Researchers at Appalachian State University in North Carolina suggest engaging in regular physical activity or exercise may boost a person's immunity against upper respiratory tract infection (URTI) or common cold.

David C Nieman and colleagues reported in the Nov 1, 2010 issue of the British Journal of Sports Medicine found subjects who reported five or more days per week of aerobic exercise had the duration of common cold they suffered reduced by 43 percent, compared with those who were sedentary.

Previous studies suggest an inverse association between physical activity or fitness level and incidence of common cold. The current study was meant to see if physical activity reduces symptoms and severity in adults.

Participating in the study were 1002 men and women aged 18 to 85 years, who were followed for 12 weeks during the winter and fall seasons in 2008 for common cold symptoms, severity an duration in the participants.

Participants were told to report frequency of aerobic activity and rated their physical fitness level on a 10-point scale.

Those who gave their physical fitness a high score experienced 46 percent fewer days with upper respiratory tract infection, compared to those who gave themselves a low score.

The researchers concluded "Perceived physical fitness and frequency of aerobic exercise are important correlates of reduced days with URTI and severity of symptoms during the winter and fall common cold seasons."

The authors of the study said physical exercise sparks a temporary rise in immune system cells circulating around the body.

Common cold results in a loss of 22 million school days, according to the Centers for Disease Control and Prevention. 

Common cold hits children and young adults more often.  Children have about 6 to 10 colds a year while adults have 2 to 4 colds a year.  People older than 60 have fewer than one cold a year.

Studies have proved that physical activity like walking  and cycling can boost a person's immune function.

Monika Fleshner and colleagues at the University of Colorado-Boulder inoculated a benign T cell-dependent protein isolate in study subjects and then three weeks later, they tested subjects and found physically active older people had significantly higher antigens including IgM, IgG, IgG1 ad DTH, compared with the sedentary older people.

The study was reported in the Aug 2004 issue of the Journal of Applied Physiology.

The current study found study participants experienced cold symptoms for an average of 13 days in the winter, compared to eight days in the fall.

Could this also suggest vitamin D partially accounts for the protective effect against common cold?  People often have lower levels of vitamin D in the winter and physically active people may be more health conscious and get more sun exposure or even taking some sort of vitamin supplement than their counterparts.

Studies have already linked high levels of vitamin D with reduced risk of acquiring common cold.

One study in the June 14 2010 issue of PLoS One suggests taking vitamin D supplements may cut the risk of common cold.

Sabetta J.R and colleagues, authors of the study, at Yale University School of Medicine in New heaven, Connecticut said in their report that declining serum levels of 25-hydroxyvitamin D see in the fall and winter may be a risk factor in the seasonal increased incidence of flu and other viral infections.

Their study was meant to examine the association between serum 25-hydroxyvitamin D concentrations and incidence of acute viral respiratory tract infections.

For the study, they measured concentrations of 25-hydroxyvitamin D in 198 healthy adults monthly over the fall and winter in 2009 to 2010 and evaluated the participants for the development of any acute respiratory tract infections. 

Participants with 38 ng/ml or higher of hydroxyvitamin D in their blood had a significant two-fold reduction in the risk of developing acute respiratory tract infections.

Studies have proved vitamin D boosts innate immunity by helping produce peptides against viruses and bacteria.

A Japanese trial study has even demonstrated school children taking 2000 IU of vitamin D for a year helped protect against influenza with its efficacy better than flu vaccine.

So overall evidence suggests that taking vitamin D may reduce risk of common cold.

Jimmy Downs