Coming up over the next few months: around 120 million episodes of cold and flu. Make sure your name isn't on the packet of Kleenex by acquiring a detailed understanding of how these unpleasant viruses are transmitted. Recent research provides some useful clues.
WASH YOUR HANDS
Touching everyday objects with contaminated hands is the number one cause of harbouring, spreading and acquiring the common cold virus. Our behaviour makes this easy: unobserved, a person will put their finger in their nose on average once every three minutes, according to research carried out by the National Heart and Lung Institute at Imperial College, London. And being extra hygienic when a cold sufferer is in the vicinity won't necessarily help matters.
The common cold virus has a far greater longevity than previously realised, according to new research from the University of Virginia. One in two healthy people developed a cold after staying in a hotel room that had been occupied by a cold sufferer within the previous four days. Most commonly infected surfaces were light switches, pens, telephones, handles, taps and television controls.
Staying at home is at least as dangerous, especially one shared with infants or children. "Young children are prone to colds because their immune systems are learning to cope with them. Also their personal hygiene is not good, their noses are running and mucus gets everywhere," says Dr Ron Eccles of the Common Cold Centre in Cardiff.
What to do
Wash your hands properly at least five times a day, including after each episode of coughing, sneezing or nose-blowing. A quick swill under the cold tap is no help whatsoever. A proper hand wash has five distinct steps:
* Wet hands with warm running water prior to reaching for the soap.
* Rub hands together to make lather. Do this away from running water, so the lather isn't washed away.
* Wash the front and back of your hands, between your fingers and under the nails. Continue washing for 20 seconds or more.
* Rinse hands under warm running water.
* Dry hands thoroughly with a clean towel or air dryer.
EAT FOR YOUR IMMUNE SYSTEM
Living in relatively crowded conditions and engaging in conversations and other social activities makes it difficult to avoid completely the 250 different cold viruses. For every person with a streaming nose, another two or three have the virus but don't have any symptoms. Those who succumb have a depressed immune system that increases susceptibility to infection. Three ways to boost your immune system are:
A well-balanced diet with adequate carbohydrate, protein and fat intake is of key importance in the maintenance of the immune system. As the cold months approach, particular nutrients become more important to a normally functioning immune system, says Dr Joanne Lunn of the British Nutrition Foundation. As well as vitamins and minerals contained in fruit and vegetables, these include:
* Iron Rich sources include red meat, fish, liver and pâté. Plant sources include kidney beans, lentils, tofu, apricots, prunes, figs and fortified breakfast cereals. Vitamin C enhances absorption of iron, so eat foods in combination: kidney beans with tomatoes or breakfast cereal with a glass of orange juice.
* Zinc Rich sources include red meat and fish, particularly oysters, and pumpkin and sunflower seeds. Milk and cheese, wholegrain cereals and lentils also contain zinc.
* Selenium Good sources include Brazil and cashew nuts (above), fish and shellfish, especially crab, and mung and soya beans.
TUNE YOUR DIET TO THE SEASONS
Autumn is a "windy" season, according to ayurveda, the ancient Indian system of health. It's a time when vata, a combination of the elements of air and space within the body, is prone to imbalance, and our digestion can become erratic too. "Our diet at this time should be grounding, warming and easy to digest," says Sebastian Pole, an ayurvedic practitioner in Bath. He recommends warm foods such as cooked grains, especially rice and oats, plenty of fruit and vegetables rich in vitamin C and root vegetables such as sweet potato, soups and foods that are easy to digest.
Couch potatoes have a greater chance of getting a cold or flu than the moderately active, according to research from Loughborough University. "Moderate exercise boosts white blood cells as well as increasing the concentration of antibodies in the saliva, protecting against respiratory infections," says Mike Gleeson, professor of sport science and co-author of Immune Function in Sport and Exercise (Churchill Livingston, 2006).
Recreational activity such as gentle walking, however, is healthier in winter than doing a marathon, according to sports scientist Dr Greg Whyte. "The harder-training athlete is at greater risk of contracting a winter illness compared with the general population, with an open window to infection in the hours that follow a prolonged workout," he says.
It's worth avoiding physiological and psychological stress during the time of year when colds and flu are most virulent - as well as ensuring that you are not overtired after training.
