Vitamin D Status and Seasonal Variation among Danish Children and Adults: A Descriptive Study

Bone mineral density and vitamin D in paediatric intestinal failure patients receiving home parenteral nutrition

BACKGROUND & AIMS

Patients with intestinal failure (IF) are dependent on long-term home parenteral nutrition (HPN) to ensure growth and development. The primary aim of the present study was to assess bone mineral density (BMD) and vitamin D status in paediatric IF patients on HPN and a group of healthy children aged 2-18 years. Secondary aims were to assess growth, body composition, nutrient provision and physical activity.

METHODS

An observational cross-sectional study was performed at Oslo University Hospital and at the Department of Nutrition, University of Oslo, from January to September 2017. Dual energy x-ray absorptiometry (DXA; Lunar Prodigy in IF patients and Lunar iDXA in healthy subjects) was performed to assess BMD and body composition. BMD z-score (BMDz) was calculated for total body and lumbar spine L2-L4 based on the integrated reference population in the software. Weight and height were measured for growth assessment. Nutrient provision was assessed by a 4-day food record. Blood samples were analysed for 25-hydroxy-vitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D). Physical activity was reported by a questionnaire.

RESULTS

Nineteen IF patients and 50 healthy children were included. The mean age of participants was 10.0 years. The aetiology of IF patients was paediatric intestinal pseudo-obstruction (58%), short bowel syndrome (26%), and intestinal enteropathy (16%). Lower median BMDz for total body (-0.4 vs 1.1, P < 0.001) and lumbar spine L2-L4 (-0.9 vs 0.2, P = 0.01) were found in the IF group compared with the healthy children. Vitamin D provision was significantly higher in IF patients (17 μg/d vs 5.3 μg/d, P < 0.001). Both groups were sufficient in 25(OH)D (IF patients 71 nmol/L vs healthy 81 nmol/L). Nevertheless, IF patients had significantly lower 1,25(OH)₂D than healthy children (71 pmol/L vs 138 pmol/L, P < 0.001). The IF group was significantly shorter (height for age z-score -1,5 vs 0,1, P = 0.001) and lighter (weight for age z-score -1,0 vs 0,1, P = 0.009) compared with the healthy subjects. BMIz did not differ; however, body fat percentage was significantly higher in IF patients compared with healthy children (34% vs 25%, P = 0.02). A lower frequency of physical activity was found in the IF group compared with the healthy group (P = 0.001).

CONCLUSIONS

Paediatric IF patients on HPN had lower BMD, impaired growth, and higher body fat percentage in comparison with the healthy children. Despite a higher total supply of vitamin D in the IF group, the levels of 25(OH)D did not differ. Nevertheless, a significantly lower level of 1,25(OH)₂D was found in IF patients. The results raise questions regarding differences between oral and parenteral vitamin D provision and whether intestinal function is important for the metabolism of vitamin D.

TRIAL IDENTIFICATION NUMBER

Clinical Trials AEV2017/1. 2016/391/REK sør-øst B REVISION NUMBER: CLNESP-D-20-00022.

Evaluating Vitamin D levels in Rheumatic Heart Disease patients and matched controls: A case-control study from Nepal

Background

Diagnosis and treatment for Rheumatic Heart Disease (RHD) is inaccessible for many of the 33 million people in low and middle income countries living with this disease. More knowledge about risk factors and pathophysiologic mechanisms involved is needed in order to prevent disease and optimize treatment. This study investigated risk factors in a Nepalese population, with a special focus on Vitamin D deficiency because of its immunomodulatory effects.

Methods

Ninety-nine patients with confirmed RHD diagnosis and 97 matched, cardiac-healthy controls selected by echocardiography were recruited from hospitals in the Central and Western region of Nepal. Serum 25(OH)D concentrations were assessed using dried blood spots and anthropometric values measured to evaluate nutritional status. Conditional logistic regression analysis was used to define association between vitamin D deficiency and RHD.

