Hippocrates had already noticed that some people experienced more or less annoying ailments after drinking cow's milk. In fact, there are those who, even among children, cannot safely enjoy a cup of milk because its ingestion causes cramps, stomach ache, diarrhea… Why? Is it lactose or milk protein to blame? And in one case or another, is the solution to eliminate it completely from the diet?
We talk about it with Alessandro , head of Allergy of the Child Jesus of the city, and Elio Novembre, head of the Allergology Unit of the Meyer of the city.
First of all it is good to clarify that milk is not the only food that can cause adverse reactions and that we are talking about adverse reactions to food we must distinguish between allergies and intolerances. The former are mediated by immunological mechanisms, whereas intolerances are not caused by the immune system. Both are non-toxic reactions, unlike for example mushroom poisoning, which is a toxic reaction caused by the presence of toxins, the effects of which vary depending on the amount of mushrooms ingested.
In this article
- What is a food intolerance?
- Lactose intolerance
- Food allergy, what is it?
- Cow's milk alternatives
What is a food intolerance
"We talk about food intolerance, and not allergy, when the hypersensitivity to a food and the reaction are not caused by the immune system" explains Novembre.
There are different types of food intolerances:
- enzymatic: are those determined by the body's inability to metabolize some ingested substances. Examples of enzymatic intolerances are lactose, favism.
- pharmacological: are those that some manifest to certain molecules present in some foods. In some cases, the reaction may be due to some additives added to the food (although it is not yet clear whether in this case it is intolerance or allergy)
- pseudoallergic: they are those that depend on an excessive intake of substances that are tolerated by the body within a certain threshold, in addition they can cause adverse reactions (for example foods rich in histamine, glutamate, sulphites).
The most common enzyme intolerance is lactose intolerance.
Lactose is the sugar contained in milk. Before being absorbed and used as energy by the body, it must be broken down (into glucose and galactose). This operation is performed by an enzyme: the lactase. Inevitably, if not enough lactase is produced, some of the lactose is not broken down and consequently may not be digested. In fact, poor lactase production does not necessarily imply lactose intolerance. After all, it is physiological that after weaning, the production of this enzyme decreases and then drastically reduces between five and ten years, but not everyone exhibits adverse reactions by drinking a cup of milk for breakfast and then, growing up, a cappuccino.Lactose does not trigger allergic reactions, but digestive difficulties due to the lactase deficiency.
"In Del Paese less than 5% of the general population is lactose intolerant" explains the allergist from Meyer. "But babies are very rare, especially infants," he adds.
Those who are intolerant, the more lactose they ingest, the more obvious symptoms they show. In this case we speak of dose-dependent symptoms (on the contrary, in case of allergy even very small quantities of food are enough to trigger the symptoms). Mostly, the symptoms of milk intolerance are limited to the gastrointestinal tract and they are not serious although they can be annoying: flatulence, diarrhea, bloating and abdominal pain, vomiting, blood loss with stool. They appear shortly after milk intake. Even if the malaise, caused by the fermentation of undigested lactose and absorbed by the intestinal microbial flora, can also occur after some time (for example the next day).
The diagnosis of lactose intolerance is made by exclusion. Basically, milk is eliminated from the diet for 2-3 weeks and then reintroduced for another 2-3 weeks. If in the period without milk the baby does not show symptoms, which on the contrary reappear when it is reintroduced into the diet, there is the confirmation that it is an adverse reaction to food.
It is based on clinical history: or on the relationship between milk consumption and symptoms.
And to ascertain that it is really lactose intolerance you can perform the lactose breath test: that is, the child is made to take a quantity of lactose dissolved in water and the quantity of hydrogen in the breath is measured, because hydrogen is produced by bacteria starting from undigested lactose so its concentration is proportional to the degree of poor digestion of the patient .
In case of nocturnal recurrent abdominal pain, persistent vomiting, dysphagia, recurrent fever, weight loss or stunted growth, it is better to investigate more thoroughly to rule out an organic pathology. In the absence of these symptoms, once the diagnosis of lactose intolerance is made, milk is excluded from the diet.
