There is little evidence that vitamin D can help with health conditions other than bone fractures, and people may be given doses unnecessarily, two West Australian researchers say.
Royal Perth Hospital consultant pathologist and endocrinologist Paul Glendenning and University of Western Australia academic Gerard Chew’s review of evidence from recent years found further studies were needed to establish any link between vitamin D deficiency and cancer risk, diabetes and infections.
“Unfortunately there’s not been many randomised clinical trials which is the highest level of evidence that we need before we start to advise individuals they should be taking supplementation to prevent those sort of diseases,” Dr Glendenning said.
He said it was possible people were being unnecessarily tested and treated for low vitamin D levels.
“We need to be identifying those individuals that are going to be benefit from testing, and when we’ve tested those individuals, if their vitamin level is low, treat them,” he said.
While there are many studies exploring the link between extraskeletal diseases and vitamin D absorption, there is a risk of “reverse causation” skewing results and more research is needed, the study found.
“Illness can result in the contraction of outdoor activities, reduced sunlight exposure and, accordingly, low 25(OH)D concentration may be a consequence, rather than a cause, of disease,” the paper said.
However Dr Glendenning said their work, published in the Medical Journal of Australia, did find some clear benefits of the vitamin.
“There’s a pretty much consistent message that calcium with vitamin D reduces fractures and has effects on fall rates,” he said.
In their article, Dr Chew and Dr Glendenning said frail, older patients with the highest likelihood of injury during a fall were most likely to benefit from supplements.
“There are specific sub groups within the population that are well worthwhile testing, but at the moment, we’re awaiting more data before we adopt a routine population-wide type screening program,” Dr Glendenning said.
Doctors ‘overwhelmed’ with information
The article states more than 2,000 peer-reviewed articles have been published on the topics of vitamin D testing, deficiencies and benefits within the past 12 months.
“One of the problems for an average practitioner in Australia is they’re overwhelmed with information,” Dr Glendenning said.
“If you can provide that information in a summarised format that they find easily accessible and easily digestible, then I think that’s part of the issue.”
The pair have recommended education initiatives to raise awareness of the current guidelines for vitamin D testing and supplements, as well auditing local practices.