Skip to main content

Vitamin D supplements prevent acute respiratory infections

- that cause many sick days and even deaths

Vitamin D supplements prevent acute respiratory infectionsVitamin D supplements prevent colds, influenza, and intercurrent complications. This was seen in a large meta-analysis emphasizing that vitamin D is not only important for bone health but also for the immune system, which may require larger quantities. Because many old people or weakened individuals die of pneumonia, supplementing with vitamin D may potentially save millions of lives.

It is not a coincidence that many people contract viral infections during the winter period. The sun is our primary source of vitamin D but during the cold months, the sun sits too low in the sky for us humans to be able to use it to synthesize vitamin D in our skin. There is also evidence suggesting that regular multivitamins are unable to cover the actual need for vitamin D, at least if the goal is to make the immune system function optimally. Too much time spent indoors, overweight, type-2 diabetes, ageing processes, and the use of cholesterol-lowering medicine all add to the risk of having a vitamin D deficiency, not just during the winter but all year around.

  • Acute respiratory infections are the leading cause of death worldwide
  • 10% of acute hospitalizations are due to respiratory infections (in the United States)
  • An estimated 2.65 million people died of respiratory infections in 2013                                                                                                 

Final clarification of conflicting results

The meta-analysis was completed at the Queen Mary University in London and is based on analyses of data from around 11,000 participants from 25 clinical studies that were conducted in 14 countries, including Great Britain, Sweden, Italy, the United States, Canada, Japan, India, Australia, and Afghanistan. It revealed that the use of vitamin D supplements has led to different and conflicting results in various studies, and we finally know why. It turns out that especially the groups that had low vitamin D levels to begin with benefited the most from taking vitamin D.
The meta-analysis is published in BJM (British Journal of Medicine), one of the leading science journals, and clearly shows how effective vitamin D supplements are, even compared with vaccination.
50% lower risk of respiratory infections
According to lead researcher, Professor Adrian Martineau, the meta-analysis is a comprehensive study that confirms with certainty that large quantities of vitamin D protect against infections in the airways. The greatest effect is seen in people who use these supplements daily or on a regular basis.
Vitamin D supplements are able to reduce the risk of acute respiratory infections by 50% in people who have low vitamin D levels in their blood to begin with.

How vitamin D protects against respiratory infections, bronchitis, and asthma

The respiratory tract harbors large quantities of white blood cells that depend on vitamin D to carry out their “first-line” attacks on virus and other microbes to protect us against contamination. Vitamin D also protects against respiratory infections by stimulating circulating white blood cells in the blood and boosting levels of antibiotic peptides in our lung tissues.
Vitamin D can even protect against bronchitis and asthma by means of two other mechanisms – strengthening the immune system and counteracting undesirable inflammation.

Many people mistakenly believe that…

we humans are able to produce vitamin D during the winter and early spring if we are in the sun. This, however, is a myth because the sun sits too low in the sky at that time of the year.        

Vitamin D deficiencies are widespread during the winter

The meta-analysis revealed that colds and influenza are common at these latitudes during the winter and in the spring where levels of vitamin D are the lowest. This is because the sun sits low in the sky and because our vitamin D reserves are nearly empty. In addition, the ability to utilize vitamin D varies from person to person, and genes are also known to play a role.

At least as effective as flu vaccines

Acute respiratory infections such as cold and influenza are some of the most common reasons why people see their doctor and stay home from work. Although pneumonia is less common, it is a leading cause of death among older people, cancer patients, and other groups of individuals with compromised health. According to the above-mentioned study, it is therefore obvious to add vitamin D to our food or take strong supplements in the northern countries where vitamin D deficiencies are most common. The meta-analysis even revealed that vitamin D supplements were every bit as effective as flu vaccines.
It should be added that a strong immune system protects against a wide spectrum of microbes, while flu vaccines only target one type of flu virus. Because there are numerous types of flu virus, and because flu virus has always had the ability to mutate, the flu vaccine may easily become ineffective. Also, there are known side effects of these vaccines.

A blood sample can show the body’s vitamin D status

Vitamin D levels in the blood are measured as 25-hydroxyvitamin. The official threshold values are 50 ng/ml, but leading experts believe that this is insufficient and recommend levels as high as 75-100 ng/ml for optimal disease prevention.

How much vitamin D do we really need?

When we sunbathe and expose the entire body to sunlight, it is possible to synthesize 100 micrograms of vitamin D in the skin in less than half an hour. 10 minutes of sun exposure to the face and hands can produce 30 micrograms of vitamin D in the same amount of time. Many researchers claim that the need for vitamin D is far more than the reference intake (around 10 micrograms/day) and lies somewhere in the range of 30-100 micrograms daily.

Vitamin D deficiency and poor utilization may be caused by:

  • Too little sun exposure during the summer period
  • Hyped fear of the sun
  • Veiling and dark skin
  • Vegetarian and vegan diets
  • Too much calcium from dairy product and supplements
  • Alcoholism
  • Overweight and type-2 diabetes
  • Old age and thin skin
  • The use of sun screen with a factor higher than 8 (it blocks the vitamin D synthesis)                                                   
  • Prolonged use of cholesterol-lowering medicine and certain other drugs                                                                                                           


Martineau Adrian et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. The BMJ 2017

University of Colorado Anschultz Medical Campus. Vitamin D reduces respiratory infections. ScienceDaily November 2016

  • Created on .