A team of scientists from New Zealand have found that Vitamin D could play a role in keeping the lungs healthy.
The researchers from the University of Auckland found in a study of 14,091 people, that those with higher vitamin D levels in their blood had significantly better lung function.
They say the difference between the two was more marked than that between smokers and those who had quit.
The findings have led the team to suggest that dietary supplements could possibly boost lung function, but they add that more research is needed.
Dr Michael Alberts, president of the American College of Chest Physicians says that chronic lung conditions compromise the quality of life for millions of people around the world and by understanding the effect that vitamins have on lung function, it may be possible to identify new and more effective treatments for these debilitating diseases.
Lead researcher Dr Peter Black says that low levels of vitamin D have been associated with osteoporosis, hypertension, diabetes, and cancer. Now he says, their research shows that vitamin D may also have a strong influence on lung health, with greater levels of vitamin D being associated with greater and more positive effects on lung function.
Dr Black says the difference in performance between those with the highest and lowest concentrations of vitamin D was more marked that the difference between non-smokers and those who had given up.
The team found that those people with the highest concentration of vitamin D in their blood significantly outperformed others in tests to measure their lung function.
However, he also says that although there is a definite relationship between lung function and vitamin D, it is unclear if increases in vitamin D through supplements or dietary intake will actually improve lung function in patients with chronic respiratory diseases.
The FVC test was used which measures the total volume of air that is expelled after taking a deep breath.
The researchers found vitamin D was higher in men than women, was inversely related to obesity levels, and declined with age.
It was also lower in participants smoking more than 20 cigarettes a day compared with non-smokers.
Dr Peter Black said he is unsure why vitamin D has this effect on lung function, but suggests it may be because vitamin D affects the repair and remodelling of lung tissue, which goes on throughout life.
He believes the effects of vitamin D are not limited to bone and says there is evidence that it can affect the growth of a wide variety of cell types.
Dr Mark Britton, a spokesman for the British Lung Foundation, says that it is likely that vitamin D has an impact on the development of the rib cage, rather than the lung tissue itself and the failure to develop strong bones could impact on the size of the lungs.
Unlike other vitamins, it can be made in our bodies as a result of exposure to sunlight, providing the necessary starting materials are there to start with.
It is also contained in a few foods including oily fish, fish oils, butter and eggs.
The study is published in the journal Chest.
Revision date: July 5, 2011
Last revised: by Jorge P. Ribeiro, MD