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TAKING EXTRA VITAMIN D can protect against colds, flu and other respiratory infections, according to a new study which has reopened a debate on the usefulness of over-the-counter supplements.
A review of 25 clinical trials in 14 countries, some with conflicting results, yielded “the first definitive evidence” of a link between vitamin D and flu prevention, researchers claimed in The BMJ medical journal.
The effects were strongest for people with very low levels of the nutrient which is found in some foods and can be synthesised by the body when the skin is exposed to ultraviolet light.
Many people, especially in grey, cloudy climes, do not have enough vitamin D.
Scientific studies over the years have delivered contradictory conclusions on the topic.
Some have shown that low levels of the vitamin increase the risk of bone fractures, heart disease, colorectal cancer, diabetes, depression, Alzheimer’s disease and death.
Others said there is no evidence of a link to disease risk.
New study
For the new study, researchers from the Queen Mary University of London conducted the biggest-ever survey of trials involving nearly 11,000 people.
And they found clues as to why supplements seem to work in some trials but not in others.
“The bottom line is that the protective effects of vitamin D supplementation are strongest in those who have the lowest vitamin D levels, and when supplementation is given daily or weekly rather than in more widely-spaced doses,” lead researcher Adrian Martineau said in a statement.
Vitamin D is thought to protect against respiratory infections, including bronchitis and pneumonia, by boosting levels of antibiotic-like peptides in the lungs, said the team.
This fits with an observation that colds and flu are more common in winter and spring, when vitamin D levels are lowest.
It may also explain why vitamin D seems to protect against asthma attacks, they said.
In an editorial published with the study, experts Mark Bolland and Alison Avenell said it should be viewed as a hypothesis in need of scientific confirmation.
Louis Levy, head of nutrition science at Public Health England, shared their caution.
“This study does not provide sufficient evidence to support recommending vitamin D for reducing the risk of respiratory tract infections,” he said via the Science Media Centre in London.
Other observers were more optimistic.
The case for universal vitamin D supplements, or food fortification, “is now undeniable,” concluded Benjamin Jacobs of the Royal National Orthopaedic Hospital.
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Anybody living in Ireland should be on a vitamin D supplement all year round anyway. We don’t get enough sunlight. There’s also a proven link between a lack of vitamin D and depression.
There is enough sun, but we just don’t go out in it. As with any study, it’s only valid if it’s repeatable and reviewed. In this case, the evidence on vitamin D and infection is inconsistent and this study does not provide evidence to support recommending vitamin D for reducing the risk of infections. I know this is being leapt upon by both charlatan supplement companies and those that add it to products (orange juice, cereals), but the key point is that if you don’t get enough sunlight, then eat fatty fish, cheese or else cornflakes etc.. what you don’t do is take the over the counter supplements and avoid natural sources. And never forget the main source for everyone, facing the sun.
@Gulliver Foyle: it certainly works for me and it is not a placebo effect. We are at such a Northern latitude that we only get Vitamin D3 from sunlight from April to October and only if we get unprotected sunlight in the middle of the day.
I was a coughing wheezebag and prone to every infection. Life was miserable for me. I had a few scary respiratory arrests.
A young GP suggested to me that I might try Vitamin D3 supplements. I did and the effect was extraordinarily good. I had started to look ‘very shook” and unwell. My wife could see that I was in decline. Then after Vitamin D3, all of these infections stopped. Correlation is not causation but VitaminD3 works for this one person. I look better, feel better, I pick up no infections and my breathing is transformed.
I’m opposed to quackery but I know more than a few GPs who regard Vitamin D3 supplementation as the only required supplementation in Ireland.
@Gulliver Foyle: and certain,y not enough sunlight from November to March unless you can afford a few winter sun holidays.
I’m open to correction but doesn’t vitamin D require sunlight (UV rays) for activation? Anecdotally, I had a friend who was fatigued and the doc was asking if she took vitamin D, when she said yes, he prescribed sunbeds. Saw her a few weeks after and she was utterly rejuvenated. Between work and nightclasses and study at weekends, she saw no sunlight.
