Skip to main content

Remember vitamin D to prevent infections

Remember vitamin D to prevent infectionsMore and more people boost their immune with help from Echinacea, ginger, smoothies, and juices packed with vitamin C, antioxidants and secondary immune-strengthening compounds. Nonetheless, none of these otherwise useful strategies can compensate for the widespread lack of vitamin D that is the underlying reason why so many of us contract virus infections during the winter period.

For the first time in history, Danish researchers have revealed that the white blood cells designed to combat virus and bacteria cannot function without the presence of vitamin D. According to Professor Carsten Geisler from The Faculty of Health and Medical Sciences at University of Copenhagen, the so-called T-killer cells depend every bit as much on vitamin D as a car needs a battery to start. As soon as the white blood cells recognize a harmful micro-organism they start to multiply at an explosive rate and attack the enemy like an aggressive and targeted army, provided that there is enough vitamin D.

Controlled by vitamin D, the immune cells release a peptide with an antibiotic effect on numerous microbes, including bacteria such as M. tuberculosis that causes tuberculosis in humans.

Lack of vitamin D increases the risk of virus infections

Even if you feel in great shape, your immune defense may be compromised to a lesser or greater extent if you lack vitamin D. According to American research, the risk of catching a cold or the flu is increased by a whopping 40% when your vitamin D levels are low. People who suffer from asthma or airway diseases to begin with are five times more likely to catch the flu if they are vitamin D-deficient, compared with those who have higher levels of the nutrient in their bodies.

Virus infection often leads to complications

Under normal circumstances, a human should be able to fight a virus infection within a week. With a reduced immune defense, however, there is a risk of complications such as bronchitis, sinus infection, middle ear infection, and pneumonia. The complications arise as a consequence of the virus infection literally seizing the exhausted immune defense whereby bacteria from the natural microflora of the pulmonary system are able to spread to parts of the body where they normally don't belong. That way virus infections can turn into serious conditions, especially among the elderly and week who often die of pneumonia.

We can only synthesize vitamin D during summer

The major part of our vitamin D is synthesized when circulating cholesterol in our skin reacts with sunlight. However, in our part of the world we are only able to produce vitamin D during the summer period when the sun is high in the sky. Vitamin D is stored in the liver and many people become deficient when their vitamin D reserves are used. It is therefore no coincidence that virus infections such as colds and the flu typically spread during the wintertime.

It is a common misconception

- that we humans can produce vitamin D in the wintertime, as long as we expose ourselves to sunlight. This is a myth - the sun is too low in the sky.

Researchers claim that the RDA level for vitamin D is too low

When we sunbathe and our entire body gets exposed to UV-light, it is possible to produce more than 100 micrograms of vitamin D in the skin in just half an hour. 10 minutes of sun exposure to the face and hands, on the other hand, can only produce 30 micrograms in the same period of time. In comparison, a normal vitamin pill contains 5 micrograms of vitamin D (the recommended RDA level in some countries), while the RDA level for children is 10 micrograms.
Several scientists argue that the body's actual vitamin D requirement is substantially higher than the RDA level and recommend a daily allowance in the range between 30-100 micrograms.

Vitamin D, supplements, and absorption

Vitamin D is a lipid-soluble vitamin for which reason the best absorption is obtained with supplements that contain the nutrient dissolved in capsules with some kind of oil. It is safe to ingest high-dosed supplements with 38 micrograms of vitamin D 1-2 times daily.

The body's vitamin D status can be determined with a blood test

Vitamin D deficiencies are common

An estimated 50% or so of Scandinavians are believed to lack vitamin D. Even if a blood test shows an adequate status here and now, levels may drop later in the season and that could even result in a bad autumn cold.
A Danish family practitioner named Doctor Ege Schultz has conducted a study of this patients in which he found that 80% of them were vitamin D-deficient.

Vitamin D deficiency and poor utilization may be caused by

  • Lack of sun exposure during the summer
  • Hyped-up fear of the sun
  • Veils and dark skin
  • Low-fat diet - especially if it does not contain fish and egg
  • Vegetarian and vegan diets
  • Too much calcium from dairy products and supplements
  • Alcoholism
  • Overweight
  • Old age and thin skin
  • Sunscreen with sun factor above 8 (blocks the vitamin D synthesis in skin)
  • Prolonged use of cholesterol-lowering medicine and certain other medical drugs

Vitamin D and tuberculosis

In old days doctors had no clue why it helped to place bed-ridden tuberculosis patients outside in the sun in front of the sanatoriums. Today we know that it was the increased synthesis of vitamin D that often helped them recover.

Did you know that too much calcium inhibits vitamin D?

This is because vitamin D helps regulate the calcium content in the blood, which must always be constant and held within a narrow range. Elevated calcium levels in the blood require too much vitamin D for this regulation function, leaving too little of the nutrient for the immune defense and other vital vitamin D-dependent functions.

Flu vaccine or vitamin D supplement?

71 people must be vaccinated in order to prevent a single case of the flu, according to The Cochrane Collaboration that has looked at 90 studies. The conclusion is that normal healthy adults are in no need of flu vaccine which, by the way, is also associated with side effects. Also, is appears that high-dosed supplements with vitamin D are more effective and completely without side effects.

Always remember good hygiene - especially frequent hand washing


Marina Rode vin Essen, Martin Kongsbak, Peter Scherling, Claus Olgaard, Niels Ødum og Carsten Geisler. Vitamin D controls T cell antigen receptor signaling and activation of human T cells. Nature Immunology

Lasse Foghsgaard: D-vitamin er immunforsvarets batteri.

Gombart AF. The vitamin D-antimicrobial peptide pathway and its role in protection against infection. Future Microbiol

Ane Bodil Søgaard, Karen Østergaard, Troels V Østergaard. Hvad er det du drikker?

  • Created on .