Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials.

BACKGROUND: A 2017 meta-analysis of data from 25 randomised controlled trials (RCTs) of vitamin D supplementation for the prevention of acute respiratory infections (ARIs) revealed a protective effect of this intervention. We aimed to examine the link between vitamin D supplementation and prevention of ARIs in an updated meta-analysis. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, and the ClinicalTrials.gov registry for studies listed from database inception to May 1, 2020. Double-blind RCTs of vitamin D3, vitamin D2, or 25-hydroxyvitamin D (25[OH]D) supplementation for any duration, with a placebo or low-dose vitamin D control, were eligible if they had been approved by a research ethics committee, and if ARI incidence was collected prospectively and prespecified as an efficacy outcome. Studies reporting results of long-term follow-up of primary RCTs were excluded. Aggregated study-level data, stratified by baseline 25(OH)D concentration and age, were obtained from study authors. Using the proportion of participants in each trial who had one or more ARIs, we did a random-effects meta-analysis to obtain pooled odds ratios (ORs) and 95% CIs to estimate the effect of vitamin D supplementation on the risk of having one or more ARIs (primary outcome) compared with placebo. Subgroup analyses were done to estimate whether the effects of vitamin D supplementation on the risk of ARI varied according to baseline 25(OH)D concentration (<25 nmol/L vs 25·0-49·9 nmol/L vs 50·0-74·9 nmol/L vs >75·0 nmol/L), vitamin D dose (daily equivalent of <400 international units [IU] vs 400-1000 IU vs 1001-2000 IU vs >2000 IU), dosing frequency (daily vs weekly vs once per month to once every 3 months), trial duration (≤12 months vs >12 months), age at enrolment (<1·00 years vs 1·00-15·99 years vs 16·00-64·99 years vs ≥65·00 years), and presence versus absence of airway disease (ie, asthma only, COPD only, or unrestricted). Risk of bias was assessed with the Cochrane Collaboration Risk of Bias Tool. The study was registered with PROSPERO, CRD42020190633. FINDINGS: We identified 1528 articles, of which 46 RCTs (75 541 participants) were eligible. Data for the primary outcome were obtained for 48 488 (98·1%) of 49 419 participants (aged 0-95 years) in 43 studies. A significantly lower proportion of participants in the vitamin D supplementation group had one or more ARIs (14 332 [61·3%] of 23 364 participants) than in the placebo group (14 217 [62·3%] of 22 802 participants), with an OR of 0·92 (95% CI 0·86-0·99; 37 studies; I2=35·6%, pheterogeneity=0·018). No significant effect of vitamin D supplementation on the risk of having one or more ARIs was observed for any of the subgroups defined by baseline 25(OH)D concentration. However, protective effects of supplementation were observed in trials in which vitamin D was given in a daily dosing regimen (OR 0·78 [95% CI 0·65-0·94]; 19 studies; I2=53·5%, pheterogeneity=0·003), at daily dose equivalents of 400-1000 IU (0·70 [0·55-0·89]; ten studies; I2=31·2%, pheterogeneity=0·16), for a duration of 12 months or less (0·82 [0·72-0·93]; 29 studies; I2=38·1%, pheterogeneity=0·021), and to participants aged 1·00-15·99 years at enrolment (0·71 [0·57-0·90]; 15 studies; I2=46·0%, pheterogeneity=0·027). No significant interaction between allocation to the vitamin D supplementation group versus the placebo group and dose, dose frequency, study duration, or age was observed. In addition, no significant difference in the proportion of participants who had at least one serious adverse event in the vitamin supplementation group compared with the placebo group was observed (0·97 [0·86-1·07]; 36 studies; I2=0·0%, pheterogeneity=0·99). Risk of bias within individual studies was assessed as being low for all but three trials. INTERPRETATION: Despite evidence of significant heterogeneity across trials, vitamin D supplementation was safe and overall reduced the risk of ARI compared with placebo, although the risk reduction was small. Protection was associated with administration of daily doses of 400-1000 IU for up to 12 months, and age at enrolment of 1·00-15·99 years. The relevance of these findings to COVID-19 is not known and requires further investigation. FUNDING: None.

Suboptimal feeding and caring practices among young Indian children ages 12 to 24 mo living in the slums of New Delhi.

OBJECTIVES: Inappropriate infant and young child feeding and caring practices affect nutritional status, increases the risk for growth faltering, and ultimately, affect child survival. The aim of this study was to characterize the feeding and caring practices of disadvantaged urban Indian children 12 to 24 mo of age in relation to the World Health Organization (WHO) and Pan American Health Organization (PAHO) recommendations. METHODS: This cross-sectional study was conducted in self-selected households in a South Delhi slum. A household survey was administered to the mother/primary caregiver of 120 eligible children. We collected child anthropometry, 2-d weighed food records (n = 69), and compliance to WHO and PAHO recommended feeding, caring, food safety, and hygiene practices. RESULTS: Of the children, 39% were stunted, 31% underweight, and 10% wasted; none were overweight. Despite 88% achieving minimum meal frequency (more than three to four meals daily), only 50% consumed at least four food groups (minimum dietary diversity), and 44% a minimum acceptable diet (composite score of minimum meal frequency and minimum dietary diversity). Consumption of iron-rich or iron-fortified foods, vitamin A-rich fruits and vegetables, and eggs was low (<25%) and flesh foods were negligible (1.4%), whereas consumption of both sugary and snack foods was >60%. Reported compliance to responsive feeding indicators was generally ∼50%, but there was a wide range (13-98%) for food safety and hygiene practices, which were not always consistent with home observations. CONCLUSIONS: Complementary feeding and caregiving practices were suboptimal among these disadvantaged young Indian children and education interventions focused on infant and young child feeding, responsive feeding, food safety, and hygiene practices are urgently needed.

