Cold season is upon us and many people are becoming infected with the common cold and other upper respiratory tract infections. Some believe that catching a cold is inevitable and down to bad luck of being around infected individuals. This is based on the pathogen theory of infection that suggests that once the pathogen is present in a host infection becomes inevitable. However, it is clear from anecdotal evidence that some people just don’t get colds. While it is just as likely that we all have equal exposure to infection, observation shows that some people and some sub-groups are more prone to infection that others. While genetic factor undoubtedly play a role in this resistance to infectious agents, increasingly the nutritional quality of the diet is being shown to play by far the biggest part in preventing the development of infection. In this regard maintaining an optimal functioning immune system that can resist infection is dependent on a high quality diet containing a range of immune boosting essential and nonessential nutrients.
It was Claude Bernard who popularised the idea that the host health played the largest part in the susceptibility to infection when he coined the term the milieu interieur or internal environment. What he meant by this was that it was not the pathogen that dictated the susceptibility to infection but host defences. A healthy host with a good immune system can interact with a pathogen and not become infected because the immune system defences are able to destroy it before an infection is initiated. Increasingly this is being found to be true and the nutritional literature is replete with studies showing immune boosting effects for particular nutrients. One paper published in the Canadian Medical Association1 Journal investigated some of the common nutrients and techniques that are able to reduce the susceptibility to and duration of the common cold. These nutrients and techniques alter the host terrain to make it problematic for the colonisation of infective agents.
The authors most interesting finding was that the best way to prevent a cold is to avoid contact with the pathogen. This is unsurprising as no infection can begin without an infective agent. Handwashing and hand disinfection for example was found to be highly effective at preventing colds because it removed the presence of pathogens from the hands which could be wiped onto the face to enter to soft tissues of the eyes, mouth and nose. Another technique that was highly effective was gargling with water. In this regard, gargling a water solution can reduce the risk of upper respiratory tract infections by around 40 %2. This is a common practice in Japan, where it is believed that the gargling washes the throat and maintains the cleanliness of the soft tissues. However, gargling with a povidone-iodine solution, a known wound healing antiseptic did not decrease the rate of infection. Therefore the Japanese belief that the water acts to clean the throat may be correct. The ability of a salt water gargle to prevent infection is also a possibility.
The researchers also analysed studies looking at a number of foods and nutrients to assess their effectiveness at preventing upper respiratory tract infections. Supplementation with zinc showed the greatest promise in this regard with zinc supplements significantly reducing the number of colds developed over the winter period. Zinc is a nutrient known to be required for effective immune function. Probiotic supplementation also proved effective at reducing upper respiratory tract infection rates, and this likely relates to the ability of the bacteria present in the probiotics to inhibit the growth of pathogenic strains. Vitamin C is also required for correct function of white blood cells, and it is therefore unsurprising that it was shown to reduce the duration of colds and to prevent colds in people under physical stress. Another interesting finding was that honey was shown to have benefits in cold prevention. This may relate to the complex mixture of phytonutrients that are diligently collected by the bees from a range of botanical sources.
Dr Robert Barrington’s Nutritional Recommendation: A high quality diet goes a long way to preventing the common cold. In contrast stress can seriously damage host immunity and increase the susceptibility to infection. Reducing stress during the cold season and making sure a high quality diet is consumed is therefore the best strategy to prevent colds. As intense exercise is a form of stress, extra care must be taken by athletes and those with rigorous physical exercise regimens.
RdB
