The Vitamin D Connection to Pediatric Infections and Immune Function

Abstract

ABSTRACT:Over the past 20 y, a resurgence in vitamin D deficiency and nutritional rickets has been reported throughout the world, including the United States. Inadequate serum vitamin D concentrations have also been associated with complications from other health problems, including tuberculosis, cancer (prostate, breast, and colon), multiple sclerosis, and diabetes. These findings support the concept of vitamin D possessing important pleiotropic actions outside of calcium homeostasis and bone metabolism. In children, an association of nutritional rickets with respiratory compromise has long been recognized. Recent epidemiologic studies clearly demonstrate the link between vitamin D deficiency and the increased incidence of respiratory infections. Further research has also elucidated the contribution of vitamin D in the host defense response to infection. However, the mechanism(s) by which vitamin D levels contribute to pediatric infections and immune function has yet to be determined. This knowledge is particularly relevant and timely, because infants and children seem more A fter the discovery that vitamin D deficiency is the cause of nutritional rickets, the emphasis on vitamin D status in children was relegated to a discussion primarily focused on prevention and treatment of the disease. A few early clinicians, however, astutely recognized the increased incidence of respiratory infections among infants and children with rickets. Most presumed, however, that the increased incidence of respiratory infections in these children reflected compromised lung compliance from the rib deformities associated with severe rickets and an overall poor nutritional status. Now epidemiologic studies have identified a link between inadequate vitamin D concentrations and infectious disease. Furthermore, the contribution of vitamin D in host defense against infection has been elucidated. The goal of this study is to provide an overview on the current knowledge available regarding the role of vitamin D in immunologic function and the manifestations of infectious diseases in the pediatric population. Delineating Vitamin D Sufficiency, Insufficiency, and DeficiencyBy definition, vitamin D is not a true vitamin because adequate exposure to sunlight either negates or significantly diminishes the need for dietary supplementation. Instead, this imprecise descriptor refers to a group of steroid molecules also encompassing both vitamin D2 (derived from plants that use ergosterol rather than cholesterol) and vitamin D3 molecules (derived from cholesterol). The human body thus procures vitamin D through two independent pathways: the photochemical action of solar UVB light (ϳ295 to 320 nm) in the skin and some limited dietary sources (1).Given that vitamin D2 is produced by plants, dietary sources (naturally occurring and/or obtained via oral supplementation) are the only means for acquiring it. Vitamin D3, on the other hand, is predominantly procured via the sunlight driven cutaneous reaction described earlier or from dietary sources. For a...

The Effect of Vitamin D Deficiency on the Severity of Bronchiolitis in Infants

“…The relationship between vitamin D and asthma has been known for a long time. Although the mechanism is not known, new studies have found an association between high vitamin D levels and better lung functions, lower respiratory tract hypersensitivity and increased glucocorticoid responses (17).…”

T cell priming: let there be light

“…There is also evidence for an inverse correlation between URI incidence and 1,25(OH) 2 D3 serum levels, regardless of season [7]. Vitamin D has been also shown to have effects on the innate immune response, inhibiting proliferation of Mycobacterium tuberculosis in macrophages [6], and the majority of M. tuberculosis patients has low levels of serum vitamin D, supplementation of which results in greater clinical improvement than standard therapy alone [8]. Other studies have suggested a link between vitamin D insufficiency and autoimmune diseases such as multiple sclerosis and Crohn's disease [6] which may possibly be because vitamin D3 enhances Th2 differentiation at the expense of Th1 cells [9].…”

Association of serum vitamin D levels and transient tachypnea of newborn: a case control study

“…23 Vitamin D status during pregnancy also has strong correlation with innate immune response of fetus. 24 Vitamin D plays important role in prevention of respiratory diseases like respiratory distress syndrome, pneumonias, wheezing episodes, asthma in later life. Vitamin D also has a role in prevention of acute lower respiratory infections in toddlers.…”