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Vitamin D supplements not proven to prevent disease – study cautions against overuse


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25 Nov 2016

Current evidence does not support the use of vitamin D supplements to prevent disease, a study published in BMJ has concluded.

Researchers from the University of Auckland, New Zealand and the University of Aberdeen, Scotland found that there is a lot of uncertainty surrounding the benefits of the supplementation.

They wrote that patients without a high risk of deficiency should obtain their vitamin D from a healthy diet and regular short bursts of sunshine. They should not be offered supplements.

Patients at high risk of deficiency should only be given a low dosage of the vitamin on an individual basis and equally encouraged to boost their stores through diet and sun exposure, they said.

Public Health England (PHE) currently advises that everyone should consider a 10μg daily vitamin D supplement during the autumn and winter months.

And more than 30-50% of older people in some Western countries take vitamin D supplements, according to the study.

A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain and tenderness due a condition called osteomalacia in adults.

When there is little sunshine, vitamin D can only be obtained naturally through foods such as oily fish, egg yolk, red meat, liver, fortified breakfast cereals and fat spreads.

Based on a comprehensive search of published evidence, the new study make the case that existing clinical trials show that vitamin D supplements do not improve musculoskeletal outcomes, such as falls or fractures.

It also says there is no high quality evidence to suggest that vitamin D supplementation is beneficial for other conditions such as heart disease, stroke, and some cancers.

The only benefits to vitamin D supplementation are most likely to be seen in severely deficient populations, the authors said. “Otherwise we conclude that current evidence does not support the use of vitamin D supplementation to prevent disease,” they conclude.

In a BMJ article, Louis Levy, head of nutrition science at Public Health England and Tim Spector, Professor of genetic epidemiology at King’s College London have debated whether PHE’s advise on vitamin D supplements is valid.

Levy argued that taking 10μg of vitamin D a day is backed by a Scientific Advisory Committee on Nutrition (SACN) review of the evidence on musculoskeletal health outcomes.

He said: “Bolland and his colleagues conclude that serum 25- hydroxyvitamin D should not fall below 25 nmol/L, just like the Scientific Advisory Committee on Nutrition did earlier this year.

“To achieve this, PHE advice includes getting short bursts of summer sun and a balanced diet through summer and spring. But when the days are darker and shorter and sun exposure is minimal, people should consider a daily 10 microgram vitamin D supplement, as it’s difficult to get enough through diet alone.”

He argues that taking 10μg of vitamin D daily to prevent musculoskeletal ill health “is unlikely to result in harmful levels of vitamin D” and says getting enough vitamin D is particularly important “because poor musculoskeletal health remains in the top 10 causes of disability adjusted life years.”

However, Spector said: “We have a strange love affair with vitamin supplements that makes the recent UK government message that everyone should take vitamin D in winter an easy sell. But is this recommendation evidence based?

“With a fifth of the population reported to have low levels is this a real modern epidemic or a pseudo-disease? Will tablets cure us or prevent problems and, importantly, are they completely safe?”

He noted that, despite hundreds of studies, “highly convincing evidence of a clear role of vitamin D does not exist for any outcome.”

Although vitamin D treatment still has a role in people with proved deficiency or in high-risk groups, “the rest of us should avoid being ‘treated’ for this pseudo-disease, save scarce NHS resources, and focus on having a healthy lifestyle, sunshine, and a diversity of real food,” he said.


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