Dr Sarah Brewer, GP and Medical Director of Healthspan:

“The study by Queen Mary University of London reinforces the government’s advice to take a daily vitamin D supplement. The government recommendation of 10mcg per day is based on the minimum dose required to avoid diseases related to vitamin D deficiency, such as rickets. Most health professionals recommend higher levels, between 20–25mcg per day, which will help to support the immune system.”

Vitamin D is making the headlines more and more – barely a week goes by without another study linking to a reduced risk disease.

It’s the also the only supplement the Government recommends we take – especially during winter.

Research has linked the vitamin to a reduced risk of depression, breast cancer and colds and chest infections.

But what is it, how much do we need, and why is it so vital to our health?

Here, leading medical nutritionist Dr Sarah Brewer, and author of Eat Well, Stay Well, explains how vitamin D can benefit the body from head to toe….


Vitamin D regulates the amount of calcium and phosphate in the body, both needed for healthy bones, teeth and muscles.

But research is increasingly showing it has many other health effects – and may protect against a number of diseases.

So if you want to live longer, maintaining a good level of vitamin D in your blood appears to be key.


During spring and summer, the majority of us get enough vitamin D through sunlight on our skin – when the UV index is greater than 3.

But at our northerly latitude, this doesn’t happen during autumn and winter.

And while diet should always come first, vitamin D is only found in a small number of foods such as oily fish, egg yolks, red meat and liver.

It is also added to fortified food like breakfast cereals and fat spreads, but these too are unlikely to provide enough.

This means many of us are in danger of vitamin D deficiency for at least three months of the year.

Official figures show 23 per cent of adults, 21 per cent of the elderly 22 per cent of teenagers have low levels of vitamin D in their blood.

As a result, Public Health England (PHE) recently advised everyone in the UK should take a vitamin D supplement of 10 micrograms (mcg) a day during autumn and winter months.

Up until now, only at-risk groups – including children aged one to five, pregnant and breastfeeding women, adults over 65 and those with darker skins – were advised to take vitamin D daily.


Even if you’re not motivated to take vitamin D for healthy bones in the future, you might consider taking it to prevent a cold this winter – and to potentially help you live longer.


Have you ever wondered why we’re more prone to coughs, colds and respiratory bugs – even pneumonia – during winter than in summer months?

While huddling together indoors may help germs spread more easily, falling vitamin D levels are also to blame for reduced protection.

Vitamin D is involved in the activation of macrophages – the hunter-killer cells that engulf and destroy invading viruses, bacteria and even fungi.

Vitamin D receptors are also present on other immune cells which fight infection and regulate our allergic responses and inflammation.

The vitamin is also involved in the production of antibiotic-like proteins in the cells lining the respiratory tract.

Known as defensins, these proteins stick to bacterial walls and open up holes so bacteria become leaky and implode.

Defensins are also active against viruses. It’s therefore not surprising that people who have low vitamin D levels – especially in winter – are more prone to colds, influenza, bronchitis and even pneumonia.


Even in Victorian times, treatments for serious respiratory infections, such as tuberculosis, included cod liver oil and exposure to UV rich sun at high altitudes (heliotherapy).

Both of these are now known to work by boosting your circulating vitamin D levels.

The evidence that vitamin D can help keep you well in winter is now overwhelming.

A recent analysis of data from 16 clinical trials, involving over 7,400 people, looked at the effects of taking vitamin D versus a placebo on the risk of respiratory tract infections.

Overall, vitamin D supplements significantly reduced the risk of experiencing at least one respiratory infection (common cold, influenza or pneumonia) by 35 per cent during the follow-up periods, which ranged from 3 weeks to 3 years.


Colds and flu are a common trigger for asthma flare-ups – so by protecting against the viruses that cause colds and bronchitis, vitamin D can reduce the risk of an asthma exacerbation.

Researchers have also discovered vitamin D helps to suppress inflammation and boosts the body’s response to the drugs in asthma inhalers (corticosteroids).

