Vitamin D, the cure-all supplement that could be bad for your health

It is called "bottled sunshine" and claimed to be one of the most effective health supplements on the market. Scores of studies have suggested that it protects against heart disease, cancer, diabetes, high blood pressure, schizophrenia and multiple sclerosis, and a growing number of doctors have recommended it to their patients.

But vitamin D, it turns out, has been oversold. After reviewing more than 1,000 research papers, the authoritative Institute of Medicine in the US has concluded that the high levels often recommended are unnecessary and could even be harmful.

Over recent years the idea that everyone needs extra vitamin D has swept countries on both sides of the Atlantic as scientists and doctors, convinced by the growing body of evidence of the nutrient's role in a range of diseases, have advocated supplements.

Vitamin D is made naturally in the body from sunlight, which is its main source. It is also found in limited quantities in some foods such as fish and fortified breakfast cereals. As much as half the population is said to have less than optimum levels.

The gloomy weather and long winter in countries north of 30 degrees latitude, such as the UK, means that a large part of the earth's population is deficient between October and March.

In the US, sales of vitamin D supplements soared 80 per cent in 2008-09 to $430m (£270m). In 2001 they stood at $40m. Requests for blood tests for vitamin D levels from one company, Quest Diagnostics, surged 50 per cent in the fourth quarter of 2009 alone.

But according to the IoM, the excitement got ahead of the science. Dennis Black, professor of epidemiology at the University of California and an author of the report, said: "Everyone was hoping vitamin D would be kind of a panacea. The number of vitamin D tests has exploded."

The IoM has now sought to quell the craze. The 14-member expert committee, convened at the request of the US and Canadian governments, was widely expected to increase the recommended blood level of the vitamin, last set in 1997 and based on what was necessary for bone health. Vitamin D is essential for building bones and deficiency in children causes rickets.

Experts had said that the emerging evidence of its role in other diseases meant that the recommended blood level should be increased. But the IoM has rejected the evidence and said that most people are getting enough of the vitamin from sunlight and diet.

"This review found that information about the health benefits [of vitamin D] beyond bone health were from studies that provided often mixed and inconclusive results and could not be considered reliable," the committee said. They recommend people need 600 international units a day (800 a day over age 70) and warn that doses above 4,000 units a day may be harmful. Vitamin D supplements containing 5,000 units per pill are widely available in the US, and can also be bought in the UK.

"Very high levels of vitamin D (above 10,000 IUs per day) are known to cause kidney and tissue damage. Some preliminary studies offer tentative signals about adverse health effects [at lower levels]", they add.

Oliver Gillie, of the UK Health Research Forum, said there was a greater need for vitamin D supplementation in the UK because of our poorer weather and fewer vitamin D enriched foods.

"American adults are already getting about 300 international units from sun and fortified milk and orange juice, whereas in the UK we get an average of only 150 IUs per day from all sources. So this means we need to take 450 IUs per day to fall in line with the IoM recommendation," he said.

Life and Style
ebookNow available in paperback
ebooks
ebookPart of The Independent’s new eBook series The Great Composers
Arts and Entertainment
Buttoned up: Ryan Reynolds with Helen Mirren in ‘Woman in Gold’
filmFor every box-office smash in his Hollywood career, there's always been a misconceived let-down. Now he says it's time for a reboot
News
people
News
Actress Julianne Moore wins the Best Actress in a Leading Role Award for 'Still Alice' during the 87th Annual Academy Awards in Hollywood, California
people
Sport
Ross Barkley
footballPaul Scholes says it's time for the Everton playmaker to step up and seize the England No 10 shirt
News
'We will fix it': mice in the 1970s children’s programme Bagpuss
science
Life and Style
2 Karl Lagerfeld and Choupette
fashion
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Recruitment Genius: Customer Service Executive

    £18000 - £22000 per annum: Recruitment Genius: This is an exciting opportunity...

    Recruitment Genius: Retail Buyer / Ecommerce Buyer

    £30000 - £35000 per annum: Recruitment Genius: Working closely with the market...

    Recruitment Genius: Sales Executive - CAD Software Solutions Sales

    £20000 - £50000 per annum: Recruitment Genius: A reputable company, famed for ...

    Ashdown Group: Client Accountant Team Manager - Reading

    Negotiable: Ashdown Group: The Ashdown Group has been engaged by a highly resp...

    Day In a Page

    War with Isis: Iraq declares victory in the battle for Tikrit - but militants make make ominous advances in neighbouring Syria's capital

    War with Isis

    Iraq declares victory in the battle for Tikrit - but militants make make ominous advances in neighbouring Syria
    Scientists develop mechanical spring-loaded leg brace to improve walking

    A spring in your step?

    Scientists develop mechanical leg brace to help take a load off
    Peter Ackroyd on Alfred Hitchcock: How London shaped the director's art and obsessions

    Peter Ackroyd on Alfred Hitchcock

    Ackroyd has devoted his literary career to chronicling the capital and its characters. He tells John Walsh why he chose the master of suspense as his latest subject
    Ryan Reynolds interview: The actor is branching out with Nazi art-theft drama Woman in Gold

    Ryan Reynolds branches out in Woman in Gold

    For every box-office smash in Ryan Reynolds' Hollywood career, there's always been a misconceived let-down. It's time for a rethink and a reboot, the actor tells James Mottram
    Why Robin Williams safeguarded himself against a morbid trend in advertising

    Stars safeguard against morbid advertising

    As film-makers and advertisers make increasing posthumous use of celebrities' images, some stars are finding new ways of ensuring that they rest in peace
    The UK horticulture industry is facing a skills crisis - but Great Dixter aims to change all that

    UK horticulture industry facing skills crisis

    Great Dixter manor house in East Sussex is encouraging people to work in the industry by offering three scholarships a year to students, as well as generous placements
    Hack Circus aims to turn the rule-abiding approach of TED talks on its head

    Hack Circus: Technology, art and learning

    Hack Circus aims to turn the rule-abiding approach of TED talks on its head. Rhodri Marsden meets mistress of ceremonies Leila Johnston
    Sevenoaks is split over much-delayed decision on controversial grammar school annexe

    Sevenoaks split over grammar school annexe

    If Weald of Kent Grammar School is given the go-ahead for an annexe in leafy Sevenoaks, it will be the first selective state school to open in 50 years
    10 best compact cameras

    A look through the lens: 10 best compact cameras

    If your smartphone won’t quite cut it, it’s time to invest in a new portable gadget
    Paul Scholes column: Ross Barkley played well against Italy but he must build on that. His time to step up and seize that England No 10 shirt is now

    Paul Scholes column

    Ross Barkley played well against Italy but he must build on that. His time to step up and seize that England No 10 shirt is now
    Why Michael Carrick is still proving an enigma for England

    Why Carrick is still proving an enigma for England

    Manchester United's talented midfielder has played international football for almost 14 years yet, frustratingly, has won only 32 caps, says Sam Wallace
    Tracey Neville: The netball coach who is just as busy as her brothers, Gary and Phil

    Tracey Neville is just as busy as her brothers, Gary and Phil

    The former player on how she is finding time to coach both Manchester Thunder in the Superleague and England in this year's World Cup
    General Election 2015: The masterminds behind the scenes

    The masterminds behind the election

    How do you get your party leader to embrace a message and then stick to it? By employing these people
    Machine Gun America: The amusement park where teenagers go to shoot a huge range of automatic weapons

    Machine Gun America

    The amusement park where teenagers go to shoot a huge range of automatic weapons
    The ethics of pet food: Why are we are so selective in how we show animals our love?

    The ethics of pet food

    Why are we are so selective in how we show animals our love?