The advice to ?feed a cold, starve a fever? may be right after all, researchers have discovered. Until now, most doctors and nutritionists have rejected it as myth. But Dutch scientists have found that eating a meal boosts the type of immune response that destroys the viruses responsible for colds, while fasting stimulates the response that destroys the bacterial infections responsible for most fevers.
?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.
At a Christmas dinner, he 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. So the team got six people to fast overnight and then come into the lab for tests. On one occasion they were given a liquid meal, on the other just water.
Six hours after the liquid meal, the volunteers? levels of gamma interferon had more than quadrupled. Gamma interferon indicates a cell-mediated immune response, in which killer T cells destroy any cells that have been invaded by pathogens. ?This type of immunity is mainly directed against viral infections,? says van den Brink. ?It seems to be stimulated by food.?
When the volunteers drank only water, levels of gamma interferon fell slightly, while levels of another chemical messenger, interleukin-4, nearly quadrupled. Interleukin-4 is involved in the humoral immune response, in which B cells produce antibodies that attack pathogens lurking outside our cells. This response is needed to kill off most bacterial infections. ?It fits exactly with what we recently found,? says Paul van Leeuwen of the Free University Hospital, also in Amsterdam. His team has discovered that glutamine, an amino acid common in milk, meat and some nuts, boosts the cell-mediated immune response.
Van den Brink speculates that the immune response following eating evolved as way of saving energy. Whereas most bacterial infections need an immediate response, fighting off a virus to which we have already been exposed can wait until we have more energy.He says, ?Certain foods could be given to critically ill patients to stimulate the right immune response.?
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