A review the Cochrane Collaboration – a gold standard panel of international scientists – found taking vitamin D slashed the risk of asthma patients needing to go A&E or being hospitalised by a massive 61 per cent. It also reduced the need for oral steroids.

This evidence was classed as ‘high quality’ and the authors said it makes sense for everyone with asthma to consider taking a vitamin D supplement.


Having high levels of vitamin D could help women to survive breast cancer, research suggested last week.

Those with increased amounts of the sunshine vitamin were nearly a third more likely to survive the diagnosis.

One theory is the vitamin may help stop the reproduction of cancerous cells, according to the JAMA Oncology report.

Previously, a large analysis of data from 14 studies, involving over 25,000 women, found women with the highest vitamin D levels were less likely to develop breast cancer. The research was reported in the journal Tumour Biology.


People with the highest vitamin D levels are 62 per cent less likely to develop type 2 diabetes than those with the lowest levels.

This was the conclusion of a huge A huge analysis of data from 21 studies, involving over 76,000 people, published in the journal Diabetes Care.

The most likely explanation is that vitamin D improves insulin sensitivity to better regulate blood sugar control.


Most recently, vitamin D deficiency has been associated with depression and low mood – particularly in winter – as our bodies obtain most of our vitamin D via UVB rays from the sun.

And research published in the British Journal Psychiatry found those with the lowest vitamin D levels were up to twice as likely to develop depression as those with highest levels.

In another study, revealed last month at the International Early Psychosis Association in Milan, scientists tested vitamin D levels among 225 patients being treated for psychotic disorders and another 159 well people.

They found a significant association between low levels of vitamin D and ‘higher levels of negative symptoms and of depression’ among people with psychosis.

In a paper in the journal Schizophrenia Research, the researchers, from Norway, suggested vitamin D could be used to help treat patients.


Children conceived between January and March are more likely to have conditions such as autism and dyslexia than those conceived during summer months.

This was the conclusion of Glasgow University scientists after examining more than 800,000 Scottish children

Lead author Professor Jill Pell said lack of vitamin D is ‘The most plausible explanation for the trend’ and urged women to take supplements when trying to get pregnant/during pregnancy.


Higher vitamin D levels may help us live longer, according to research in people aged over 50 published in the BMJ.

Studies carried out in eight countries, involving 26,000 men and women, found those with the highest vitamin D levels were 57 per cent less likely to die from any medical cause during the research durations than those with the lowest levels.


10mcg is the minimum needed to prevent conditions linked with vitamin D deficiency such as muscle and bone aches and pains, osteomalacia (softening of the bones) or rickets.

This is the amount we are advised by Public Health England to take during winter.

While that’s great advice as far as it goes, it doesn’t take into account how important the vitamin is for a strong immune system and protection against many health issues – such as those discussed above.

There’s also increasing evidence some people may need higher doses of 25mcg to 50mcg, particularly the elderly.

If you always use sunscreen, cover up in the sun, have dark skin or are house bound, you may need vitamin D supplements all year round.


Vitamin D supplements are available free-of-charge for low-income families on the Healthy Start scheme.

Otherwise, you need to buy them yourself. Select a supplement made to a pharmaceutical standard known as GMP (Good Manufacturing Practice) to ensure you get a consistent dose.

Look for a supplement supplying the vitamin D3 form, which is more effective at maintaining blood levels than the vitamin D2 form.

Rob Hobson, Healthspan Head of Nutrition says: ‘It’s very hard to get the levels of vitamin D we need from our food and during winter.

‘Therefore, I do recommend people support their diet with a supplement of vitamin D3, which is the same form made by the body on exposure to sunlight. Try Healthspan Super Strength Vitamin D (£9.95 for 240 tablets).’


Intakes of up to 100mcg vitamin D per day are not associated with adverse effects.

Higher doses are best taken under medical supervision and tailored to your blood levels.

But be aware excess can lead to side effects associated with high calcium levels, such as demineralisation of bone, kidney stones, headache and muscle weakness.

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