Is it time to rethink the pills you pop? A study of nearly 26,000 Americans has revealed that vitamin D pills do not prevent bone fractures.
Experts in New Zealand say the findings support existing evidence that the supplement doesn't offer any benefits for most healthy people.
The researchers determined that vitamin D, taken with or without calcium, has no effect on rates of bone fractures.
Professor Meryl LeBouff from Harvard Medical School, the study's author, said the findings were unexpected.
"We were surprised; we hypothesised that there would be a small effect in terms of a fracture reduction," she said.
Nearly 26,000 American men and women over the age of 50 were given either 2000 units of vitamin D or a placebo for five years. Prof LeBouff, who works at Brigham and Women's Hospital in Boston, said the dosage didn't have any impact.
"It added no additional benefits in terms of decreasing fractures in generally healthy US adults enrolled nationwide."
Distinguished Professor Ian Reid, who is Auckland University's Head of Department Medicine, said there's increasing evidence against the supplement.
"Giving vitamin D to otherwise healthy people really doesn't make any difference to any medical endpoints. Taking lots of extra vitamin D is a waste of time."
Which some Kiwis have already figured out. One elderly man told Newshub he'd never taken any supplements.
"I just try and eat well - plenty of fruit and vegies, things like that. Stay away from the fatty stuff."
Another said he researched Vitamin D, which indicated it wasn't worth it.
"Money down the drain," they described it.
Vitamin D can help to regulate your mood, boost immunity and increase absorption of calcium. However, the latest research suggests most of us are already getting enough from the sun and we don't need extra supplements.
"The vitamin D that you manufacture through the summer gets stored up so in most cases tides people through the winter," said Prof Reid.
However, he said there are some people who might still need a top-up.
"Frail elderly who never get outside, a supplement is a very sensible thing. People with very dark skin living in relatively sunless environments, it's very important."
For the rest of us, a dose of sunlight could be all we need.