Results

The mean age of RHD patients was 31 years (range 9–70) and for healthy controls 32 years (range 9–65), with a 4:1 female to male ratio. Vitamin D levels were lower than expected in both RDH and controls. RHD patients had lower vitamin D levels than controls with a mean s-25(OH)D concentration of 39 nmol/l (range 8.7–89.4) compared with controls 45 nmol/l (range 14.5–86.7) (p-value = 0.02). People with Vitamin D insufficiency had a higher risk (OR = 2.59; 95% CI: 1.04–6.50) of also having RHD compared to people with Vitamin D concentrations >50 nmol/l. Body mass index was significantly lower in RHD patients (22.6; 95% CI, 21.5–23.2) compared to controls (24.2; 95% CI, 23.3–25.1).

Conclusion

RHD patients in Nepal have lower Vitamin D levels and overall poor nutritional status compared to the non-RHD controls. Longitudinal studies are needed to explore the causality between RHD and vitamin D level. Future research is also recommended among Nepali general population to confirm the low level of vitamin D as reported in our control group.

Serum 25 hydroxyvitamin D levels and affecting factors among preconception fertile women

Background

Recent study found that vitamin D before conception was considered as a potential additional determinant for achieving pregnancy and live births. The study aimed to evaluate the serum 25 hydroxyvitamin D (25(OH)D) levels and its affecting factors among preconception fertile women.

Methods

This cross-sectional study enrolled 410 women aged 22–44 years who attended a preconception genetic counseling clinic from January 2018 to May 2019. Sociodemographic characteristics and reproductive history of women were collected, and height and weight were measured. Serum 25(OH)D concentration was assayed with chemiluminescence immunoassay. Descriptive statistics were used to examine serum 25(OH)D concentration, and socio-demographic characteristics and reproductive history among preconception women. Determinants of vitamin D deficiency and its affecting factors were assessed using χ2 test and logistic regression.

Results

Findings showed 84.4% of women had serum 25(OH)D concentration below 20 ng/mL. Women working indoors as well as without a history of childbirth had significantly lower 25(OH)D levels compared with those non-working individuals and having delivered a previous child (both P < 0.05). The 25(OH)D levels were the lowest in winter among that in spring, summer, and autumn (all P < 0.001). Women in winter have significantly elevated OR of 5.00 (95%CI 1.75–14.25) to develop vitamin D deficiency. Seasonal variation in serum 25(OH)D levels was not present in non-working individuals and women aged 31–44 years.

Conclusions

Vitamin D deficiency is common among preconception women especially nulliparous women and working women, which propose to screen serum 25(OH)D on preconception evaluation and emphasize need vitamin D supplements and get sunshine exposure.

Circulating Levels of Muscle-Related Metabolites Increase in Response to a Daily Moderately High Dose of a Vitamin D3 Supplement in Women with Vitamin D Insufficiency-Secondary Analysis of a Randomized Placebo-Controlled Trial

Recently, we demonstrated negative effects of vitamin D supplementation on muscle strength and physical performance in women with vitamin D insufficiency. The underlying mechanism behind these findings remains unknown. In a secondary analysis of the randomized placebo-controlled trial designed to investigate cardiovascular and musculoskeletal health, we employed NMR-based metabolomics to assess the effect of a daily supplement of vitamin D3 (70 µg) or an identically administered placebo, during wintertime. We assessed the serum metabolome of 76 postmenopausal, otherwise healthy, women with vitamin D (25(OH)D) insufficiency (25(OH)D < 50 nmol/L), with mean levels of 25(OH)D of 33 ± 9 nmol/L. Compared to the placebo, vitamin D3 treatment significantly increased the levels of 25(OH)D (−5 vs. 59 nmol/L, respectively, p < 0.00001) and 1,25(OH)₂D (−10 vs. 59 pmol/L, respectively, p < 0.00001), whereas parathyroid hormone (PTH) levels were reduced (0.3 vs. −0.7 pmol/L, respectively, p < 0.00001). Analysis of the serum metabolome revealed a significant increase of carnitine, choline, and urea and a tendency to increase for trimethylamine-N-oxide (TMAO) and urinary excretion of creatinine, without any effect on renal function. The increase in carnitine, choline, creatinine, and urea negatively correlated with muscle health and physical performance. Combined with previous clinical findings reporting negative effects of vitamin D on muscle strength and physical performance, this secondary analysis suggests a direct detrimental effect on skeletal muscle of moderately high daily doses of vitamin D supplements.

