Association between vitamin D status and asthma control: A meta-analysis of randomized trials

Abstract

Background: There is a controversy in terms of the efficacy of vitamin D supplementation in improving asthma symptom control. Moreover, whether there is a difference in the treatment effect with respect to baseline vitamin D status remains unknown. This meta-analysis was to assess the correlations of vitamin D status with asthmarelated respiratory outcomes. Methods: PubMed, EMBASE, and Cochrane Library were searched for randomized controlled trials of vitamin D supplementation in patients with asthma. Primary outcomes were the rate of asthma exacerbation and predicted percentage of forced expiratory volume in first second (FEV 1 %). Secondary outcomes were asthma control test (ACT) scores, fractional exhaled nitric oxide (FeNO), interleukin-10 (IL-10) and adverse events. Results: A total of 14 randomized controlled trials (1421 participants) fulfilled the inclusion. Vitamin D supplementation was associated with a significant reduction in the rate of asthma exacerbation by 27% (RR: 0.73 95%Cl (0.58-0.92)). In subgroup analysis, the protective effect of exacerbation was restricted in patients with vitamin D insufficiency (vitamin D < 30 ng/ml) (RR: 0.76 95%Cl (0.61-0.95)). An improvement of FEV 1 % was demonstrated in patients with vitamin D insufficiency and air limitation (FEV 1 % < 80%) (MD: 8.3 95%Cl (5.95-10.64). No significant difference was observed in ACT scores, FeNO, IL-10 and adverse events. Conclusions: Vitamin D supplementation reduced the rate of asthma exacerbation, especially in patients with vitamin D insufficiency. Additionally, the benefit of vitamin D had a positive effect on pulmonary function in patients with air limitation and vitamin D insufficiency.

Targeting Vitamin D Deficiency to Limit Exacerbations in Respiratory Diseases: Utopia or Strategy With Potential?

“…Indeed, many RCTs of vitamin D supplementation to improve asthma control and exacerbations have been completed and these studies have reported a mixture of positive and negative results. However, several meta-analyses show that vitamin D supplementation significantly reduced the rate of severe exacerbations in patients with asthma [109][110][111][112][113]. Whether these effects are only observed in patients with vitamin D deficiency, as was shown in COPD, is less clear since only two studies performed subgroups analysis, showing conflicting results [112,113].…”

“…However, several meta-analyses show that vitamin D supplementation significantly reduced the rate of severe exacerbations in patients with asthma [109][110][111][112][113]. Whether these effects are only observed in patients with vitamin D deficiency, as was shown in COPD, is less clear since only two studies performed subgroups analysis, showing conflicting results [112,113]. While the most recent meta-analysis clearly concluded that vitamin D supplementation played a role in reducing the rate of exacerbations particularly in patients with vitamin D insufficiency [113], subgroup analysis using individual patient data did not result in such a firm conclusion [112].…”

“…Whether these effects are only observed in patients with vitamin D deficiency, as was shown in COPD, is less clear since only two studies performed subgroups analysis, showing conflicting results [112,113]. While the most recent meta-analysis clearly concluded that vitamin D supplementation played a role in reducing the rate of exacerbations particularly in patients with vitamin D insufficiency [113], subgroup analysis using individual patient data did not result in such a firm conclusion [112]. Indeed, reductions in exacerbation rate were found with vitamin D supplementations but only in participants with baseline circulating 25(OH)D levels less than 25 nmol/l and not in those with higher levels of circulating 25(OH)D (adjusted incidence rate ratio was 0.33 (95% CI 0.11-0.98) and 0.77 (95% CI 0.58-1.03), respectively).…”

Severity of Asthma and Serum Vitamin D Levels in Asthmatic Children

“…Studies showed that children who have taken supplementary vitamin D during the first year of life have a lower risk of asthma at 31 years of age, but there was no report of vitamin D levels during this period [29]. A meta-analysis of randomized trials show the rate of asthma exacerbation can reduce by vitamin D supplementation especially in patients with vitamin D insufficiency [30]. Litonjua (2019) suggested vitamin D supplementation can prevent asthma and wheeze in early life, and may help in treatment of asthma [31].…”

Salmon Intake Intervention in the Vulnerable Group of Young Polish Women to Maintain Vitamin D Status during the Autumn Season

“…Recent meta-analyses show that vitamin D deficiency is associated with a higher risk of sleep disorders [2] and may be related to autoimmune thyroid disease [3], whereas high vitamin D serum levels have a protective effect on breast cancer in premenopausal women [4]. They also indicate that vitamin D supplementation significantly reduces cancer mortality [5], as well as the rate of asthma exacerbations [6]. Taking it into account, scientists agree that vitamin D goes beyond influencing bone health only [7,8].…”