Summer’s gone and cold and flu season is here, so you may want to make sure your vitamin D supply is up to par. Here’s why: the common cold is the top reason for doctor visits in the United States and is the most cited reason for work and school absences, including 189 million lost school days each year. In fact, there are a whopping one billion colds per year in our nation. Likewise, influenza, or the flu, accounts for 25 million doctor visits annually, and results in 100,000 hospitalizations and 36,000 deaths annually.
The symptoms the common cold and the flu are often similar, since both are caused by the same family of respiratory viruses. According to John Hibbs, N.D., of Seattle, Washington, “the distinction between the two depends on how severe the infection is and the range of symptoms. The flu is usually more severe, develops quickly and involves more of the body than a cold. A cold also occurs at any time of year, while the flu usually develops in more widespread outbreaks, normally in late fall and winter. Beyond respiratory inflammation, the flu produces a moderate-to-high fever, aching muscles, acute fatigue and may lead to pneumonia in particularly susceptible individuals.”
Colds can happen at any time, but occur more frequently during fall and winter months. Beginning in late August or early September, the incidence of colds increases and remains high until March or April. During cold weather months, people spend more time indoors, which increases chances of viruses spreading from person to person. In addition, the colder seasons bring about lower relative humidity, an environment in which the most common cold-causing viruses can better survive—with some viruses able to live from 20 minutes to two hours or longer on surfaces like desks, doorknobs, keyboards, smart phones and more. Both the cold and the flu are viral upper respiratory infections. There are over 200 different viruses known to be responsible for the common cold, whereas there are two main types of the influenza virus.
Now, back to vitamin D . . . as you may realize, vitamin D is known for numerous health benefits, but having enough vitamin D may also mean that you have fewer colds and flu. One of the largest studies to date on vitamin D indicates that those who have the lowest vitamin D levels also have significantly more cases of cold and flu than those who have higher levels of vitamin D. Why? Simply put, vitamin D plays a critical role in immune system function. The study, published in the Archives of Internal Medicine, followed nearly 19,000 adults for six years and found that those with the lowest vitamin D levels (less than 10 nonograms per milliliter of blood) were 36 percent more likely to report having a recent upper respiratory tract infection than those with higher levels of vitamin D (30ng/mL or higher).
Study researcher, Adit Ginde, M.D. of the University of Colorado, Denver, Division of Emergency Medicine, says, “The findings of our study support an important role for vitamin D in prevention of common respiratory infections, such as colds and the flu. Individuals with common lung diseases, such as asthma or emphysema, may be particularly susceptible to respiratory infections from vitamin D deficiency.”
Interestingly, UCLA scientists discovered that vitamin D also functions to increase the body’s production of a class of proteins called antimicrobial peptides. These peptides can quickly and directly destroy cell walls of viruses. They also play a role in preventing the immune system from releasing too many inflammatory cells, called chemokines and cytokines, into lung tissue—which can sometimes cause drastic and deadly respiratory tract damage. In fact, during autopsies after the 1918 flu pandemic, medical scientists found destroyed respiratory tracts as a result of these inflammatory cytokines’ disastrous effects on the epithelial cells lining the respiratory tract. Fortunately, this type of severe inflammatory reaction is now thought to be prevented by adequate vitamin D intake.
This cold and flu season, don’t take any chances. Be sure your vitamin D levels are where they need to be.