Exposure to the Danish Mandatory Vitamin D Fortification Policy in Prenatal Life and the Risk of Developing Coeliac Disease-The Importance of Season: A Semi Ecological Study

Few studies have examined the role of maternal diet in relation to development of coeliac disease (CD). In Denmark, cancellation of mandatory vitamin D fortification of margarine in June 1985 provided this opportunity. This study examined if season of birth or prenatal exposure to extra vitamin D from food fortification were associated with developing CD later in life. A strength of this study is the distinctly longer follow-up of patients (30 years). This register-based study has a semi-ecological design. Logistic regression analysis was used to estimate odds ratios and to calculate 95% confidence intervals. The odds ratio for developing CD was 0.81 (95% CI 0.66; 1.00 p = 0.054), comparing those with fetal exposure to mandatory vitamin D fortification policy of margarine to those without after adjusting for gender and season of birth. There was a statistically significant season effect particularly for children born in autumn (OR 1.6 95% CI 1.16; 2.21) and born in summer (OR 1.5 95% CI 1.1; 2.1) when compared to children born in winter. Although this study did not find evidence to support the premise that prenatal exposure to small extra amounts of vitamin D from a mandatory food fortification policy lowered risk of developing CD, the small number of CD cases and observed association between season of birth and CD suggest that environmental exposure ought to be further explored.

Serum 25 hydroxyvitamin D levels in alopecia areata, female pattern hair loss, and male androgenetic alopecia in a Chinese population

BACKGROUND

It has been suggested that low vitamin D levels may affect the development of hair loss.

AIMS

Our aim was to evaluate the serum 25-hydroxy vitamin D [25(OH)D] status in Chinese patients with alopecia areata (AA), female pattern hair loss (FPHL), and male androgenetic alopecia (MAGA) compared with healthy individuals.

METHODS

We performed a case-control study including 443 AA patients, 657 FPHL patients, 777 MAGA patients, and 2070 normal controls (1064 male and 1006 female healthy individuals) from 2015 to 2017 to analyze the correlation of serum 25(OH)D levels and hair loss in a Chinese population.

RESULTS

Serum 25(OH)D levels stratified by age, sex, and season were compared between patients and healthy individuals. AA patients' serum 25(OH)D levels were statistically lower than that of controls (P < .0001, α = .05). Serum 25(OH)D levels of FPHL patients (P < .0001, α = .05) and MAGA patients (P = .0005, α = .05) were also significantly lower than counterpart control subjects.

CONCLUSION

Our findings suggest an association between serum 25(OH)D levels and alopecia areata, female pattern hair loss, or male androgenetic alopecia in a Chinese population.

Status and influential factors of vitamin D among children aged 0 to 6 years in a Chinese population

BACKGROUND

Vitamin D insufficiency and deficiency in childhood are common. However, the status and influential factors of vitamin D during different ages are not clear. This study aimed to survey vitamin D concentrations in children aged 0 to 6 years and explore its influential factors.

METHODS

A total of 6953 children were recruited in Wuxi City of East China from January to December in 2016. Enzyme-linked immunosorbent assay was used to determine the serum concentrations of 25-hydroxyvitamin D [25(OH)D].

