Vitamin D and airway infections: a European perspective

Abstract

Vitamin D has immuno-modulatory properties, and deficient levels of circulating 25-hydroxyvitamin D (<30 nmol/l) may contribute to increased risk of infectious illnesses. This narrative review summarises data on vitamin D status in Europe and updates results of randomised controlled trials (RCTs) regarding vitamin D and airway infections such as tuberculosis (TB) and acute upper respiratory tract infection. In Europe, the prevalence of vitamin D deficiency is up to 37 % in the general population and up to 80 % in nursing home residents and non-European immigrants. Half of TB patients have a migration background. While results of RCTs do not support the concept of beneficial adjunctive effects of vitamin D supplements in anti-TB treatment [odds ratio (OR) = 0.86; 95 % CI 0.62–1.19], the few published RCTs on the prophylaxis of TB suggest some protective vitamin D effects in individuals with deficient circulating 25-hydroxyvitamin D levels. Regarding acute respiratory tract infection, RCTs indicate a significant risk reduction by vitamin D supplements [OR = 0.65; 95 % confidence interval (CI) 0.50–0.85]. There is evidence that daily administration is more effective than high-dose bolus administration [OR = 0.48 (95 % CI 0.30–0.77) vs. OR = 0.87 (95 % CI 0.67–1.14)] and that individuals with deficient or insufficient (30–50 nmol/l) circulating 25-hydroxyvitamin D levels benefit most. Several vitamin D effects on innate immunity may explain these protective effects. In summary, there is possible evidence from RCTs for protective vitamin D effects on TB and likely evidence for protective effects on acute airway infection. Since vitamin D deficiency is prevalent in Europe, especially in institutionalised individuals and non-European immigrants, daily oral vitamin D intake, e.g. 1000 international units, is an inexpensive measure to ensure adequate vitamin D status in individuals at risk.

Vitamin D Promotes Pneumococcal Killing and Modulates Inflammatory Responses in Primary Human Neutrophils

“…Vitamin D deficiency is associated with a range of bacterial infections [30] in humans, particularly with pneumonia [15] . However, the effects of vitamin D on neutrophils, which are the major inflammatory cells during pneumococcal infections, remain largely unknown.…”

Non-classical effects of vitamin D

“…Имеются данные, поддержи-вающие возможную роль дефицита витамина D в раз-витии туберкулеза у детей, рецидивирующего острого среднего отита и тяжелого бронхиолита, тогда как связь с рецидивирующим фаринго-тонзиллитом, острым ри-носинуситом и внебольничной пневмонией требует под-тверждения [33]. Мета-анализы проведенных РКИ указы-вают на снижение заболеваемости туберкулезом и ОРВИ при приеме препаратов витамина D среди взрослых, особенно при ежедневных режимах приема и среди лиц с низкими уровнями 25(OH)D [34,35].…”

“English Disease”: Historical Notes on Rickets, the Bone–Lung Link and Child Neglect Issues

“…In the last two decades, an intense investigation around Vitamin D and its metabolism has been recorded identifying its important roles in cell signaling during both the adaptive and innate immune response to bacterial and viral infections [30,31,32,83,84,85,86,87,88,89,90]; for example, cholecalciferol in the management of tuberculosis (TB) [14,91,92]. In addition to the conventional T, B, and natural killer (NK) cells, there is a group of recently recognized innate lymphoid cells (ILCs) involved in mediating the host defense [93].…”

“…About 43% of 200 Iranian children admitted to the hospital with radiographically proven rickets had classic signs of bronchopneumonia [116], about half of 250 Kuwaiti children with rickets had pneumonia or bronchopneumonia [117], and even four out of five of Egyptian children with rickets showed acute respiratory infections at some point during hospitalization [118]. As mentioned earlier, this association between rickets and pneumonia may be explained by the effects of 1,25(OH) 2 D 3 on the immune system, because calcitriol stimulates phagocyte-dependent and antibody-dependent macrophage cytotoxicity modulating simultaneously T and B cell function [30,31,32,83,84,85,86,87,88,89,90]. …”

“…More recently, the link between Vitamin D deficiency and impaired immunity, inflammatory response and dysregulated cancer pathways has been emphasized [27,28,29]. In fact, immune system cellular components possess Vitamin D receptors (VDRs) that can bind the active form of Vitamin D (calcitriol, 1,25-dihydroxyVitamin D, 1,25(OH) 2 D) [30,31,32,33]. The storage form of Vitamin D, which is 25-hydroxyvitamin D, or 25(OH)D, can be converted by activated T and B cells to 1,25(OH) 2 D in human cells in vitro [34].…”