Faculty Bibliography

BACKGROUND:A 2021 meta-analysis of 37 randomised controlled trials (RCTs) of vitamin D supplementation for prevention of acute respiratory infections (ARIs) revealed a statistically significant protective effect of the intervention (odds ratio [OR] 0·92 [95% CI 0·86 to 0·99]). Since then, six eligible RCTs have been completed, including one large trial (n=15 804). We aimed to re-examine the link between vitamin D supplementation and prevention of ARIs. METHODS:Updated systematic review and meta-analysis of data from RCTs of vitamin D for ARI prevention using a random effects model. Subgroup analyses were done to determine whether effects of vitamin D on risk of ARI varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration, dosing regimen, or age. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science, and the ClinicalTrials.gov between May 1, 2020 (end-date of search of our previous meta-analysis) and April 30, 2024. No language restrictions were imposed. Double-blind RCTs supplementing vitamin D for any duration, with placebo or lower-dose vitamin D control, were eligible if approved by a Research Ethics Committee and if ARI incidence was collected prospectively and pre-specified as an efficacy outcome. Aggregate data, stratified by baseline 25(OH)D concentration and age, were obtained from study authors. The study was registered with PROSPERO (no. CRD42024527191). FINDINGS/RESULTS:=0·0%). A funnel plot showed left-sided asymmetry (p=0·0020, Egger's test). INTERPRETATION/CONCLUSIONS:This updated meta-analysis yielded a similar point estimate for the overall effect of vitamin D supplementation on ARI risk to that obtained previously, but the 95% CI for this effect estimate now includes 1·00, indicating no statistically significant protection. FUNDING/BACKGROUND:None.

There is controversy over whether African Americans have higher vitamin D requirements than recommended by the Institute of Medicine. We previously reported that maintaining serum 25(OH)D above 30 ng/mL does not prevent age-related bone loss. Herein, we report that bone strength is also unaffected by maintaining this level in this population.

Abdominal aortic calcification (AAC) detected on lateral vertebral fracture assessment is associated with increased cardiovascular risk. Vitamin D deficiency and toxicity have been linked with vascular calcification. The objective of this study was to determine the effect of high-dose vitamin D on the progression of AAC. The Physical Performance, Osteoporosis and vitamin D in African American Women (PODA) is a randomized, clinical trial examining the effect of vitamin D. There were 14.7% subjects with AAC in the vitamin D group, compared to 12.1% in the placebo group at baseline. The prevalence of extended AAC at baseline was 6.4% in the vitamin D group and 3.5% in the placebo group. The extended calcification scores over time were not different between groups. There was no association between AAC and serum 25(OH)D. However, PTH was associated with an increase in AAC in the placebo group.

The following corrections are found in the original publication of the article and corrected as below.

Background/UNASSIGNED:There is considerable heterogeneity in clinical trials examining the role of vitamin D in the prevention of acute respiratory infections (ARIs). Methods/UNASSIGNED:The primary aim of the Physical Performance, Osteoporosis, and Vitamin D in Older African-American Women (PODA) trial was the prevention of bone loss and decline in physical performance. A questionnaire about ARIs was administered every 3 months for 3 years to 260 black American women in a double-blind randomized clinical trial that had a placebo group and a vitamin D supplementation group. The serum 25(OH)D level was maintained >30 ng/mL in the vitamin D group. Results/UNASSIGNED:Serum 25(OH)D was maintained >30 ng/mL in 90% of the active group, whereas levels approximated those associated with the recommended dietary allowance (20 ng/mL) in the placebo group. There was no difference in occurrence of ARIs in the treatment group vs the placebo group. ARIs were not related to total or free 25(OH)D, which were measured at baseline and annually for 36 months. Conclusions/UNASSIGNED:Vitamin D supplementation sufficient to maintain serum 25(OH)D >30 ng/mL does not prevent ARIs in older African American women. ClinicalTrialsgov Registration Number/UNASSIGNED:NCT01153568.

Context/UNASSIGNED:There is limited information on the influence of vitamin D on physical performance in black Americans. Objective/UNASSIGNED:To determine if maintenance of serum 25(OH)D above 75 nmol/L prevents the decline in physical performance. Design/UNASSIGNED:The PODA trial had a prospective, randomized, placebo controlled, double-dummy design with two arms: one with placebo vitamin D3 adjusted to maintain serum 25(OH)D above 75 nmol/L. Patients/UNASSIGNED:The target population was healthy elderly black women with serum 25(OH)D between 20 and 65 nmol/L. The trial was 3 years in duration with measurement of physical performance every 6-months: Grip strength, Short Physical Performance Battery (SPPB), 10 chair rises and 6-minute walk distance. 260 women entered the study and 184 completed 3 years. Mean age was 68.2 years. Baseline 25(OH)D was 53 nmol/L and total SPPB was 11 (10-12). Setting/UNASSIGNED:Research Center in an Academic Health Center. Main Outcomes Measure/UNASSIGNED:Prevention of decline in physical performance measures. Intervention/UNASSIGNED:Participants were randomly assigned to placebo or active vitamin D. Vitamin D3 dose was adjusted to maintain serum 25(OH)D above 75 nmol/l. Results/UNASSIGNED:There was a decline with time in grip strength and the 6-minute walk. The SPBB increased with time. There were no significant differences between the placebo and active vitamin D3 groups with respect to the temporal patterns observed for any of the performance measures. Conclusions/UNASSIGNED:There is no benefit of maintaining serum 25(OH)D above 75 nmol/L in preventing the decline in physical performance in healthy black American women.

BACKGROUND:Limited information is available on the influence of vitamin D on falls in older high-functioning black American women. Endocrine Society guidelines propose serum 25(OH)D levels over 30 ng/mL. OBJECTIVE:To determine if maintenance of serum 25(OH)D above 30 ng/mL protects against falls. DESIGN/METHODS:adjusted to maintain serum 25(OH)D above 30 ng/mL. The primary outcomes were the prevention of bone loss and the decline in physical performance. PATIENTS/METHODS:The target population was healthy black women older than 60 years with serum 25(OH)D between 8 and 26 ng/mL. The trial was 3 years in duration with a falls questionnaire administered every 3 months. A total of 260 women entered the study, and 184 completed the 3 years. Mean age was 68.2 years. SETTING/METHODS:Research center in an academic health center. MAIN OUTCOMES MEASURE/METHODS:Prevention of falls. INTERVENTION/METHODS:dose was adjusted to maintain serum 25(OH)D above 30 ng/mL in the active group using a double-dummy design. RESULTS:Baseline 25(OH)D was 22 ng/mL. Mean serum 25(OH)D reached 47 ng/mL in the active group compared with 21 ng/mL in the placebo group. There were 14.2% falls in the previous year recalled at baseline. During the study, 46% reported falling in the treatment group compared with 47% in the placebo group. There was no association of serum 25(OH)D or vitamin D dose with the risk of falling. CONCLUSIONS:There is no benefit of maintaining serum 25(OH)D above 30 ng/mL compared with the Institute of Medicine recommendation (20 ng/mL) in preventing falls in healthy older black American women.

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/OBJECTIVE: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/METHODS: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/METHODS:of any duration having incidence of acute respiratory infection as a prespecified efficacy outcome were selected. STUDY APPRAISAL/UNASSIGNED: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: = 0.83). The body of evidence contributing to these analyses was assessed as being of high quality. LIMITATIONS/CONCLUSIONS: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/BACKGROUND:This study is registered as PROSPERO CRD42014013953. FUNDING/BACKGROUND:The National Institute for Health Research Health Technology Assessment programme.