"Our research shows that vitamin D may have a strong influence on lunghealth, with greater levels of vitamin D associated with greater and morepositive effects on lung function," said lead author Peter Black from theUniversity of Auckland.
The relationship between lung function and vitamin D was examined by using14,000 participants from the US National Health and Nutrition ExaminationSurvey (NHANES III) carried out between 1988 and 1994.
Lung function was measured by the volume of air that could be forcibly blownout in total, the forced vital capacity (FVC), or in one second, the forcedexpiratory volume (FEV1). Vitamin D was quantified by serum25-hydroxyvitamin D, the standard indicator of vitamin D levels.
"The difference in lung function between the highest and lowest [levels] ofvitamin D is substantial [106 mL for FEV1, and 142 mL for FVC]," said Dr Black.
"Although there is a definite relationship between lung function and vitaminD, it is unclear if increases in vitamin D through supplements or dietaryintake will actually improve lung function in patients with chronicrespiratory diseases," he said.
An earlier study from Harvard University also proposed a link betweenvitamin D and lung health. Presented at the 96th Annual Meeting of theAmerican Association for Cancer Research (April 2005) this researchsuggested that high levels of vitamin D from diets, supplements and sunlight exposure enhanced the survival rates of patients recovering from lung-cancer surgery.
The researchers from New Zealand said that vitamin D supplements could be asimple, low-cost method to prevent or slow the loss of lung function. Theystressed, however, that further studies were needed to establish the exactrelationship between vitamin D and lung function.
Vitamin D supplements have been recommended to specific demographic groupsin countries like Denmark and Britain due to its positive link to bonehealth. A recent study from Iceland suggested that vitamin D levels weremore important than calcium to ensure healthy bones. The Europeanrecommended daily allowance of vitamin D is 5 micrograms per day.
The research was published in the December issue of Chest (vol 128, no 6).