It is inevitable that even the most ardent follower of good high quality nutrition will eventually surbumb to the effects of infection and develop a common cold. While good nutrition and health can reduce the risk of contracting a cold significantly, there is always an element of luck in being in the wrong place at the wrong time, when contracting a cold. Colds are thought to be spread through contact with infected individuals (although this is controversial), but such contact does not inevitably lead to a cold because it is the status of the immune system that is the ultimate arbiter of disease (as suggested by Claude Bernard’s milieu Interieur). Stress and poor nutrition are the real culprits for the spread of viruses and even if the latter is maintained at high levels, the former is often out of the control of the individual. However, should a cold develop, there are number of things that should be done to firstly limit the severity of the symptoms, and secondly to limit the duration of the infection.
Of the steps that should be taken to limit the metabolic damage caused by a cold, the most important is usually the most overlooked. Our society is obsessed with attending work and in this regard most pharmaceutical products aim to provide energy and symptom relief to allow the individual to attend work and maintain their normal habits. The problem with this is two-fold. Firstly, it prolongs the infection and worsens the symptoms for the infected individual. Secondly, by facilitation the normal habits of the individual, the spread of colds to other people in society is assured. If anyone contracts a cold, they should isolate themselves from others and rest. Washing the hand frequently, maintaining good hygiene and avoiding situations that require contact with objects others will come into contact with is also important. Schools are starting to realise the importance of such steps by asking children not to attend school during illness and for a few days following illness. Workplaces would do well to follow this lead to increase productivity.
The immune system is very energy intensive and requires adequate rest to combat a cold. However, other conditions must be satisfied in order to provide the immune system with the tools it required to fight a cold. In particular, the immune system required adequate liquids to maintain hydration. Dehydrating provides a more hospitable environment in the respiratory tract for viruses, and maintaining hydration therefore impedes their ability to replicate. White cells also function better when optimal hydration levels are maintained because the dilution of other substances within the blood enhances the effects of the white cells. Drinking sugary drinks such as glucose, sucrose, fructose containing beverages, as well as honey sweetened drinks is also detrimental because sugar impeded the ability of the white blood cells to kill microbes and negatively affects the function of the immune system. Water, tea and other non-sugar sweetened beverages are therefore the best drinks to consume.
Vitamin C and zinc have both been shown to benefit people infected with colds. It was Linus Pauling that popularised vitamin C in mega-doses to combat the common cold in his book ‘Vitamin C and the Common Cold’. However it does a disservice to other vitamin C advocating nutritionist, to over-emphasise Pauling’s contribution. Studies that have used high doses of vitamin C, and administered it quickly at the onset of symptoms have shown that in doses of 1000 mg every two hours vitamin C can reduce the duration of the symptoms experienced by one day. Studies that have found no effects and been used as evidence of a lack of efficaciousness for vitamin C have generally used too low a dose of the vitamin. Zinc is also beneficial against the common cold, because zinc possess direct antiviral activity. Zinc lozenges (~20 mg every two hours) reduce the severity of the symptoms experienced by the individual, a fact that has been demonstrated in numerous well designed clinical trials.
Other nutritional factors that can be beneficial during periods of infection include the use of certain herbs as well as high dose vitamin A and D therapy. Both vitamin A and its precursor molecule beta carotene may enhance immune function. Beta carotene is doses of 50,000 to 1000,000 IU and vitamin A in doses of 15,000 to 25,000 seem effective, with vitamin A having direct antiviral effects. This dose of vitamin A should not be taken by anyone who is pregnant or at risk of getting pregnant as vitamin A at high concentrations is teratogenic. If this is the case beta carotene should be used instead. Vitamin D may also be effective at reducing the symptoms and duration of a cold, particularly in those with a deficiency. Up to 10,000 IU during the period of infection should be considered. Of the herbs, echinacea sp. and goldenseal (Hydrastis canadensis) have both been shown to possess significant immune stimulating effects and benefit those with colds and are also worth considering.