Nearly all of us suffer from colds or flu at some time or other, with the majority getting between 2-6 episodes per year. What are the best ways to both prevent and reduce the duration of these repiratory illnesses? It is often supposed that there is no cure to the common cold and that little can be done other than sit it out. This is not the end of the story however. There are a number of approaches and treatments that show promise in both preventing, and shortening the duration of colds. It is certainly worth giving some of them a try.
The promise of zinc.
Zinc is a mineral that is required for many functions in the human body. It is known that it protects cell membranes against oxidative damage. It also helps our immune system work properly by boosting the amount of infection fighting white blood cells we have1. These properties alone are enough to give it potential to treat colds and influenza. However given the many roles it seems to play in the body, these properties are unlikely to be the only ones that contribute to zinc's efficacy as a cold remedy.
Zinc has been tested against the common cold in quite a few studies. Most use zinc lozenges and some impressive results have been obtained. One used 13.3mg of zinc as zinc acetate, taken every 2-3 hours, amounting to about 100mg per day2. This had the effect of halving the duration of most symptoms and of lessening the severity of symptoms also. Typically this level of supplementation is used for 5 days starting within 24 hours of cold symptoms first appearing. This is an impressive result and not the only one. There are some studies that find fewer benefits from zinc lozenges, but a recent Cochrane review of 15 trials concluded that the evidence was in favour of zinc being an effective treatment3. My take is that it is definitely worth giving this supplement a go if you suffer badly with colds.
How much should I take and where can I get it?
The recommended daily allowance is 15mg. For most people it is safe to have up to 40mg daily for an extended period, however above this level there is a danger of suffering from copper deficiency. That is why the use of zinc against the cold or flu is best done for not for longer than 7 days. The amounts used in the successful studies should not cause serious problems. There may be some gastrointestinal distress, such as nausea or diarrhoea though. Take it in lozenge form, as this delivers zinc to the surfaces of the nose and throat where it can act directly against the cold viruses. Don't bother taking intra-nasal zinc, as this is associated with a permanent loss of the sense of smell.
If you want to give it a try there are some available from http://www.hollandandbarrett.com that contain 7mg of zinc and 300mg of vitamin C. The idea with taking the lozenge every 2-3 hours is to subject the surfaces of the nose and throat to zinc continuously. I would suggest taking the above supplement every 2 hours while awake for 5 days. This would deliver a daily dose of 56mg of zinc and 2.4g of vitamin C. The amount of vitamin C is safe, but could possibly lead to mild diarrhoea. With supplements it is always best to check their ingredients. Many contain additives that you may wish to avoid such as the sweetener, aspartame or for those who suffer from allergy there may be ingredients that exacerbate this.
Vitamin C - does it really work?
Vitamin C has been considered as a cold remedy for a very long time. Like zinc it has a number of effects in the human body including building healthy bone, ligament and tendons, supporting the function of the brain and acting as an all round antioxidant4. It has also been found to stimulate several elements of the immune system4. Evidence that it is a useful tool against colds and flu is mixed.
Reducing the incidence of colds and flu.
When amounts above 0.2g per day were taken, there appeared to be no reduction in the number of colds caught in a number of studies5. However, the number of colds caught by people engaged in strenuous exercise or under cold conditions was halved in 6 studies on these particular subgroups6. The same studies also indicated a greater effect in children. It is thought that this could be indicative that greater amounts of vitamin C should have been used in the studies, as children being smaller require less vitamin C.
Having read through some of these studies my general advice would be to keep up your vitamin C levels by eating plenty of fruit and veg, such as peppers, berries and citrus fruit. If you going to perform arduous physical activity or are entering a colder climate, especially if you are unused to it, then supplemental vitamin C at doses of about 500-2000mg daily, are likely to be effective. You should dose up before you engage in the activity or change location, and for 1-2 weeks afterwards. Splitting the dosage up over the course of the day should help.
Reducing the duration and severity of colds and flu.
Most studies have shown a small reduction in symptoms and duration of colds and flu when using supplemental vitamin C at doses above 200mg. There is still however, plenty of debate about how much should be used for it to be effective. Proponents of orthomolecular medicine claim amounts ranging from 2-18 or more grams per day should be used. I would advise that it may be worth a try. It is most likely to be effective if you are already deficient in vitamin C. This is most likely if you eat few fruit and vegetables or have been ill recently.
What about Echinacea?
Echinacea is a popular cold remedy. It has been shown to activate certain elements of our immune systems, in particular Natural Killer cells and interferon proteins that could act against cold and flu viruses. However, the echinacea used to treat or prevent colds and flu varies for three reasons
- There are 3 different species used to make echinacea supplements. Augustifolia, pallida and purpurea.
- There are different parts of the plant that may be used to create a supplement.
- There are different ways of extracting the active ingredients from the plant.
That said, studies of the effects of echinacea are generally positive. They indicate that the most effective species is echinacea purpurea and that the aerial parts of this plant are the most effective. An analysis of 16 trials by the Cochrane review, indicated that echinacea is not effective at preventing colds, but suggested that a reduction in the duration of colds by 1/3 is possible7. However another analysis of 14 trials by the University of Connecticut concluded that the risk of catching colds could be reduced 58%, and the duration of the colds could be reduced by 1 1/2 days. The fact that most echinacea supplements are different, makes drawing conclusions from these studies somewhat difficult.
Some health authorities advise that echinacea should not be taken for an extended period. As such my advice for those trying out echinacea would be to stick to the echinacea purpurea extracts that use aerial parts of the plant. Take some either at the first signs of a cold for a maximum of 3 weeks, or to prevent a cold, consider taking it for 3 weeks when you feel there is an increased chance you may catch a cold. Possible times of increased cold risk include flying abroad, travelling on other forms of public transport in winter or dealing with large numbers of children after a break. e.g. a schoolteacher after the summer holidays.
Other possible approaches
I've run out of space to cover everything, but it is worth considering the following:
Exercise is associated with a reduced risk of colds and flu. If you are feeling refreshed and energised by your exercise it will increase your chances of fending off any bugs. If you are tired, it may not.
Beta Glucan is a sugar like substance found in brewers/bakers yeast. Some studies show this to be very effective. I plan to investigate this in a forthcoming article.
Vitamin D deficiency, which is common in winter can increase our risk of catching colds and flu.
The black elderberry extract also has some positive trials suggesting it could be helpful.
Summary about supplements.
Do bear in mind that all of us are different, and that if one supplement seems to be working for for somebody you know it won't always work for you. With all supplements, firstly make sure they are safe and won't react with any medications you are taking. It is then OK to try them out. If you appear to be benefiting after a few goes then it may well be worth continuing with it. Make sure you get a good quality supplement, and that the amount you are taking of the active substance is sufficient to have the desired effect.