Serum 25-hydroxy cholecalciferol in infants and preschool children in the Western region of Saudi Arabia. Etiological factors.

OBJECTIVE: Low vitamin D status has been frequently reported among Saudi subjects of all ages. No attempt has been made to relate this status to dietary intake or to diseases leading to malabsorption, for example diarrhea. This study was performed to investigate the various factors leading to low vitamin D status, and their relative importance in infants and preschool children. METHODS: Nine hundred and thirty-five healthy subjects aged 4-72 months were selected randomly form the Jeddah area of the Kingdom of Saudi Arabia. Medical history, time and frequency of exposure to sunlight and dietary intake were recorded. Blood samples were obtained form 739 subjects for the determination of 25-hydroxy cholecalciferol. The Subjects were divided into 5 age groups. The mean +/- standard deviation and other statistical parameters for serum 25-hydroxy cholecalciferol were calculated. Mean +/- standard deviations of exposure time and vitamin D intake were calculated, and subjects divided according to the adequacy of their intake. RESULTS: Age had no effect on the mean serum 25-hydroxy cholecalciferol (p=0.63). Mean dietary intake of the vitamin increased initially (p<0.05), decreased in the next group (p<0.005), then remained constant. There was significant correlation between serum level and dietary intake of the vitamin. No exposure to sunlight was noted in the youngest group. Low serum levels were associated mainly with repeated diarrheal attacks. This was the same in the next group. The mean exposure time in the 3rd group increased significantly (p<0.001). Low serum levels were found in subjects with low exposure time plus either or both of low dietary intake and repeated attacks of diarrhea. Increased mean exposure time (p<0.0005), and decreased incidence of repeated diarrheal attacks were found in the next age group with low serum levels noted in subjects with low exposure time and low dietary intake. In the oldest age group, mean exposure time increased further (p<0.0005), and low levels were found in subjects with low exposure time (mainly girls). CONCLUSION: Diet was the major source of the vitamin in subjects <12 months of age, and hence low levels were associated with frequent diarrheal attacks. A decrease in dietary intake, and more dependence on endogenous vitamin synthesis was apparent in older children, leading to low vitamin status in ones with low dietary intake and inadequate exposure to sunlight