A new study published by a research group in Korea reported a higher prevalence of vitamin D deficiency in people with chronic obstructive pulmonary disease (COPD). The amount of airflow problems and decreased ability to exercise corresponded with a lack of vitamin D.
In COPD the lungs are damaged, usually due to smoking, making it difficult for patients to breathe. In 2011, an estimated 12.7 million U.S. adults had COPD, although about 24 million U.S. adults had signs of impaired lung function, which means COPD may be under-diagnosed. It is the third most common cause of death in the U.S., claiming about 130,000 lives a year.
Different studies have focused on the relationship between vitamin D and COPD, but results so far have conflicted with one another.
The current study, titled “Relationship of vitamin D status with lung function and exercise capacity in COPD“ appeared in the April 13th issue of the journal Respirology. Led by Ji Ye Jung of Yonsei University College of Medicine, Seoul, Korea, the researchers studied 193 patients with COPD from the Korean Obstructive Lung Disease Cohort (the KOLD study). The overall purpose of the KOLD study is to develop new ways of assessing how COPD progresses based on biomarkers and other clinical measurements.
To unravel the relationship between vitamin D and COPD, the researchers measured vitamin D in the blood as well as lung function, 6-minute walking distance, quality of life, and the degree of emphysema.
The investigators categorized the study subjects into three groups, depending on the severity of the disease: normal 12 (6.2%), insufficiency 28 (14.5%) and deficiency 153 (79.3%). People with lower vitamin D levels had more trouble breathing. They also were unable to walk as far as people who had higher levels of vitamin D. Low vitamin D surprisingly was not associated with lower quality of life or an increased presence of emphysema.
In their report, the authors concluded, “We demonstrated a high prevalence of vitamin D deficiency in Korean patients with COPD and a significant relationship between vitamin D deficiency and airflow limitation. The exercise capacity tended to be decreased in the vitamin D deficiency group.”
The study could help identify predictors for breathing and exercise difficulties in people with COPD. In addition, it may indicate that vitamin D supplementation is important for people with COPD and for people with risk factors for developing COPD. However, the current study did not examine vitamin D supplementation. Further research into the relationship between nutritional factors and COPD will be valuable.