RESULTS

The median vitamin D concentrations in the infant group (0-1 years of age) was 69.40 nmol/L, which were higher than that in both the toddlerhood group (1-3 years of age; 62.30 nmol/L) and the preschool group (3-6 years of age; 50.85 nmol/L). In addition, the median vitamin D concentrations were 71.70 nmol/L in summer, which was higher than that in spring (64.25 nmol/L), autumn (62.95 nmol/L) and winter (64.10 nmol/L). However, no difference was observed between genders (P = 0.974). Furthermore, the prevalence of vitamin D deficiency (< 50 nmol/L) was 48.1% in the preschool group (3-6 years of age), which was higher than the 21.2% vitamin D deficiency in the toddlerhood group (1-3 years of age) and the 17.9% vitamin D deficiency in the infant group (0-1 years of age). Interestingly, a nonlinear association between 25(OH) D and air temperature was observed.

CONCLUSIONS

A high prevalence of vitamin D deficiency was common in a Chinese population of children 0-6 years old, especially in the preschool-aged children. Therefore, we suggested that we should pay more attention to vitamin D supplementation in Chinese young children.

Environmental, Nutritional, and Socioeconomic Determinants of IBD Incidence: A Global Ecological Study

BACKGROUND AND AIMS

The wide variation in inflammatory bowel disease [IBD] incidence across countries entails an opportunity to recognise global disease determinants and hypothesise preventive policies.

METHODS

We fitted multivariable models to identify putative environmental, nutritional, and socioeconomic determinants associated with the incidence of IBD (i.e. ulcerative colitis [UC] and Crohn's disease [CD]). We used the latest available country-specific incidence rates, and aggregate data for 20 determinants, from over 50 countries accounting for more than half of the global population. We presented the associations with exponentiated beta coefficients (exp[β]) indicating the relative increase of disease incidence per unit increase in the predictor variables.

RESULTS

Country-specific incidence estimates demonstrate wide variability across the world, with a median of 4.8 new UC cases (interquartile range [IQR] 2.4-9.3), and 3.5 new CD cases [IQR 0.8-5.7] per 100 000 population per year. Latitude (exp[β] 1.05, 95% confidence interval [CI] 1.04‒1.06, per degree increase), prevalence of obesity [1.05, 1.02‒1.07, per 1% increase], and of tobacco smoking [0.97, 0.95‒0.99, per 1% increase] explained 71.5% of UC incidence variation across countries in the adjusted analysis. The model for CD included latitude [1.04, 1.02‒1.06], expenditure for health (1.03, 1.01‒1.05, per 100 purchasing power parity [PPP]/year per capita increase), and physical inactivity prevalence [1.03, 1.00‒1.06, per 1% increase], explaining 58.3% of incidence variation across countries. Besides expenditure for health, these associations were consistent in low/middle- and high-income countries.

CONCLUSIONS

Our analysis highlights factors able to explain a substantial portion of incidence variation across countries. Further high-quality research is warranted to develop global strategies for IBD prevention.

Development of a Danish Adapted Healthy Plant-Based Diet Based on the EAT-Lancet Reference Diet

Plant-based diets have been linked to both health benefits and a lower climate impact. However, plant-based diets may represent both healthy and unhealthy dietary practices. The present study aimed to develop a nationally adapted healthy plant-based diet based on the global EAT-Lancet reference diet. Development took place in a series of steps. First, the original EAT-Lancet reference diet was evaluated based on food availability, i.e., using Danish food data (Model 1). Then, the model was further modified to reflect national food based dietary guidelines (FBDG) and characteristics of current consumption pattern, e.g., by including processed food, discretionary foods and beverages in the diet (Model 2). The contents of macronutrients, vitamins and minerals, except for vitamin D and iodine, were found to be sufficient for Model 2, according to the recommended nutrient density to be used for planning diets for groups of individuals aged 6–65 years. In addition, the study gave an insight into the nutrients and foods to be aware of in planning a predominantly plant-based diet, thereby providing directions for future revisions of sustainable FBDGs. These include a stronger emphasis on the intake of legumes, nuts and seeds, fruit and vegetables including dark green vegetables, whole-grain products and vegetable oils as well as lowering meat intake.

