And there is much debate about the health benefits of vitamin supplements, organic food and alternative medicines, let alone different forms of spirituality.
"People are reaping protective benefits from vitamin E simply by taking a multivitamin, " said neurologist and study author Dr. Richard Benson of CPMC.
Certain dietary supplements such as vitamin D and fish oil have proven benefits, but others like bitter orange and vitamin B5 lack evidence.
As new studies continue to showcase vitamin D's potential benefits, more scientists are calling for increased recommendations.
However, the IOM said it wasn't clear there were other health benefits linked to vitamin D and warned people from consuming too much.
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Higher prices for fresh fruits and vegetables, the demand for which is elastic, reduces consumption, so consumers get less of the antioxidant, vitamin and high-fiber benefits that these products afford.
But the result is still surprising, because other recent studies, some of them even larger, have concluded that vitamin supplements do not provide any significant health benefits.
Vitamin supplements cost next to nothing and bring lifelong benefits.
John Neate, chief executive of The Prostate Cancer Charity, said it was not the first study looking at vitamin D in the disease but a consensus on the benefits had not been reached.
And late last year, the Advertising Standards Authority also criticised the company's promotional style for the product, Glaceau Vitamin Water, saying it presented "misleading" claims about nutritional benefits.
Recent research has suggested that vitamin C, vitamin B-6 and vitamin B-12 don't deliver all of their purported health benefits.
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