Vitamin D May Not Reduce Common Cold Risk

A new study suggests that vitamin D supplementation may not reduce the risk or severity of the common cold.

The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones. It is used, alone or in combination with calcium, to increase bone mineral density and decrease fractures. Recently, research also suggests that vitamin D may provide protection from osteoporosis, hypertension (high blood pressure), cancer and several autoimmune diseases.

In a new study, researchers randomly assigned 322 healthy adults to one of two groups. The first group received one dose of 200,000 IU vitamin D3 by mouth, a second dose of 200,000 IU one month later, and then 100,000 IU once monthly for 18 months. The second group received a placebo in the same frequency as the vitamin D group. The development of the common cold was the main outcome measure. Severity and duration of cold symptoms were also evaluated.

The researchers found that a significant difference between the number of colds in the vitamin D and placebo groups was lacking, with 593 and 611 colds in the vitamin D and placebo groups, respectively. Furthermore, the severity and duration of cold symptoms was similar between groups.

The authors concluded that vitamin D supplementation may not reduce the risk or severity of the common cold. Additional research is necessary.

In addition to vitamin D, many other integrative therapies have been studied for their potential to reduce the risk, severity and duration of the common cold. There are conflicting results regarding the effect of zinc formulations in treating the duration and severity of common cold symptoms. Although zinc may be beneficial in the treatment of cold symptoms if taken at the onset of symptoms, more studies are needed to clarify which zinc formulations may be most effective, which rhinoviruses are affected by zinc and if nasal sprays provide a useful alternative application route for zinc treatment.

Scientific studies generally suggest that vitamin C does not prevent the onset of cold symptoms. However, in a subset of studies of people living in extreme climates or under extraordinary conditions, including soldiers in subarctic exercises, skiers and marathon runners, vitamin C significantly reduced the risk of developing colds, by approximately 50 percent.

For more information about integrative therapies for common cold treatment and prevention, please visit Natural Standard's Comparative Effectiveness Database.

For more information about vitamin D, please visit Natural Standard's Foods, Herbs & Supplements Database.

Comments

[ac]

I actually hadn’t heard too much about vitamin D reducing the risk of cold. You usually hear of vitamin C or zinc being recommended, usually contained in products such as airborne or cold-eeze. Although, it is still unclear whether vitamin C really does help with preventing cold.

[kj]

It is crucial to relay to patients that there is no cure/treatment for the common cold. it is a virus, not a bacteria. OTC drugs are used to target symptoms. So when a patient comes in asking for products, you must ask exactly what their complaints are and select products based on that. Seek medical attention if there is a fever of 102 degrees Fahrenheit or higher, the fever is accompanied by aches, extreme fatigue, sweating, chills, and a cough with colored phlegm, or symptoms get worse instead of better or last more than 10 days.

[JH]

I didn't know that vitamin D may reduce common cold risk! However I knew, not only vitamin D is to maintain normal blood levels of calcium and phosphorus but also as we increase our consumption of D, we start becoming thinner. Every cell in our body needs D to function properly and special receptors for D signal whether we should burn fat or simply store it. When D plugs into these receptors, it increases our body's fat burning mechanism.

[ML]

I did not even know that vitamin D was thought to reduce the cold. I have heard about vitamin C and teachers from school say that it does not help. But, when I get a cold all I want is a glass of orange juice and chicken noodle soup. Maybe it’s a placebo effect. Even though vitamin D does not reduce the risk of getting a cold, it is still important for the bones.

[kj]

Adding to the confusion, I also have never heard of taking vitamin D for colds. Many patients look for a cure all for the common cold and the advice I like to give is treat your symptoms and drink plenty of fluids. The associated between weather and the common cold is also a misconception. Cold weather doesnt cause colds, and warm weather will not prevent cold including extra sunlight. Giving high doses of vitamins can actually do more harm than good including cardiac problems. This dose (200,000 IU) isnt even given to people who are vitamin D deficient!

[J Squared]

Although this study shows that Vitamin D is not as essential in aiding with colds, it still should not be undermined as a great supplement when it comes to protecting bones and preventing osteoporotic events. In the New England area especially, where winter consumes most of the year, people are more likely to experience Vitamin D deficiencies due to lack of exposure from the sun. I can speak for myself, being deficient in this essential vitamin, that I need supplementation all year long with Vitamin D in order to maintain adequate levels.

[GP]

I too was surprised at this study, because I had never heard of taking Vitamin D to prevent colds. Vitamin C, zinc, Echinacea- yes, but not vitamin D. As far as zinc goes, there have been reports (though not confirmed) of intranasal zinc causing loss of sense of smell, so I personally would not want to try that for cold prevention. However, I do use zinc lozenges when I feel a cold coming on to try and ward it off, or at least lessen its duration. As for vitamin C, I think being deficient in it could definitely weaken a person’s immune system and make them more likely to get a cold. But as long as you get the recommended daily value, that is usually enough to protect most people.

[My Lien]

It is good to see growing research regarding Vitamin D. As a "hot" supplement, we need studies to sort out the evidence from the hype. Thanks to the collaborators at Natural Standards to keep up aware of the latest research.

[kt]

I have not seen Vitamin D linked to the common cold before, I did not realize it was a possible treatment in the past. I wonder about the patients selected for this study - did they have any renal issues or vitamin D levels measured at the beginning of the study? These are very high doses of vitamin D, a vitamin that is fat soluble and therefore potentially a vitamin that one can overdose on. Even here in Seattle where people have lower vitamin D levels due to the lack of sunshine in the cooler months, I don't ever see patients taking 200,000IU in one dose. Are these doses common elsewhere or over inflated for the sake of the study?

[ss]

It is not surprising that investigation of the use of Vitamin D for various ailments has taken off recently but of course, further study is needed. It is most well-known for helping maintain blood levels of calcium and has application in increasing bone health. There is a some controversy over what the optimal levels of the vitamin should be, though most agree “low” D levels can be identified and treated with supplements. This study was ambitious but the sample was small and one should question the mega doses given participants. The article mentions other essential nutrients. Perhaps a new study focusing on a combination of these supplements would yield a more positive result.

[nb]

I was unaware that people took vitamin D for cold prevention. I was under the impression that many people took vitamin C and zinc supplements to reduce cold symptoms or to shorten a cold, although there are conflicting thoughts on the theory. The results of the vitamin D study should not be interpreted as vitamin D supplementation being unnecessary, however; osteoporosis prevention and promoting strong bones and increased immunity is very important in the long run.