In case of food intolerance, the food that causes the reaction must be eliminated from the diet or consumed in small quantities. In the case of lactose, therefore, milk and some derivatives: the more aged cheeses the less lactose they contain, there is very little of it even in yogurt and other dairy products based on milk already digested by added bacteria, while pay attention to the labels of ready-to-eat foods as they may contain lactose.
The pediatrician may consider it appropriate to suggest food supplements to ensure the correct calcium intake.
However, it is not always necessary to completely eliminate milk (and fresh cheeses), because it is enough not to exceed the amount of lactose that can be tolerated without triggering symptoms. Therefore, it is a question of identifying the maximum tolerated dose of milk and sticking to that dose in the baby's nutrition.
If lactose, therefore milk sugar, can trigger intolerance, milk proteins can cause allergic reactions.
A food allergy refers to an abnormal response of the immune system, triggered by contact with a food labeled as an enemy. In particular, milk allergy triggers the reaction (excessive production) of IgE antibodies.“Milk allergy can appear in the first months of life. You become allergic after contact with the allergenic food, "he explains.
In case of allergic reactions in infants, the cow's milk proteins they are the first to keep under control because the artificial formulas that replace breast milk are based on cow's milk. Later, by gradually enriching the child's diet, other foods can cause allergies. The most frequent are:
- the egg;
- with growth also fish (cod, trout, sole);
- some types of nuts and legumes (Brazilian nut, almonds, hazelnuts, peanuts).
- a food allergy
- a lack of digestive enzymes (as in the case of lactose intolerance due to lactase deficiency)
- a defect in sugar metabolism (eg fructosemia);
- toxic effects of the food (for example due to contamination of anisakis, the parasite present in raw or undercooked fish, poisoning by mushrooms);
- gluten intolerance (celiac disease);
- idiosyncrasy (abnormal reaction in relation to the amount of food, to food additives).
The most feared symptom of a food allergy is it anaphylactic shock: breathing difficulties, sudden drop in blood pressure, unconsciousness. In this case, you need to go to the emergency room right away.
"In most cases the reactions are borne by the contact organs, therefore the digestive system - with vomiting, abdominal pain, diarrhea, bloody stools - and the skin, with immediate skin reactions" explains the hospital allergist pediatric Infant Jesus.
In fact, the symptoms generally appear from a few minutes to a few hours after the meal that caused contact with the allergenic proteins. Therefore, the appearance of such reactions after giving the bottle or after the baby has drunk a cup of milk can raise the suspicion of food allergy. Even if these are not specific symptoms: very often they depend on other gastrointestinal diseases such as acute infectious gastroenteritis or other inflammatory bowel diseases.
Allergy can also trigger respiratory reactions: rhinitis, conjunctivitis, cough, asthma. As well as the atopic dermatitis of the first year of life can be aggravated by a food allergy.
To diagnose milk protein allergy, we start from clinical history of child (familiarity, symptoms, interval between food intake and appearance of clinical signs) and proceed with a thorough examination (physical examination).
To confirm the suspicion, the prick test. È a skin test: that is, a drop of food extract is applied to the skin of the forearm, the skin is gently pricked and the local reaction is observed. And to complete the diagnostic process, blood is taken to look for the IgE antibodies specific (GROWTH test).
The decisive proof, however, to prove that milk is indeed the cause of the symptoms, is its exclusion from the diet (for 2-3 weeks). “If the symptoms are still present, we must necessarily conclude that milk has nothing to do with the ailments we are trying to diagnose. If, on the other hand, the symptoms have disappeared or are reduced, the food will have to be introduced again (load test) in an adequately equipped hospital environment, so that in the event of serious adverse reactions, appropriate action can be taken. If the symptoms reappear, we will have unequivocal proof of milk allergy, ”he explains.
At this point, if the trigger test shows that the disturbances are caused by milk, it should be eliminated from the diet. At least up to 5-6 years: in fact, at this age the vast majority of allergic children recover.