Vitamin D status in an Australian patient population: a large retrospective case series focusing on factors associated with variations in serum 25(OH)D

OBJECTIVES

To investigate whether sex, age, medical specialty and seasonal variations in serum concentration of 25-hydroxy vitamin D (25(OH)D) are evident among an Australian patient population.

DESIGN

Retrospective study analysing the results of serum 25(OH)D lab tests and vitamin D supplementation from Royal Melbourne Hospital (RMH) between 2014 and 2017.

SETTING

Tertiary healthcare centre in Victoria, Australia.

PARTICIPANTS

30 023 patients (inpatient and outpatient) who had their serum 25(OH)D levels measured at RMH between 2014 and 2017.

MAIN OUTCOME MEASURES

Serum 25(OH)D levels stratified according to patients' sex, age and medical specialty admitted to, as well as the season and year (2014 to 2017) 25(OH)D level was measured.

RESULTS

Mean serum 25(OH)D level of study population was 69.9 nmol/L (95% CI 69.5 to 70.2). Only 40.2% patients in this cohort were sufficient in vitamin D (>75 nmol/L). On average, 25(OH)D levels in male patients were 6.1 units (95% CI 5.4 to 6.9) lower than in females. Linear regression analysis found that 25(OH)D levels increased by 0.16 unit (95% CI 0.14 to 0.18) for every year increase in age. One-way analysis of variance showed patients from neurology had the highest average 25(OH)D level, 76.8 nmol/L (95% CI 74.2 to 79.3) compared with other medical specialties. Mean 25(OH)D level during winter, 64.9 nmol/L (95% CI 64.2 to 65.6) was significantly lower compared with other seasons despite supplementation. Average 25(OH)D level measured in 2014, 71.5 nmol/L (95 CI% 70.8 to 72.2) was significantly higher than levels measured in 2016-2017.

CONCLUSIONS

There is a sex, age, medical specialty, seasonal and yearly variation in vitamin D status in an Australian patient population. The association between low vitamin D status and winter despite supplementation suggests other interventions are required to boost serum 25(OH)D levels.

Determinants of Vitamin D Supplementation among Individuals with Type 1 Diabetes

Half of the individuals with type 1 diabetes (T1DM) may present Vitamin D (VD) deficiency. There is little known about factors determining a decision on VD supplementation. The study aimed to determine the factors affecting vitamin D supplementation in people with T1DM. A cross-sectional survey study using the authors’ questionnaire paper and its digital version was performed. The questions involved data on the basic characteristics of the respondent, medical history, VD supplementation status, influence of the social environment, self-education, and the most important personal motivator for VD supplement use. Multivariate logistic regression analysis was performed. We collected a total of n = 184 papers and n = 550 digital complete surveys. From 734 total respondents, 62.0% declared VD supplementation. The main personal rationale for VD supplementation were recommendation of medical specialist 172 (37.8%) and self-education 135 (29.7%). The main reasons for non-supplementation of VD were lack of knowledge about VD 159 (57.0%) and lack of motivation 77 (27.6%). VD supplementation was independently associated with a family doctor (odds ratio (OR), 95% confidence interval (CI): 4.67, 2.32–9.40) or medical specialist recommendation (16.20, 9.57–27.43), and self-education (5.97, 3.90–9.13). Most Polish individuals with T1DM use VD supplements, and the decision is related to physicians’ recommendations and self-education.