Vitamin D supplementation to prevent acute respiratory infections: individual participant data meta-analysis.

BACKGROUND: Randomised controlled trials (RCTs) exploring the potential of vitamin D to prevent acute respiratory infections have yielded mixed results. Individual participant data (IPD) meta-analysis has the potential to identify factors that may explain this heterogeneity. OBJECTIVES: To assess the overall effect of vitamin D supplementation on the risk of acute respiratory infections (ARIs) and to identify factors modifying this effect. DATA SOURCES: MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, ClinicalTrials.gov and the International Standard Randomised Controlled Trials Number (ISRCTN) registry. STUDY SELECTION: Randomised, double-blind, placebo-controlled trials of supplementation with vitamin D3 or vitamin D2 of any duration having incidence of acute respiratory infection as a prespecified efficacy outcome were selected. STUDY APPRAISAL: Study quality was assessed using the Cochrane Collaboration Risk of Bias tool to assess sequence generation, allocation concealment, blinding of participants, personnel and outcome assessors, completeness of outcome data, evidence of selective outcome reporting and other potential threats to validity. RESULTS: We identified 25 eligible RCTs (a total of 11,321 participants, aged from 0 to 95 years). IPD were obtained for 10,933 out of 11,321 (96.6%) participants. Vitamin D supplementation reduced the risk of ARI among all participants [adjusted odds ratio (aOR) 0.88, 95% confidence interval (CI) 0.81 to 0.96; heterogeneity p < 0.001]. Subgroup analysis revealed that protective effects were seen in individuals receiving daily or weekly vitamin D without additional bolus doses (aOR 0.81, 95% CI 0.72 to 0.91), but not in those receiving one or more bolus doses (aOR 0.97, 95% CI 0.86 to 1.10; p = 0.05). Among those receiving daily or weekly vitamin D, protective effects of vitamin D were stronger in individuals with a baseline 25-hydroxyvitamin D [25(OH)D] concentration of < 25 nmol/l (aOR 0.30, 95% CI 0.17 to 0.53) than in those with a baseline 25(OH)D concentration of ≥ 25 nmol/l (aOR 0.75, 95% CI 0.60 to 0.95; p = 0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (aOR 0.98, 95% CI 0.80 to 1.20; p = 0.83). The body of evidence contributing to these analyses was assessed as being of high quality. LIMITATIONS: Our study had limited power to detect the effects of vitamin D supplementation on the risk of upper versus lower respiratory infection, analysed separately. CONCLUSIONS: Vitamin D supplementation was safe, and it protected against ARIs overall. Very deficient individuals and those not receiving bolus doses experienced the benefit. Incorporation of additional IPD from ongoing trials in the field has the potential to increase statistical power for analyses of secondary outcomes. STUDY REGISTRATION: This study is registered as PROSPERO CRD42014013953. FUNDING: The National Institute for Health Research Health Technology Assessment programme.

Effects of vitamin D supplementation in infancy on growth, bone parameters, body composition and gross motor development at age 3-6 years: follow-up of a randomized controlled trial.

BACKGROUND: The long-term effects of infant vitamin D supplementation and status are unclear since there have been few controlled intervention trials and these have been small and contradictory. The Delhi Infant Vitamin D Supplementation (DIVIDS) trial found that supplementation of low-birthweight term infants with one recommended dietary allowance of vitamin D from 1 week to 6 months of age resulted in increased length and weight at 6 months. In the DIVIDS-2 study we followed up the DIVIDS children, now aged 3-6 years, to determine longer-term effects. METHODS: DIVIDS children, 446 from the vitamin D arm and 466 from the placebo arm, attended the follow-up visit. Data collection included anthropometry, blood pressure, bone structure and strength by quantitative ultrasound (QUS), gross motor tests, deuterium dilution test of body composition on a subset (n = 229) and blood samples for measurement of vitamin D status. RESULTS: Body mass index Z scores (BMIZ) were lower (adjusted P = 0.003)in the vitamin D Group [-1.18 (SD 0.92)] when compared with the placebo [-1.02 (SD 0.91)] group as a result of slightly lower weight and slightly greater height. The vitamin D group also had lower thigh circumference and arm muscle area and borderline lower mid-upper arm circumference. There were no group differences in body fat percentage, bone QUS or blood pressure and few differences in motor development measures. CONCLUSIONS: Vitamin D supplementation of low-birthweight infants in infancy resulted in children being thinner at age 3-6 years but in no differences in functional outcomes.