"We cannot rely on alternative methods for diagnosis: only the dosage of specific IgE, the skin test and above all the load test are able to unmask a milk allergy" he stresses. He adds: «Milk allergy should not only be suspected in the face of severe reactions, but also when a child has frequent diarrhea, eczema, poor growth and / or persistent asthma. Furthermore, when eliminating milk from the diet, it is also necessary to remove cheeses, sweets and ice cream; but it is not necessary to remove foods that contain lactose because it is not a protein but a sugar »."Exclusion diets must be prescribed by the pediatrician allergist" recommends Novembre.
In cases where allergies do not resolve spontaneously after the sixth year of life, a path of desensitize. "Absolutely not to do it yourself" allergists reiterate. This should be done in a hospital with experienced staff dedicated to the management of young patients.
Desensitization consists in introducing milk into the child's diet, first in very small quantities (in general the allergenic food) and then in gradually increasing doses the milk, in order to educate the intestine to recognize and tolerate it.Inadvertent intake of allergenic food
Symptoms caused by inadvertent intake of cow's milk should be treated according to the severity of the reaction. If urticaria, swelling, rhinitis, spasms (bronchial and / or laryngeal) appear there is a strong risk that the child will undergo anaphylactic shock: therefore, it is necessary to promptly resort to emergency therapy (self-injectable syringe of adrenaline, antihistamine and cortisone) and take the child to the nearest first aid.
Cow's milk alternatives
Breast milk is the best food that can be offered to babies. Because of this the World Health Organization recommends exclusive breastfeeding for at least the first 6 months and then as long as possible, according to the wishes of mother and baby. If the mother is not breastfeeding, cow's milk is widely used as a substitute for her (in formulated cow's milk), but what to do with boys and girls who are allergic to its proteins and, albeit in very small numbers, intolerant to lactose?Read also: Milk for babies after 12 months
Only breastfed infants and children over two years of age do not need to replace cow's milk if adequate calcium is provided (600-800 mg / day).
«As we explain in the World Allergy Organization Journal - he says - when faced with a child allergic to cow's milk, the pediatrician prescribes an avoidance diet and then indicates a substitute. The best is breast milk by removing milk-based products from the mother's diet (to avoid contact with the proteins that trigger the allergic reaction in the baby) ».
Obviously, in case of non-breastfeeding, the pediatrician suggests a replacement formula: which one, depends on the type of allergic reaction, as indicated in the guidelines (Diagnosis and Rationale for Action Against Cow's Milk Allergy) of the World Organization on Allergies.
Why allergy remedy you find. In general, however, there are several alternatives that replace milk in a nutritionally valid way and with an appreciable taste.
In case of severe lactose intolerance, it is possible to replace cow's milk with delactosed milk or with soy milk (to be avoided, however, in the first six months of life due to the high risk of allergization and nutritional risks).
In case of allergy, on the other hand, in the first year of life, it is possible to use hydrolyzed rice formulas (it is one of the least allergenic basic foods), or to baby products based on cow's milk proteins (whey proteins or caseins) subjected to processes of enzymatic digestion, which allow adequate growth pending a spontaneous resolution of the disease which occurs in most cases within the third year of life. In the most serious cases, we resort to foods consisting of mixtures of amino acids, the elementary components of proteins, whose safety is well documented and which provide adequate nutrition by promoting weight gain and promoting growth.
Food allergies and intolerances - Ministry of Health
Allergies and intolerances - Ministry of Health
Food allergy - Bambino Gesù Pediatric Hospital
Lactose intolerance - Bambino Gesù Pediatric Hospital
Food intolerances - Epicenter
The DRACMA Guidelines (diagnosis and treatment of allergy to cow's milk proteins)
Cow's milk allergy: towards an update of DRACMA guidelines
Questions and answers
What is a food intolerance?
«Speaks of food intolerance, and not allergy, when the hypersensitivity to a food and the reaction are not caused by the immune system.
What is a food allergy?
A food allergy refers to an abnormal response of the immune system, triggered by contact with a food labeled as an enemy.
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