Vitamin D status and current policies to achieve adequate vitamin D intake in the Nordic countries

Aims: Nordic countries share fairly similar food culture and geographical location as well as common nutrition recommendations. The aim of this paper was to review the latest data on vitamin D status and intake and to describe the national supplementation and food fortification policies to achieve adequate vitamin D intake in the Nordic countries. Methods: The data are based on results derived from a literature search presented in a workshop held in Helsinki in November 2018 and completed by recent studies. Results: Vitamin D policies and the implementation of the recommendations differ among the Nordic countries. Vitamin D fortification policies can be mandatory or voluntary and widespread, moderate or non-existent. Vitamin D supplementation recommendations differ, ranging from all age groups being advised to take supplements to only infants. In the general adult population of the Nordic countries, vitamin D status and intake are better than in the risk groups that are not consuming vitamin D supplements or foods containing vitamin D. Non-Western immigrant populations in all Nordic countries share the problem of vitamin D insufficiency and deficiency. Conclusions: Despite the common nutrition recommendations, there are differences between the Nordic countries in the implementation of the recommendations and policies to achieve adequate vitamin D intake and status. There is a need for wider Nordic collaboration studies as well as strategies to improve vitamin D status, especially in risk groups.

Effect of vitamin D fortified foods on bone markers and muscle strength in women of Pakistani and Danish origin living in Denmark: a randomised controlled trial

BACKGROUND

Deficient and insufficient vitamin D status (defined as serum 25(OH)D < 30 nmol/L and > 50 nmol/L) is prevalent worldwide and associated with decreased muscle strength and poor bone health. We aimed to investigate the effect of vitamin D fortification on bone markers and muscle strength among younger adult women at risk of vitamin D deficiency.

METHODS

A 12-week randomised double-blinded placebo-controlled winter intervention trial, providing 30 μg vitamin D₃/day through fortified yoghurt, cheese, eggs and crisp-bread or similar placebo products. Participants were 143 women of Danish and Pakistani origin 18-50 years of age, living in Denmark, randomised into four groups stratified by ethnicity. Serum 25-hydroxyvitamin D (25(OH)D) by LC-MS/MS and the secondary endpoints: four specific bone markers (osteocalcin (OC), Bone specific Alkaline Phosphatase (BALP), Procollagen type 1 amino-terminal propeptide (P1NP), C-terminal crosslinked telopeptide of type 1 collagen (CTX)) and three muscle strength measures (handgrip, knee extension strength, chair-standing), were assessed using one-way ANOVA, Tukey HSD and subsequent linear ANCOVA models, adjusted for relevant covariates.

RESULTS

Significantly increased serum 25(OH)D concentration from 53.3 (17) to 77.8 (14) nmol/L and from 44.5 (21) to 54.7 (18) nmol/L among Danish and Pakistani women in the fortified groups, respectively (P <  0.05). The bone turnover markers OC, BALP, P1NP and CTX did not change significantly. Muscle strength by handgrip, knee extension and chair-standing test did not change significantly following the intervention.

CONCLUSIONS

Consumption of vitamin D fortified foods for 12 weeks did not result in significant changes of the bone turnover markers OC, BALP, P1NP and CTX. Muscle strength measured as hand grip strength, knee extension strength and chair-standing did not change significantly following the intervention.

Effect of vitamin D supplementation on total and free 25 hydroxyvitamin D and parathyroid hormone. An analysis of two randomized controlled trials

BACKGROUND

It is questionable as to whether total serum 25 hydroxyvitamin D (T25D) levels are lower in African Americans. We measured serum T25D, free 25hydroxyvitamin D (F25D) and serum parathyroid hormone (PTH) in African American and Caucasian women and studied the effect of vitamin D dosing to determine if differences by race or age occur.

METHODS

Healthy young and older Caucasian and African American women who were vitamin D insufficient were randomized in two clinical trials to escalating daily doses of vitamin D from 400 to 4800 IU and placebo for 12 months.

RESULTS

Baseline F25D and T25D were significantly lower in young but not older African American compared to Caucasian women. At baseline, the rate of change, or slope, in F25D with T25D was significantly greater in younger women than in older women, but difference in the rate of change in F25D with T25D is similar in African American and Caucasian women. After vitamin D supplementation, there was an increase in F25D, and the dose response was not significantly different by age or race. The ratio of F25D/T25D decreased in all groups once T25D exceeded ~60 nmol L^-1 . There was a progressive decrease in serum PTH with increasing vitamin D doses and the per cent change was similar for F25D and T25D.