Mainstream dietary experts are adamant that swallowing pills cannot reduce your risk of getting an infection. "Getting nutrients from food is far more beneficial than taking the same nutrients in tablet form," says Dr Lunn of the BNF. However, an extremely healthy vitamin and mineral industry, and several million supplement devotees, beg to differ. Here are the best of the bunch:
* Echinacea There are conflicting views on the benefits of echinacea, the top-selling herb for prevention of colds in the US and Europe. Evidence for efficacy supports only fresh extracts of Echinacea purpurea, preferably in tincture form, making the herb more bio-available. The best-selling product, Echinaforce, has all these qualities as well as a strong evidence base. New research showing how and why we suffer cold and flu symptoms has also thrown light on the benefit of herbs such as echinacea, which modulate rather than boost the immune system.
The cold virus does not invade the whole body and then cause various unpleasant symptoms: it takes hold in the lining of the nose and upper part of the respiratory tract, staying there to reproduce. "It is the reproduction of the virus and your body's immune reaction to it that causes the feelings commonly associated with the common cold," says Dr Whyte.
The Centre for Pharmaceutical Research in Zurich says that because echinacea calms the immune system, it prevents this immune reaction, and thereby keeps symptoms at bay.
* Ginseng Taking 200mg capsules of North American ginseng root cuts the risk of colds by more than 30 per cent.
* Garlic A 12-week placebo-controlled trial, comparing garlic extract with placebo found that those taking garlic were two to three times less likely to develop a cold or flu.
* Yoghurt A daily dose of probiotics such as acidophilus or lactobacillus has been shown to prevent colds and flu and digestive problems. "It makes sense," says Tom MacDonald, professor of immunology at Barts and the London School of Medicine. "The gut contains most of the immune cells in the body, so drinking probiotics gives the immune system a boost to prevent infections."
* Vitamin C Research suggests that taking the recommended daily dose of 60mg of vitamin C reduces the risk of colds by a mere 4 per cent. However, followers of the double Nobel Prize-winner Linus Pauling argue that size matters. A major review of 60 studies, published in the American Journal of Epidemiology in 2000, for instance, reported that taking 1,000mg of vitamin C every day reduces symptoms of colds.
MORE WAYS TO STAY COLD-FREE
* Keep warm A drop in body temperature can dampen the immune system and allow the bug to take hold. In very cold weather, it's sensible to wear a scarf over your nose, the first line of defence in the immune system. The cilia in the nostrils that brush away bacteria and viruses slow down when chilly.
* Be happy A cold virus was squirted up the noses of human guinea pigs who were then asked to fill in a happiness questionnaire at Carnegie Mellon University in Pennsylvania. Happy people were found to be three times less likely to develop a cold.
* Have sex (but don't overdo it) People who have sex once or twice a week have stronger immune systems and fewer bouts of colds and flu, according to research at the University of California at San Francisco. This may be because they are exposed to a wider range of infectious agents than those non-sexually active. However, those who report three or more weekly sexual encounters have weaker immune systems. Immunologists say the very frequent sex group may be more anxious and stressed as a result of being obsessive or in a poor relationship.
* Use drugs Vicks First Defence spray traps the virus in a gel, preventing it from penetrating the back of the nose. Trials have shown that if taken within two days of the appearance of symptoms, enough of the virus is prevented from entering the body to reduce the severity and length of the infection.
Prescription antiviral drugs such as Tamiflu and Relenza can stop the virus replicating, must be taken early. The flu jab is safe and effective and available free for people at greatest risk of harm from influenza.
COLDS AND FLU - WHAT IS THE DIFFERENCE?
* Colds are caused by hundreds of different types of virus. This is why most of us get around six colds a year. You can catch a cold at any time of the year. While the common cold targets the nose and the upper part of the respiratory tract, the flu virus infects the whole of the respiratory symptom, making the risk of associated complications, such as bacterial pneumonia, much greater - and thus making a more worrying condition.
Cold symptoms are confined above the neck and rarely cause a fever.
* Flu is caused by the much more serious influenza virus, and new strains appear each year. There are three major types: A (often the cause of flu epidemics), B and C. You're unlikely to catch flu in the UK outside November to February. Symptoms come on suddenly and include headache, fever, muscular and joint pain and bodily weakness as well as sensitivity to light, nausea and vomiting.