A new analysis of a randomized controlled trial has found that vitamin D helps inspiratory muscle strength and peak exercise tolerance in chronic obstructive pulmonary disease (COPD) patients.
The study, published in the journal Respiratory Research and led by Dr Miek Hornikx and colleagues of the University Hospital Gasthuisberg in Belgium, studied a subgroup of patients that were administered 100,000 IU of vitamin D per month for a year and participated in a three month rehabilitation program at the beginning of the study.
COPD is considered a complex disease and is marked by the occurrence of chronic bronchitis or emphysema. It is defined by low airflow in the lung and gets worse over time. Smoking is the primary cause, but there are other causes, too, like air pollution and exposure to coal dust. Comorbidities include skeletal muscle weakness, which is why patients with COPD are often suggested to enroll in a rehabilitation program.
In this study, this subgroup was part of a larger study that sought to discover if vitamin D could help reduce exacerbations. While the larger study had 182 enrollees, only 50 of these enrollees participated in this three month training program. The participants were split evenly to either receive 100,000 IU of vitamin D/month or placebo. These patients had to complete 90 minutes of training three times per week, consisting of a circuit of exercises including: cycling, walking on the treadmill, stair climbing, and strength exercises for the upper and lower extremities and arm cranking.
The researchers wanted to see if vitamin D enhanced the effects of rehabilitation training via pulmonary function, peripheral muscle strength, respiratory muscle strength, functional exercise capacity, maximal exercise capacity, and health-related quality of life.
After three months of training, the researchers noted the following changes:
- Vitamin D levels increased from 15 to 51 ng/ml in the vitamin D group and remained stable in the placebo group, from 19 ng/ml to 18 ng/ml.
- Inspiratory muscle strength significantly improved more in the vitamin D group compared to placebo.
- Maximal oxygen uptake significantly improved in the vitamin D group compared to placebo, thus improving peak exercise tolerance.
- Though not statistically significant, there was a trend toward higher quadriceps strength, six minutes walking distance and dyspnea scores in the vitamin D group compared to placebo.
The authors note that their subject numbers and small length of study may not have produced the most statistically and clinically significant findings, but this small set of data is encouraging for future study and practice. They state:
“Overall, the present post-hoc analysis supports the idea that in patients with COPD high dose supplementation with vitamin D can be beneficial when combined with exercise training.”
Here, the investigators raised levels to 50 ng/ml on a dose equivalent to 3,300 IU of vitamin D/day and found some encouraging results for COPD patients. The Vitamin D Council recommends 5,000 IU/day for the general population.