CONCLUSION

Serum F25D and T25D are lower in younger African American women, and since dietary vitamin D is similar in the groups, it is likely that the cause of low serum 25OHD in African American women is due to reduced UV exposure and reduced skin production of vitamin D.

Vitamin D status in preschool children and its relations to vitamin D sources and body mass index-Fish Intervention Studies-KIDS (FINS-KIDS)

OBJECTIVES

The aims of this study were to determine vitamin D status (serum 25-hydroxyvitamin D₃ [s-25(OH)D₃]) and examine possible associations between vitamin D status and vitamin D-rich dietary sources, sun exposure, and body mass index in preschool children ages 4 to 6 y.

METHODS

This is a cross-sectional study based on baseline data (collected in January-February 2015) from the two-armed randomized controlled trial Fish Intervention Studies-KIDS (FINS-KIDS) conducted in Bergen, Norway. S-25(OH)D₃ concentration was determined by liquid chromatography-tandem mass spectrometry. Information regarding habitual dietary intake, recent sun vacations, and body mass index were assessed with questionnaires answered by the children's caregivers.

RESULTS

The children (n = 212) had a mean (standard deviation) s-25(OH)D₃ of 60.7 (13.8) nmol/L; 18.9% had s-25(OH)D₃ ≤50 nmol/L. In logistic regression models, non-overweight versus overweight status was inversely associated with s-25(OH)D₃ ≤50 nmol/L (odds ratio: 0.41; 95% confidence interval, 0.18-0.95; P = 0.037). Non-sun versus sun vacations were associated with s-25(OH)D₃ ≤75 nmol/L (odds ratio: 5.33; 95% confidence interval, 1.93-14.77; P = 0.001).

CONCLUSIONS

The majority of the preschool children (81%) had s-25(OH)D₃ >50 nmol/L. Children with overweight status had an increased risk of s-25(OH)D₃ ≤50 nmol/L, and children who had not been on sun vacations were at a greater risk of s-25(OH)D₃ ≤75 nmol/L.

Vitamin D for secondary prevention of acute wheeze attacks in preschool and school-age children

INTRODUCTION

Vitamin D is best known for its role in bone health; however, the discovery of the vitamin D receptor and the expression of the gene encoding the vitamin D 1α-hydroxylase (CYP27B1) enzyme in a wide variety of tissues including immune cells and respiratory epithelium has led to the discovery of potential roles for vitamin D in the prevention of acute wheeze.

METHODS

We review here the literature concerning the relationships between circulating 25-hydroxyvitamin D (25(OH)D) concentration and secondary prevention of acute wheeze attacks in preschool and school-age children.

RESULTS

Epidemiological data suggest that vitamin D insufficiency (25(OH)D <75 nmol/L) is highly prevalent in preschool and school-age children with wheeze. Preschool age children with a history of wheeze attacks and circulating 25(OH)D <75 nmol/L are at increased risk and frequency of future acute wheeze. However, no consistent association between low vitamin D status and risk of acute wheeze is reported in school-age children. Seven randomised controlled trials (RCTs) with relatively small sample sizes (30-430) and variable quality showed inconsistent results regarding the effect of oral vitamin D supplementation during childhood on the risk of asthma attacks, asthma symptom control, inhaled corticosteroid requirements, spirometry and unscheduled healthcare attendances for wheeze. A RCT showed that vitamin D supplementation had no effect on the frequency of unplanned healthcare attendances due to acute wheeze in 22 preschool children.

DISCUSSION

An evidence-based recommendation for the use of vitamin D as a preventive therapy for wheeze attacks cannot be made until results of further trials are available. The assessment of circulating 25(OH)D concentration and the optimisation of vitamin D status to prevent acute respiratory tract infections, and to maintain skeletal and general health in preschool and school-age children with acute wheeze is worthwhile in its own right, but whether this will reduce the risk of acute wheeze attacks is unclear.