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Vitamin D3 supplementation improved exercise tolerance in deficient male COPD patients in small RCTVitamin D supplements linked to better walking ability in men with COPD and low vitamin D

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Key Takeaway
Consider vitamin D3 status in deficient COPD patients, but note evidence for supplementation is preliminary.

This 26-week, double-blind, randomized controlled trial enrolled 40 male smokers aged 40-80 years with stable COPD (post-bronchodilator FEV1/FVC <0.70) and vitamin D3 deficiency (serum 25(OH)D <30 ng/ml). The intervention group received oral vitamin D3 capsules: 80,000 IU/week for 13 weeks, followed by 40,000 IU per one to six weeks for another 13 weeks, adjusted according to serum 25(OH)D and calcium levels. The control group received placebo capsules. Both groups were advised daily sunlight exposure (5-15 minutes, 11am-4pm).

After 26 weeks, the vitamin D3 group showed statistically significant improvements compared to placebo in three secondary outcomes: 6-minute walk distance (p<0.05), dyspnea score (p<0.001), and fatigue score (p<0.001). The study did not report absolute numbers, effect sizes, or confidence intervals for these improvements. The primary outcome was not explicitly stated, and the study did not show improvement in ventilatory variables.

Safety and tolerability data were not reported. Key limitations include the small sample size (n=40), all-male population, and lack of reported effect sizes or absolute outcome numbers. All patients received sunlight exposure advice alongside the intervention or placebo, making it difficult to isolate the effect of supplementation alone. Funding sources and conflicts of interest were not reported.

For practice, this preliminary evidence suggests vitamin D3 supplementation may improve exercise tolerance and symptoms in vitamin D3-deficient male COPD patients, but the findings are limited by study size and design. Clinicians should interpret these results cautiously while awaiting larger, more comprehensive trials that include diverse patient populations and report complete outcome data.

Researchers studied whether vitamin D supplements could help men with chronic obstructive pulmonary disease (COPD) who also had low vitamin D levels. The study included 40 male smokers with stable COPD who were deficient in vitamin D. Half received high-dose vitamin D capsules for 26 weeks, while the other half received placebo capsules. All participants were also advised to get 5-15 minutes of daily sunlight exposure.

After six months, the men who took vitamin D showed statistically significant improvements in three areas compared to the placebo group. They could walk farther in a six-minute walking test, reported less breathlessness, and felt less fatigue. The study did not report any safety concerns or side effects from the vitamin D supplementation.

It's important to be cautious about these results for several reasons. This was a small study with only 40 participants, all of whom were men. The researchers did not report exactly how much improvement occurred or provide detailed numbers. Also, since everyone was told to get sunlight, it's unclear how much that advice contributed to the results. The study did not find improvements in actual lung function measurements.

This research suggests vitamin D supplementation might help with exercise tolerance and symptoms in a specific group of people with COPD. However, it's too early to make general recommendations. People with COPD should talk with their doctor before starting any new supplement, as individual needs and risks vary.

What this means for you:
Early, small study suggests vitamin D may help some men with COPD walk farther, but more research is needed.

Study Details

Study typeRct
Sample sizen = 20
EvidenceLevel 2
Follow-up960.0 mo
PublishedApr 2026
View Original Abstract ↓
Newer functional aspects of vitamin D₃ have been revealed in tissue and organs other than bones. In several studies, vitamin D₃ supplementation showed significant improvement in exercise tolerance in various co-morbid patients but precise connection is not clear, in Chronic Obstructive Pulmonary Disease (COPD) patients. This study aimed to evaluate the effects of vitamin D₃ supplementation on exercise tolerance in D₃ deficient patients with COPD. A double-blinded randomized controlled trial was carried out on 40 D₃ deficient [serum 25(OH)D <30 ng/ml], male, smoker (>4 pack years), stable COPD (post-bronchodilator FEV1/FVC <0.70) patients (age 40 to 80 years) and randomly allocated as study (n=20) and control (n=20). Their baseline exercise tolerance [6 minute walk distance (6MWD), dyspneic score, fatigue score] variables were measured. Then oral capsules of D₃ [80,000IU/week for 13 weeks, followed by 40,000 IU per one to six weeks for further 13 weeks, according to serum 25(OH)D and calcium] and placebo were provided to 'Study' and 'Control' patients, respectively, for consecutive 26 weeks. Additionally, all patients of both groups were also advised to have sunlight exposure (within 11am to 4pm) at least for 5 to15 minutes daily. On 26th week of follow-up, all the exercise tolerance variables were again measured. Results were expressed as mean±SD and percentage. The data were statistically analyzed by SPSS (Version 16.0), using independent sample 't'-test and paired Student's 't-test, where p≤0.05 level was accepted as significant. Statistically significant improvement was observed in 6MWD (p<0.05), dyspneic score (p<0.001) and fatigue score (p<0.001) in our D₃ supplemented patients than those with a placebo after 26 weeks of follow-up. This study reveals that Vitamin D₃ supplementation can improve exercise tolerance but not ventilatory variables in D₃ deficient stable patients of COPD.
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