@Gulliver Foyle: You’ve made a few dodgy observations there. 1. There simply is just not enough sun, we live in a climate that is mostly overcast and cloudy. Also how does someone who works in an office and maybe commutes home, just “go out in it”? 2. The study is a peer reviewed study. There is plenty of other supporting evidence and research to back it up, it’s just that major drugs companies don’t fund this kind of research so it’s harder to find new work. But it’s old news and has been long understood that vitamins generally are essential to the human body. It’s been in every biology book since the 1700s. If you told a bunch of sailors 400 years ago that adding lime juice to their diets would prevent scurvy, they’d have the same reaction as you. 3. What prey tell is the difference between a naturally sourced molecule of vitamin D and a supplemental vitamin D molecule? Yes get as much sunlight as possible, eat more fish etc. But for most Irish people, that won’t be enough.
Close, vitamin D from cholesterol can only be activated by UVB light but dietary vitamin D is activated by enzymatic conversion.
Some good points there, but the observations aren’t dodgy, they were the result of the peer reviews of the paper where the was a clear difference in the interpretation of results, and that is being pushed by the reports on it (I.e. vitamin d stopped respiratory illness in 1 in 20, but the vehicle for these was not in over the counter supplements). The available sunlight here is sufficient for 80% of vitamin d needs, but we are deficient because we do not have a culture of sunlight absortion, and excuses like “I’m on the bus” need to be countered by getting out more. In more northern places, they are like penguins in the sun at lunchtime, whereas places where they don’t do this (like Finland and Ireland) have higher rates of bone issues in older people. On point 3, there is a clear difference between vegetable extract based supplements and those that actually work to increase d3 utilisation (new studies every year the uselessness of these supplements). The point I was making is that the vitamin that the first commenter mentioned that helped him, should only be used when there is an issue in diet and sun absortion, but not used solely as a replacement.
If that 80% was spread over 12 months then you might have a point but it’s not. That’s actually half the problem, we go from nearly none to 80% of our recommended allowance at different times of the year. There’s no consistent level
I suffered terribly with colds, flus, respiratory infections, even to getting bilateral pneumonia.
About 3 years ago, a young GP said to me that I should consider Vitamin D3 supplementation. I tried it. No more colds, flus or problems, no more antibiotics and Infeel far more vigorous.
Come April, I make sure that I get unprotected sunlight in the middle of the day.
For older people such as me, Vitamin D3 absorption is insufficient.
Sunlight is best but supplementation is a good back up.
Midday sun, 10′minutes, unprotected by sun barriers on the torso and arms is good but don’t scrub off in a shower or bath. Allow 48 hours fir the UV radiation to operate on the skin secretions so as to produce the Vitamin D3 on the skin and to absorb into the subcutaneous fat.
Unfortunately, we only get enough sunlight from April to October and generally only in the middle Of the day.
What are those teeth rotting cereals doing there?
So do we still need to be vacinated against the winter bug?
@cryptoskitzo: If you mean the flu vaccine, then yes. Vitamin D may help some people if they have very low levels, but only a vaccine can prevent flu in most people. Yes, I know, the flu vaccine is not 100% effective, that’s not the point. It still helps in many cases. The problem is there are so many variations of the flu virus, the vaccine can only prevent the main 3 or 4 varieties circulating in each year. That’s still worthwhile.
Vitamin D supplementation has proliferated in the U.S in recent years. Problem here is twofold. Very low sunlight levels between Oct and April and when people do get out they use sunblock. Sunblock is a big no no for Vitamin D production . Read a very interesting article recently which shows the prevalence of auto immune diseases increases as one goes North. From practically nothing on the equator to seriously high levels of Lupus, Multiple Sclerosis, Skin conditions like dermatitis etc. > 50degress North.
I used to get 2-3 colds a year every year for as long as I can remember. 3 years ago I started taking cod-liver plus multivitamins in the one tablet and haven’t had a cold since. Don’t know if it’s related but can’t be doing any harm
Count me skeptical! I have been taking a Vitamin D supplement for years and live in a very sunny climate but am now finally getting over a week long flu that floored me.
Very important to remember that Vit D3 is essential to the prevention of osteoporosis…how you get it is up to yourself !! Sun is of course the best….
https://www.ncbi.nlm.nih.gov/pubmed/23739765
If all the food get added vit D then you will get too much of it because you will be getting doses of it from every food then?
If you said that last week many would have laughed at you for saying it???
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