Vitamin D crucial to activating immune defences
Anthony Marrelli
Argus
The human immune system is a mysterious and important focus in medical science. When death occurs, the immune system along with everything else shuts down. In a matter of hours, the body is invaded by all sorts of germs that normally have little effect when the immune system is working properly.
In just a short time these organisms completely dismantle the body and eat away at it until nothing remains. The immune system is doing something amazing to keep all of that dismantling from happening when a person is alive.
Scientists at the University of Copenhagen have discovered that Vitamin D is crucial to activating the human immune defences and that without sufficient intake of the vitamin, the killer cells of the immune system, T cells, will not be able to react to and fight off serious infections in the body.
For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses, the cells must first be triggered into action and transform from inactive and harmless immune cells into killer cells that are primed to seek out and destroy all traces of a foreign pathogen.
The researchers found that the T cells rely on vitamin D in order to activate and they would remain dormant, naive to the possibility of threat if vitamin D is lacking in the blood.
In order for the specialized immune cells (T cells) to protect the body from dangerous viruses or bacteria, the T cells must first be exposed to traces of the foreign pathogen.
This occurs when they are presented by other immune cells in the body, known as macrophages, with suspicious cell fragments or traces of the pathogen.
The T cells then bind to the fragment and divide and multiply into hundreds of identical cells that are all focused on the same pathogen type.
The sequence of chemical changes that the T cells undergo enables them to both be sensitized to and able to deliver a targeted immune response.
Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology explains that “when a T cell is exposed to a foreign pathogen, it extends a signalling device or antenna known as a vitamin D receptor, with which it searches for vitamin D.
This means that the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won’t even begin to mobilize.”
T cells that are successfully activated transform into one of two types of immune cell. They either become killer cells that will attack and destroy all cells carrying traces of a foreign pathogen or they become helper cells that assist the immune system in acquiring a metaphorical memory.
The helper cells send messages to the immune system, passing on knowledge about the pathogen so that the immune system can recognize and remember it at their next encounter.
T cells form part of the adaptive immune system, which means that they function by teaching the immune system to recognize and adapt to constantly changing threats.
Vitamin D is important for calcium absorption and the vitamin has also been implicated in diseases such as cancer and multiple sclerosis, and now it is known to be crucial to activating the immune system.
Most Vitamin D is produced as a natural by-product of the skin’s exposure to sunlight. It can also be found in fish liver oil, eggs and fatty fish such as salmon, herring and mackerel or taken as a dietary supplement.
No definitive studies have been carried out for the optimal daily dosage of vitamin D but as a large proportion of the population have very low concentrations of vitamin D in the blood, a number of experts recommend between 25-50 micrograms per day.