Vitamin D supplements provide little - if any - health benefits, a study shows.
The Auckland University report analysed multiple existing studies focused on the effects of vitamin D.
It found they failed to reduce the risk of heart attacks, strokes, cancer or bone fractures in the general population by more than 15 per cent.
Vitamin D supplements are commonly associated with better health and the prevention of various medical conditions. However, an emerging body of research is beginning to debunk these beliefs.
A study published last month in The Lancet Diabetes & Endocrinology journal concluded low levels of vitamin D were a result, rather than a cause, of ill-health.
The latest study, led by Dr Mark Bolland from the university's Department of Medicine, analysed comparisons of individuals who took calcium with their vitamin D supplements and those who didn't. Calcium is essential for healthy bones and teeth.
Some of Bolland's research indicates an increased risk of hip fractures with vitamin D supplementation.
It follows studies that showed vitamin D supplements made no difference in preventing osteoporosis in most healthy adults.
Arapera Salter took supplements two years ago when she had low vitamin D levels and she stands by the decision.
A prescription from her family doctor for three high-dose supplements, taken once a month, cost $5.
The 32-year-old paediatric registrar, who had her first child five weeks ago, wanted her vitamin D levels right before getting pregnant.
"I wanted to have good levels before I was pregnant because if you've got low vitamin D then your baby will get low vitamin D."
Salter said she intended to have her vitamin D levels retested once she stopped breastfeeding and, if needed, begin taking the supplements again.
"I definitely don't feel like I've wasted my money.
"Even though [the research] doesn't show that it prevents fractures, it's something that is down the line, like when you've got frail bones. I would rather try to prevent her [daughter Aniwa] from having that."
Salter lives in Dunedin with partner Tom Wolfenden and their daughter.
In New Zealand, about 12 per cent of people aged over 50 - 5 per cent of the population - receive state-funded vitamin D supplements. This figure does not include over-the-counter purchases.
In residential care facilities, 74 per cent of elderly residents are given the supplements, which are even more prevalent in the US.