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New evidence Vit D prevents respiratory infections- US study

New evidence that vitamin D prevents respiratory infections

Written by Tim Newman

Published: Thursday 16 February 2017

A large-scale meta-analysis using more than 10,000 participants concludes that vitamin D supplementation may help to prevent a major cause of global death - acute respiratory tract infections.

Could vitamin D supplementation prevent acute respiratory tract infections?

Acute respiratory tract infections are responsible for 10 percent of ambulance and emergency room visits in the United States.

Including anything from the common cold to pneumonia and bronchitis, they were the cause of an estimated 2.65 million deaths globally in 2013.

Respiratory tract infections have a wide array of risk factors, including overcrowding, a damp living environment, air pollution, and parental smoking.

A number of observational studies have also reported a nutritional risk factor - vitamin D deficiency. Some researchers have concluded that vitamin D has the ability to trigger an immune response to certain viruses and bacteria.

However, the links between respiratory tract infections and vitamin D supplementation have remained controversial; some studies support the theory while others are inconclusive. To date, five meta-analyses have been conducted on existing data. Two of these reported significant positive effects, and three found no significant effect.

Diving into the vitamin D data

In an attempt to put this question to bed, the largest meta-analysis to date was published this week in the BMJ.

The analysis, carried out by an international group of researchers, is the first to use individual participant data (IPD), rather than the aggregate methodology that was used in earlier meta-analyses. In this way, changes measured at different points in time within each participant of each trial can be accounted for, rather than taking a summary (aggregate) of the data. IPD is considered the "gold standard" of systematic review.

The team used data from 25 randomized controlled trials investigating vitamin D supplementation. In total, data from 11,321 participants were analyzed.

After adjusting for potentially confounding variables, such as sex, age, and study duration, they found that vitamin D supplementation produced a 12 percent reduction in the proportion of individuals experiencing at least one acute respiratory tract infection.

In simple terms, if 33 people took vitamin D supplements, one acute respiratory tract infection would be prevented. If these results are confirmed, vitamin D supplementation could potentially prevent millions of respiratory infections each year.

Conclusions from the data

When the team drilled further into the data, they found that the positive effect was more pronounced in participants who took daily or weekly vitamin D without additional large doses. The effect was also stronger for individuals with more severe vitamin D deficiencies - only 1 in 4 people in this group would need to take vitamin D regularly to prevent one acute respiratory tract infection.

The authors concluded that:

"Our results add to the body of evidence supporting the introduction of public health measures such as food fortification to improve vitamin D status, particularly in settings where profound vitamin D deficiency is common."

The team also concluded that vitamin D was safe to consume as a supplement; side effects were rare.

Although the thorough statistical methodology and large group of participants give the findings a degree of strength, there are limitations and some researchers remain unconvinced of the effect.

In an editorial published in the same journal, Mark Bolland from the University of Auckland in New Zealand and Alison Avenell from the University of Aberdeen in the United Kingdom, write that the results are "heterogeneous and not sufficiently applicable to the general population. We think that they should be viewed as hypothesis-generating only, requiring confirmation in well-designed adequately powered randomized controlled trials."

The editorial also states that:

"Current evidence does not support the use of vitamin D supplementation to prevent disease, except for those at high risk of osteomalacia (weak bones and muscles due to low blood vitamin D levels, currently defined as less than 25 nanomoles per liter)."

Although the jury remains out, the recent findings have added fuel to the fire. If further trials back up the hypothesis, vitamin D supplementation could provide a cost-effective way of reducing the number of acute respiratory infections on a global basis.

Please note: Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.

9 Replies

Very interesting Tryfan and its good to have anything like this brought to our attention. Its then up to each individual to make of it what they will.


I take 20000 vit d3 once a week i found out i was low in it and the weird thing is since being on it my breathing is a lot better on the day i have it. And loads of energy. I also take b12 and magnesium as well. As for infections i still get them lol. But as with lung conditions thats our weakness i guess.


Sounds like it is working for you at some level at least. I have read recently that increasing magnesium which you are doing is also of great benefit.

Good luck. Hope you continue to improve. Just a thought one more suggestion. I have replaced butter and margarine with Olive Oil. Took a bit of getting used to, especially on toast, but couldn't go back now. Proved to be excellent for cardiac health.


Yeah i have dairy free marg (havent had butter for decades since i was a kid on toast lol)and use olive oil and spray olive oil /coconut oil for cooking. Also got a george to get all excess fat off food m drink rice/oat milk. And eat smoothies with fruits and kale/greens/spinach in. Also use protein powders like spirulina for iron and put flax seed and chia and hemp seed on salads/cereal for protein and take a probiotic. Dear god i sound like a holland and barrett representative lol. Im not btw 😊

I still get broncitis n infections and this winter has been one of the worst but at least when im ill or on steroids/and/or antibiotics i dont get that rough period on and off them too much 👍🏻

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That makes me a bit sad as I have sarcoidosis; If you do have sarcoidosis, please be aware the Royal Brompton Hospital webpage says under ....

Can I take vitamins and supplements?

You should avoid taking vitamin D, as this vitamin is produced in excess by sarcoid granulomas. Unless osteoporosis is present, we normally recommend also avoiding calcium supplements, although this can be discussed on a case-by-case basis.


Hi Sarcoid

Sorry to read your reply. Even more sorry that it may not help you. I do search on USA web sites, they are often more forthcoming with updates. If I find any that are relevant I'll be certain to post them. I'm not a medic so I post with no assurance and the footnote is usually yo speak with your own professional.


Hi I am starting to take vit d supplament as my vit d blood test showed that my level was low

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I have been diagnosed with Lupus in 2006 and 2007 was told it has damaged my lungs (pulmonary fibrosis). I have to use factor 50 sun block during the summer even though I am black.

2014 I decided to ask my Rheumatologist if I could have a blood test to check my vitamin D level and I was shocked when the result game back and I was only 10 instead of a much higher figure. I was started on daily vitamin D and told I have to take it always.

I have not noticed any difference in me not having respiratory infections since taking the vitamin D meds. This winter I have already had three lots of antibiotics caused by respiratory infections.


As I have RA, OA and Osteoporosis as well as Bronchiectasis with pseudomonas (among other things, I take Adcal D3. I have noticed my lungs have been less troublesome.

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