by DAVE MIHALOVIC
“Dress warm or you’ll catch a cold” said every parent that ever existed. While it’s partially true that the body’s optimal temperature is a significant player in a well-functioning immune system, that’s only part of the equation. The other two reasons we get sick are far more relevant as to why millions are more vulnerable to cold viruses in colder climates.
There are three major mechanisms that allow cold viruses to infiltrate our immune systems in the winter:
1) Adapting To Colder Temperatures Affects The Immune System
The least important factor, although still significant in effectively battling and surviving cold is the body’s ability to maintain its internal core temperature around 98.6F (37C) degrees.
The reason our parents have always insisted we stay warm to prevent colds is not an old wives tale at all. Our physiological systems which adapt to cold and wet environments causes the most heat to escape the body and makes it more difficult for the body to replace lost heat. This directly depresses our immune system in the process.
The body will inherently expend its resources differently in order to keep itself warm. During this process, the body will modify physiological mechanisms and reallocate the amount of carbohydrates used. Accordingly, the body is more responsive to glucose in the winter and consumption of foods high in sucrose can further depress this delicate system.
Many of these physiological systems slow down as the body attempts to balance the internal body temperature to external stimuli. As temperatures get colder, the nervous system will slow down and the impulses that move our muscles and blood flow will also be affected.
Simultaneously, the body will use more carbohydrates to produce lactic acid. This lactic acid combined with the deceleration of the nervous system will also force the body to slow down, so that it can retain heat. As cold increases, blood vessels constrict and causes blood flow resistance to increase.
The more heat the body can conserve, the more successful the body is at keeping its core temperature in a healthy range.
2) Lack of Vitamin D
The second most important factor in the battle of cold viruses in colder climates is the direct correlation to lower levels of Vitamin D.
When vitamin D binds to specific receptors, it sets off a chain of events by which many toxic pathogens and agents including cancer cells are rendered harmless. However, if there is not enough vitamin D the system can become overwhelmed and cancer can develop. It’s one of the reasons that people living closest to the equator have a much lower incidence (or absence) of the common cold and disease in general which generally increase in locations further from the equator.
Although vitamin D can be obtained from limited dietary sources, it is the directly exposure from the sun during the spring and summer months where we get the highest amounts of absorbable levels of the sunshine vitamin. Just 30 minutes exposing your torso to the sun in warmer months is equivalent to roughly 10,000 units (UI) of vitamin D.
Under the right circumstances, 10 to 15 minutes of sun on the arms and legs a few times a week can generate nearly all the vitamin D we need. Unfortunately, the “right circumstances” are elusive: the season, the time of day, where you live, cloud cover, and even pollution affect the amount of UVB that reaches your skin.
What’s more, your skin’s production of vitamin D is influenced by age (people ages 65 and over generate only one-fourth as much as people in their 20s do).
It is known that vitamin D has a wide range of physiological effects and that correlations exist between insufficient amounts of vitamin D and an increased incidence of colds, flu and disease in general. The combination of poor dietary intake and sun avoidance has created vitamin D deficiency or insufficiency in large proportions of many populations worldwide which leaves them directly vulnerable to the common cold and flu virus.
3) Cold and Flu Viruses Love The Cold
There is a difference between symptoms related to the cold virus and flu virus, but possibly the number one reason the human body is susceptible to the cold virus in the winter is its virulence. The dry, cold conditions pull moisture out of droplets released by coughs and sneezes, which allows the virus to linger in the air.
Additionally, cold, low humidity air dries out the nasal passages and makes virus transmission more likely. Researchers have found that in winter, even the flu virus wears a coat, and it’s a coat that helps the virus spread through the air.
“Like an M&M in your mouth, the protective covering melts when it enters the respiratory tract,” Joshua Zimmerberg, PhD, chief of the cellular and molecular biophysics lab at the National Institute of Child Health and Human Development (NICHD) says in a news release. “It’s only in this liquid phase that the virus is capable of entering a cell to infect it.”
In warmer temperatures, that coating doesn’t form. So it’s harder for the influenza virus to spread through warm air.
Virologist doctor Peter Palese has been studying the effects of heat and cold on the flu virus. He found that at higher temperatures, the flu virus didn’t spread.
There is no question that the cold virus is more stable in cold temperature, so it survives and lingers airborne much longer.
When we cough or sneeze, microscopic droplets of water and the virus enter the air. Dry, cold conditions dry out the droplets, helping the virus linger in the air. The dry air also dries out nasal passages, which helps the virus stick. Cold dry air going over our nasal mucosa gets cracks in our airways which allows a virus to get in more easily and challenge the immune system.
Read Part 2: 6 Ways To Keep Your Immune System Strong Against The Cold Virus