease, and nervous system, immuneand other aspects. World-wide attention is focused on the importance ofvitamin D in optimizing health and preventing disease［1］.Vitamin D deficiencyis pandemic on a global scale, including all ages, genders and racial/ethnicgroups［2］. The overall level is influenced by many factors including seasonalchanges, diet, activities and drugs, etc. In the sunny summer, thedermal production of vitamin D increases following the sun exposure and thelevel of vitamin D is concerned to be adequate and highest. Currently, thelarge-scale study of vitamin D status is seldom in China. The lack of sufficientdata is difficult to determine the most safe and efficacious approach tovitamin D supplementation in our children, especially older children. Thepurpose of the study was to survey the levels of serum25-hydroxyvitamin D[25（OH） D] and closely related to the levels of parathyroid hormone （PTH）,aged0to14years in summer, in Shijiazhuang area （38:03N）, the capital ofHebei Province, to learn about the vitamin D nutritional status in children, todiscuss the effects of obesity, various feeding ways, sun exposure and otherfactors. The study is to provide reliable data for the recommendation forreasonable vitamin D supplementation in China.Methods: From June to August in2011, recruit volunteers aged0to14years for health examination in Shijiazhuang through the Yanzhao MetropolisDaily,403in all, including247boys and156girls. According to their agewere divided into five subgroups:0-1y,1-3y,3-7y,7-10y and10-14y. On the basis of BMI^［3］, the children are classified as four groups: Under weight,Normal, Over weight and Obesity. This study is a cross-sectional study.1The questionnaire survey: the content includes: birth history, feeding ways,total dairy intake, vitamin D or calcium supplement, the time for outdooractivities and Past History.2The medical examination: the specialists areresponsible for measuring the length or height, body weight, calculating bodymass index （BMI）.3Indexes measurement: collect4ml fasting vein blood,anticoagulation. All samples have been taken between8-10am and centrifugedat2000r/min for15min after stored at room temperature for30-40min.theserum were stored at-20centigrade for test. Serum25（OH） D is measured byEnzyme-linked immune method （ELISA） and parathyroidhormone （PTH） ismeasured by Chemiluminescence （CLIA）.4The defining standard:①Severedeficiency:<12.5nmol/L;②Moderate deficiency（12.5-25nmol/L）:≥12.5nmol/L,and＜25nmol/L.③Mild deficiency（25-50nmol/L）:≥25nmol/L,and＜50nmol/L;④Insufficient（50-75nmol/L）:≥50nmol/L,and＜75nmol/L;⑤Adequate（75-250nmol/L）:≥75nmol/L, and＜250nmol/L;⑥Excess（250-375nmol/L）:≥250nmol/L, and＜375nmol/L;⑦Intoxication:≥375nmol/L.5Statistical recordsanalysis: data follows normal distribution with mean±standard devia-tion, orelse, with median （interquartile range）. All the data is analyzed by SPSS13.0software.Results:1All the subjects, the mean level of serum25（OH） D is59.05（39.93） nmol/L. The level of each age group is respectively86.10±36.43nmol/L,84.30（38.06） nmol/L,58.78（26.40） nmol/L,44.45±16.42nmol/L,35.25（19.61） nmol/L. Generally, vitamin D levels decrease gradually with thegrowth of the ages, with a significant negative correlation.（r=-0.678, P <0.05）. The highest was found in the0-1y and1-3y, the lowest one was foundin10-14y.67.99%children’s serum25（OH） D levels are in the vitamin Dinsufficiency and even deficiency states.2The average serum25（OH） D levelof boys were57.28（41.78） nmol/L, compared with girls61.75（37.04） nmol/L,there was no statistical difference between them （P>0.05）. It shows that25（OH） D levels did not correlate to gender.30-1y group, according to different feeding ways were divided into breastfeeding and mixed or artificial feedinggroups, the average serum25（OH） D level was respectively75.53±40.13nmol/L,94.91±51.08nmol/L, there was no statistical difference betweenthem（P>0.05）. Feeding mode showed no relationship with25（OH） D levels.4All the samples were grouped by added vitamin D or not, the supplementswhich is taking vitamin D orally regularly on average of200-600IU/d,persisted for more than1month. Serum25（OH） D level of non supplementgroup were52.35（34.11）nmol/L，significantly lower than the supplement,which was90.45（50.55）nmol/L, with significant statistical difference （P <0.05）. Vitamin D supplements with oral can obviously improve the level ofserum25（OH） D.5According to the time for outdoor activities, all childrenwere divided into3subgroups, less than0.5h,0.5-2h,more than2h. There aresignificant differences among the groups （P＜0.05）, which is positivelycorrelated with time （r=0.519, P <0.05）, markedly increased with longerhours. And we observed the time spent outdoor decreases gradually with age（P <0.05）.6The four groups: Normal, Over weight and Obesity, the meansare64.61（37.84） nmol/L,59.09（40.82） nmol/L,60.78±28.92nmol/L,46.03（34.73） nmol/L respectively, obesity group compared with normal group andthe under weight group, the serum25（OH） D levels significantly reduced （P <0.05）, while among other groups,25（OH） D levels had no obvious difference.Bivariate correlation analysis indicated that serum25（OH） D and wasnegatively correlated with PTH （r=-0.294, P <0.05）, and BMI （r=-0.282, P<0.05）.Conclusion:1The prevalence of vitamin D deficiency and insufficiencyamong children in our country is high, and vitamin D levels gradually declinewith age, so after the age of three, vitamin D supplementation should bestrengthened and necessarily extended to adolescences, even to adults. Inaddition, gradually increasing the time of sun exposure, especially forschool-aged children and adolescence, is beneficial to produce vitamin D;vitamin D level should be improved.2Obesity is closely related to thedecreasing vitamin D levels, fat person serum25（OH） D levels significantly lower than the normal.3Serum25（OH） D is closely related to parathyroidhormone and body mass index.The measurement of these indicators can helpvitamin D nutritional status evaluation.