25-Hydroxyvitamin D: functional outcomes in infants and young children

Abstract

Vitamin D deficiency occurs in the United States in exclusively breastfed infants who have high levels of skin pigmentation, inadequate vitamin D supplementation, and insufficient sunlight exposure. I review serum 25-hydroxyvitamin D [25(OH)D] concentrations and functional outcomes of vitamin deficiency in young children and breastfed and nonbreastfed infants. These outcomes include the presence or absence of vitamin D deficiency rickets, bone mineral content, and serum parathyroid hormone concentration. Daily vitamin D supplements of 400 IU/L keep serum 25(OH)D concentrations higher than 50 nmol/L and prevent rickets in infants and young children. The available evidence is not sufficient to support the use of bone mineral content or parathyroid hormone concentrations in infants and young children as functional outcomes to define deficient or sufficient levels of 25(OH)D. I therefore propose a research agenda to establish the functional definitions of vitamin D sufficiency or deficiency in infants and young children.Am J Clin Nutr 2008;88(suppl):529S-33S. INTRODUCTIONThe typical US diet contains few natural sources of vitamin D other than fatty fish and liver, which are foods not common in the diets of infants younger than 12 mo of age or young children aged 1-5 y. All US formulas for infants contain ͧ400 IU of vitamin D/L. Thus, infants who consume ͧ500 mL of formula per day receive 200 IU/d. The Institute of Medicine (1) considers this level adequate, but this is less than the 400 IU/d that the American Academy of Pediatrics (AAP; 2) and the Canadian Pediatric Society (3) currently recommend for infants and young children. For infants exclusively fed human milk, which has very little vitamin D (Ȃ22 IU/L; 4), the AAP recommends a vitamin D supplement of ͧ400 IU/d, but many breastfed infants in the United States do not take vitamin D supplements (2).The skin naturally produces vitamin D from the reaction of sunlight (ultraviolet B irradiation) with 7-dehydrocholesterol; however, the multitude of variables that affect skin synthesis of vitamin D make it difficult to recommend a specific amount of sunlight exposure for all infants and young children (2). Furthermore, because of the relation of sun exposure to skin cancer, the Centers for Disease Control and Prevention, with the support of many organizations (including the AAP, the American Academy of Dermatology, and the American Cancer Society), has launched a campaign to increase public awareness about sunlight exposure and the risks of various skin cancers (5). Moreover, the AAP and the American Academy of Dermatology recommend that infants younger than 6 mo not be exposed to the sun and that all children and adolescents use sunscreens and clothing to protect them from ultraviolet B radiation exposure and to prevent skin cancer (6).Newborn infants have a unique source of vitamin D: the mother, who transfers vitamin D to the fetus across the placenta (Figure 1 25-HYDROXYVITAMIN D CONCENTRATIONS IN NEWBORNSAccording to numerous investigators, 25(OH)D con...

Vitamin D status in infants: relation to nutrition and season

“…Selection bias may likely explain the high frequency of vitamin D supplementation. Despite the high frequency of supplementation, a longer period of exclusive breastfeeding and breastfeeding at 9 months were both significantly associated with lower levels of 25(OH)D. We found that the dietary intake of vitamin D was positively associated with 25(OH)D. The intake did also include infant formula and enriched commercial baby foods, whereas it did not include the content of vitamin D in breast milk, which is, on the other hand, known to be low (Greer, 2008). In all, 92% of the infants who were not breastfed at 9 months received infant formula, indicating that breast milk replaces an energy intake from more vitamin D-rich sources.…”

“…What defines an optimal concentration of 25(OH)D in children is an important question, but consensus has not been reached (Vieth, 2006;Wagner and Greer, 2008). Breastfeeding without vitamin D supplementation is a predictor of vitamin D deficiency (Gordon et al, 2008;Greer, 2008). Only 7 out of 255 infants did not receive vitamin D supplements during the first 9 months.…”

“…In all, 92% of the infants who were not breastfed at 9 months received infant formula, indicating that breast milk replaces an energy intake from more vitamin D-rich sources. Infants are recommended not to stay in direct sunlight because of skin cancer risk (Greer, 2008); nevertheless, there was a seasonal difference in 25(OH)D, with higher levels in sunny months than in winter months. In conclusion, nearly all of the infants received vitamin D supplementation at the age of 9 months and 89% of the infants had sufficient levels of 25(OH)D. The present study indicates that infants receiving the recommended daily amount of vitamin D have a sufficient vitamin D status.…”

Using data from a multi-hospital clinical network to explore prevalence of pediatric rickets in Kenya

“…Vitamin D is also synthesized when human skin is exposed to sunlight; dark skin synthesizes vitamin D at a slower rate 6 . Therefore, children in low income sub-Saharan Africa countries are perhaps paradoxically some of the most susceptible to rickets 7, 8 .…”

Assessment of vitamin D level in the umbilical cord blood of the Arkhangelsk city infants born in winter time

“…Плацен-та играет огромную роль в превращении 25(OH)D в 1,25(OH) 2 D (который не способен проникать че-рез плаценту) за счет активности 1α-гидроксилазы, благодаря чему возможно увеличение содержания 1,25(OH) 2 D у матери и плода до 2 раз [8][9][10]. По-вышенная концентрация 1,25(OH) 2 D способствует снижению уровня провоспалительных цитокинов, предотвращает развитие преэклампсии и прежде-временные роды, участвует в регуляции секреции половых гормонов (эстрадиола и прогестерона) [11,12]. После родов отмечается значительное сни-жение уровня 25(OH)D и 1,25(OH) 2 D.…”