Test before saying no

Press, 13 July 1985, Page 14

Test before saying no

FOOD ALERT

JANICE BREMER DIETITIAN

In a land described as “flowing with milk and honey” New Zealand seems to have an “epidemic” of food allergies at the moment. Milk allergy comes up time and again in press reports, some exaggerated, others attempting to give the facts. Any allergy is difficult to diagnose with a high degree of confidence, and symptoms are numerous and often diverse. But milk allergy is the most common food allergy. It is seen most frequently in infants because allergies may become most apparent with repetitious eating of a single food. For infants it is milk, milk, and more milk. Careful diagnosis by a medical doctor is, however, essential. Some “health” magazines that warn us of widespread milk allergy, and recommend all sorts of alternatives, confuse true milk allergy with an intolerance to lactose, the milk sugar. The world “allergy” means an altered or abnormal reaction in certain tissues of our bodies after exposure to a foreign protein, called an “allergen.” Milk allergy is, therefore, usually a reaction to milk protein. Lactose intolerance, on the other hand, is caused by a deficiency of an enzyme called lactase. This enzyme is responsible for the digestion of the milk sugar, before it can be absorbed by our intestines. Common to both of these problems is that there seems to be an inherited tendency towards them. People who have milder symptoms of intolerance, such as increased mucous formation, can simply test this problem themselves. If they don’t feel better without milk, or only using lowfat milk, then milk is not the cause of their problems. Lactose Intolerance Until about 20 years ago lactose intolerance was thought to be rare. But then

studies in the United States revealed that people with dark skins did not seem to tolerate milk as well as those with white skins. Subsequent studies of world populations show that the majority (excluding those of northern European descent, and certain populations in Africa and India) do have lactase deficiency to some degree. It seems that only those peoples who have depended on milk and milk products in their diets actually retain the lactase enzyme into their adult life. However, what is often not appreciated by those prescribing milk-free diets for lactose-intolerant individuals is that usually their enzyme level is only diminished and is not actually absent. Most people can tolerate the amount of lactose in a glass of milk. (In allergies even the most minute quantity of allergen may have effect). So their intolerance is related to the inherited susceptibility, and the quantity of milk consumed in one “dose.” The side effects are the outcome of inhibited digestion of lactose. These effects are abdominal distention, cramps, flatulence, and/or watery stools. These symptoms are the result of fermentation of the undigested milk sugar by bacteria, which produces gases and acids. Less Lactose Several strategies have been conceived to overcome this intolerance so that all people in homogeneous populations can enjoy and derive nutritional benefit from milk.

The lactose content of milk has been reduced by predigestion of the milk, or a technique called ultrafiltration, and fibre components have been added. A group from Central America has recently reported a more natural approach to reduce the symptoms of lactose intolerance and/or allow a greater tolerance. They had their study subjects have milk with solid meals comprising cornflakes, banana, and egg. The results were that fermentation of lactose in the subjects’ intestines was reduced by 50 per cent. The same group of researchers report a further study in which enzymes that could digest the lactose were added to the milk. The results were favourable, although further research is still required on this method. These same enzymes, called beta galactosidases, have been found in yoghurt. This solves a long-term mystery as to why yoghurt seems to be tolerated by lactose - intolerant people, despite its containing as much lactose as milk. A study reported in the “New England Journal of Medicine” late last year found that the amount of lactose left undigested from yoghurt was only half that left from milk. This news is, of course, only of relevance to those who cannot even tolerate a small amount of milk. Some other dairy products, such as cheese, have a low lactose content, and can also often be tolerated by those otherwise intolerant of milk. Gastroenteritis, other stomach or bowel distur-

bances, or surgery may reduce lactase activity in otherwise normal people. For them, yoghurt may be used to compensate for a temporary lactose intolerance, which is restored to normal by the gentle reintroduction of milk. Food Alert • • Infants and children are the main victims of milk allergy. This is a major reason for recommending breastfeeding for as long as possible, all being well for four months, but possibly up to six months. Allergy to mother’s milk is extremely rare, and it contains protective factors. Most infant formulae are based on cow’s milk, which is one of the most common allergens. By delaying the introduction to a potential allergen, the risk of allergy developing is reduced. (Milk-free formulae are available, however, for infants who are not breastfed.) • Adults are the main victims of lactose intolerance, but they can usually manage to digest the equivalent of a glass of milk in any one meal. If they can not, they should try milk as part of the food component of the meal, or try yoghurt. If milk and dairy products are totally excluded from our diets, careful attention to where we get our calcium is necessary. Milk is traditionally the food we use to nurture our young, to feed a fragile digestion, and to calm an angry ulcer. It is wise to be cautious when reading topical stories of allegations against milk. Very few in our community are afflicted with either a milk allergy, or an intolerance to milk.