Trust in the Old Wives    The old wives�?tale, "feed a cold and starve a fever", has long been dismissed as bunkum by doctors. But new research in the Netherlands suggests that feeding and fasting have dramatically different effects on the immune system. And whoever the old wives were, they may well have been right. Dutch scientists have found that eating a meal boosts the immune response that destroys viruses like those causing colds, while fasting stimulates the response that tackles the bacteria to blame for most fevers caused by illnesses such as bronchitis and tonsillitis. "To our knowledge, this is the first time that such a direct effect has been demonstrated," says Gijs van den Brink of the Academic Medical Center in Amsterdam. The research, published in this month’s New Scientist, was prompted by informal observations of the effects of alcohol and food on the scientists themselves. At a Christmas dinner, van den Brink and his colleagues decided to take blood samples to see if alcohol affected the immune system. To their surprise, later analysis suggested that alcohol had no effect, but food did. The next part of the research was more formal. The team asked six volunteers to fast overnight and come into the lab for tests. On one occasion they were given a meal, on the second just water, to distend the stomach. The results were striking. Six hours after the volunteers ate a meal, their levels of gamma interferon had more than quadrupled. Gamma interferon is a hallmark of a specific immune response. "This type of immunity is mainly directed against viral infections," van den Brink says. "It seems to be stimulated by food." Thus the truth of "feed a cold" appears to be borne out. When the volunteers drank only water after a night of fasting, levels of another chemical messenger, interleukin-4, nearly quadrupled. Interleukin-4 is characteristic of the humoral immune response, which is needed to tackle most bacterial infections. So, in the case of bacterial infections that cause a fever, a fast seems to be able to stimulate the appropriate immune response. Thus "starving a fever". Scientists are now trying to discover which foods in particular will help the body fight off colds. Paul van Leeuwen of the Free University Hospital, also in Amsterdam, has discovered that glutamine, an amino acid common in milk, meat and some nuts, is particularly good. Doctors working independently of the Dutch study have discovered that patients in intensive care are less likely to succumb to infections if given glutamine supplements. The Dutch team cautions that the research is at a very early stage and people should not change their behaviour after such a small study. But van den Brink thinks finding out exactly what stimulates the different responses will be useful: "Certain foods could be given to critically ill patients to stimulate the right immune response." Although some foods are known for their ability to improve the general immune system, this research and others like it may result in doctors prescribing certain foods to allay specific conditions. Community GP Dr Richard Edwards believes many of the traditional remedies may well turn out to be true. "If patients come to me asking whether or not an old family cure - Granny’s chicken soup, for example - will help their colds I try not to be sceptical. Of course, a lot of the benefit could be down to believing that it is doing you good and the comfort factor," he says. "However, it wouldn’t surprise me at all if tried-and-tested remedies for colds did turn out to have something in them - look at the age-old advice to ‘eat up your greens�?- perfectly sound medical advice." The next step may well be examining foods traditionally associated with treating the common cold to see if they do have helpful properties. Orange juice, chicken soup and honey and lemon may yet prove to be a bit more than old wives�?cures.   Now take a mustard bath... Naturally beneficial - five traditional remedies found to be effective in medical studies.    1. An apple a day keeps the doctor away Apples are a rich source of a soluble fibre called pectin. French scientists have shown that eating two a day provides enough pectin to reduce cholesterol levels by 10 per cent. Add vitamin C, potassium and folic acid and you have a prescription for good teeth and gums, a healthy heart and a long life.    2. Eating carrots will help you see in the dark This will help if you have a chronic shortage of vitamin A in your body, as this is responsible for good night vision. Any vegetable which is a good source should help. However, if you eat a healthy balanced diet and have no problems with vision, then extra carrots will not give you the natural equivalent of night-vision goggles.    3. Cabbage leaves help breast feeding Wrapping cabbage round your breasts may sound odd but it works. The leaves improve the flow of breast milk and prevent sore nipples. They also relieve the discomfort of mastitis and menstrual breast pain. The anti-inflammatory phytochemicals and sulphur compounds in the leaf are absorbed through the skin. Bruise the leaves first and wear them inside a bra.    4. Eating fish makes you brainy Fish, especially oily fish such as sardines, mackerel, salmon, pilchards and herrings, are good sources of omega-3 fats, which are needed for the development of brain and nerve cells, especially before birth and in the first few years of childhood. So, while fish oils are important for early brain development, eating fish when you’re older doesn’t actually make you more brainy. But research suggests that a regular intake of these omega-3 fats is important for brain function throughout life.    5. Mustard treatments can cure colds, coughs and backache A must for any Victorian heroine with a bad cold. A foot-bath of two tablespoons of mustard in hot water helps combat the symptoms of colds and flu and ease aching limbs. Breathing in the steam from a mustard footbath can relieve an irritating cough. A mustard plaster or poultice, applied to the body, brings rapid relief from lumbago and sciatica.