Supplement fads come and go and the most recent one to take the U.S. by storm has been to list vitamin D as both cause and cure of just about everything - and make some money selling vitamin supplements. It takes a while for science to catch up to spurious correlations and a recent study of elderly men found no evidence that obstructive sleep apnea increased in severity (or prevalence) as a result of vitamin D deficiency, despite what Joe Mercola or other health frauds are claiming this week.

The researchers also found no evidence to support a link between vitamin D deficiency and increased risk of OSA in non-obese study participants.

The researchers noted that the cohort of 2,827 participants whose data were analyzed in this study were generally healthy, mostly Caucasian (92.2%), elderly males (average age 76.4 years), therefore limiting the generalizability of the study results to other populations.

"The link between obesity and vitamin D deficiency can be explained a number ways, one of which is that obese individuals are less likely to be physically active, thereby limiting their sun exposure," said senior investigator Ken Kunisaki, MD, MS, Medical Director of the Sleep Apnea Program at the Minneapolis VA and Associate Professor of Medicine at the University of Minnesota. "Although our study was not designed to figure out why obese people have lower vitamin D levels, our results ultimately suggest that low vitamin D levels do not cause or worsen OSA. Therefore, taking additional vitamin D supplements is not likely to prevent or improve OSA."