Health

Why scientists say official advice to take Vitamin D is bunkum

EVERY man, woman and child above the age of five should think about taking Vitamin D pills from October to March, every year – or so said Public Health England in a 2016 recommendation, in order to ‘help keep healthy bones, teeth and muscles’.

The edict followed Government- backed research from the Scientific Advisory Committee on Nutrition (SACN), which looked at the links between Vitamin D levels and musculoskeletal health, as well as a range of problems including heart disease, type 1 diabetes, cancer and multiple sclerosis. One in five Britons suffered from low levels of the so-called ‘ sunshine vitamin’ – which is essential for healthy bones, among other things – the committee claimed.

Although small amounts can be gained from food, mainly oily fish, offal and eggs, Vitamin D is actually a hormone, primarily produced by the body, in the skin, in response to UV rays from the sun.

And the British weather, particularly during the winter months, prevents much of the population from generating healthy amounts, said the researchers.

At the time, many doctors welcomed this ‘sea change’ in thinking, believing it would help protect public health. And unsurprisingly,

demand for supplements soared. Supermarket industry analyst The Grocer reported that sales leapt by a third, with Britons spending more than £7 million on Vitamin D pills last year.

So a report earlier this month in worldrenowned medical journal The Lancet that suggested Vitamin D supplements did not improve bone strength came as a surprise.

In fact, more than 30 new research papers have been published since the SACN study, casting doubt on their findings. And there has been growing disquiet in the scientific community with some suggesting the recommendations amounted to little more than pseudo-science.

More worryingly, reports have also begun to surface of ‘overdoses’ of supplements: Vitamin D can build up inside the body.

Although rare, high levels can lead to fatigue, muscle and joint pain, memory loss, painful kidney stones and – paradoxically – a risk of bone problems and fractures.

Some researchers are even calling for the Public Health England guidelines to be reversed. So just how did Vitamin D lose its shine?

WHO REALLY IS VITAMIN D DEFICIENT?

WE ALL need Vitamin D. Without it, we cannot absorb calcium, which leads to bone-thinning and risk of fractures.

A deficiency of it causes rickets in children and osteomalacia in adults, both of which are a softening and weakening of the bones along with pain and deformities.

In children with rickets, the Vitamin D deficiency manifests itself as a characteristic bowing of the leg bones as they grow.

Though descriptions of rickets first appeared in the Roman era, it was a particular scourge of Victorian times, due largely to lack of sunlight in smog-ridden industrial towns.

Cleaner air and better nutrition all but eradicated the disease, but cases have been reported again, mostly in children of Asian and AfroCaribbean backgrounds who are at greater risk because their darker skin means they do not absorb as much sunlight.

But there is a vast difference between a clinical deficiency that causes rickets or osteomalacia – in which blood levels of Vitamin D are likely to be virtually undetectable – and ‘low Vitamin D’ cited by SACN that may not actually be of much concern anyway.

Levels of Vitamin D in the body can be determined via a blood test. The chemical measured in the blood is called 25-hydroxy-vitamin D, and the results are reported in units of nanomoles per litre (nmol/l).

The Department of Health defines low Vitamin D as having a level of 25 nmol/l. This figure was set about 20 years ago, at a level above which no risk of rickets could be identified.

However, it is not, and never has been, a diagnostic clinical threshold: dipping below this score does not indicate illness or disease.

Doctors do not know how low levels have to be, or for how long, to cause health problems.

Public Health England recommends we take a daily 10 microgram (written on bottles as μg or mcg) Vitamin D supplement in winter. This dose was calculated to make sure the vast majority of us achieve a 25 nmol/l blood level. The current number who fall below this level is about one in five.

HOW MUCH DO WE ACTUALLY NEED?

JUST as there is no firm consensus on deficiency, there is even less known about what may be an optimal level. In America, a 2010 report from the Institute of Medicine ruled that a Vitamin D level of 50 nmol or higher was ‘adequate’ for good bone health. Subsequently, a level below 50 came to be considered a Vitamin D deficiency.

But in a 2013 article in the New England Journal of Medicine, several of the scientists who were on the original Institute committee argued for a lower cut off for Vitamin D deficiency of 30 nmol/l.

The US Endocrine Society has gone the other way and recommends really quite high blood levels – between 100 and 150 nmol/l – ‘to guarantee sufficiency’.

Tim Spector, a Professor of Genetic Epidemiology at King’s College London, says too many people are being told they need a Vitamin D supplement, based on a quite arbitrary assessment of what constitutes an adequate level.

‘At a population level it makes a huge difference where you set cutoff levels – just a small difference in the figures can mean millions being medicalised with a Vitamin D deficiency when in fact they have nothing of the sort,’ he says.

‘If your level is below 10 nmol/l, generally accepted as clinical deficiency in most countries, it’s quite clear-cut. You begin to get Vitamin D deficiency symptoms, so that would definitely be a reason to take a supplement.

‘In my view, between 10 and 30 nmol/l is a grey area as to whether you’d suggest supplements. Above you are probably fine. But most labs offering testing suggest blood levels