A survey of Vitamin D level and the rate of Vitamin D supplementation in infants and young children in Tianjin

Objective To investigate the Vitamin D levels of 3 030 infants and young children and the application rate of Vitamin D supplements.To evaluate the nutritional status of Vitamin D and to find out the problems in the application of Vitamin D supplements. Methods Enzyme linked immunosorbent assay was used to determine the level of 25-hydroxyvitamin D[25(OH)D] in all the subjects.The subjects were divided into 4 groups according to their ages: ≤6 months, >6-12 months, >12-24 months, >24-36 months.The average levels of Vitamin D in different ages and seasons were compared.Three hundred and forty-one cases were randomly selected to undergo a parent questionnaire survey and a laboratory test including hemoglobin (Hb) and bone alkaline phosphatase (BALP). The association of 25(OH)D level with feeding methods, gestational age, birth weight, Hb, and BALP were compared. Results The average level of 25(OH)D was (60.2±26.2) nmol/L with the minimum of 12.9 nmol/L and the maximum of 286.0 nmol/L.The total deficiency rate was 36.6%(1 109/3 030 cases), and young children who were >24-36 months old had the lowest level of 25(OH)D[(47.22±21.93) nmol/L](F=50.006, P<0.01). The levels of Vitamin D in autumn were(62.00±27.42) nmol/L, which were significantly higher than those in other seasons (F=2.750, P<0.05). The levels of 25 (OH) D in preterm infants were (62.00±27.42) nmol/L, which were significantly lower than those in full term infants (F=12.355, P<0.01). The application rate of Vitamin D supplements was 97.1%(331/341 cases). Conclusions Although the application rate of Vitamin D supplementation in infants and young children is very high, there is still a certain proportion of Vitamin D deficiency.This may be because of the poor compliance of the supplementary process.Therefore, it is necessary to strengthen the publicity and education and improve the parental cognition and recognition.During pregnancy and age after birth, effective monitoring mechanism of Vitamin D levels and the application of Vitamin D supplements should be considered into the existing maternal and child health care system. Key words: Infants and young children; Vitamin D deficiency; 25-hydroxyvitamin D