Lactose intolerance – symptoms and manifestation in children and adults

The digestive system is complex because it has to perform many functions. It contains a large number of enzymes that are responsible for the digestion of products. With their shortage or, conversely, in excess, disorders of the gastrointestinal tract begin. A common type of such deviation is lactose intolerance – a process in which lactose is partially or completely not processed.

What is lactose intolerance?

This is a violation in the work of the digestive tract, characterized by absolute or partial non-perception of lactose, due to the lack of an enzyme responsible for the digestion of dairy products (a substance called “lactase”). The first symptoms of pathology appear in adulthood and adolescence. In newborns, a decrease in the activity of lactase in the intestine is extremely rare. Alactasia (another name for milk intolerance) can occur due to various factors, including heredity, acute intestinal infections, etc.

The benefits of lactose for the body

The disaccharide carbohydrate in milk, which is a product of the breakdown of galactose and glucose, is called lactose (aka “milk sugar”). This is a rich source of energy, necessary for the growth, development and maintenance of the body’s functionality. The beneficial properties of lactose are:

  • help in the growth of muscle tissue;
  • participation in the absorption of calcium;
  • prevention of the development of diseases of the nervous system;
  • strengthening the walls of blood vessels, thereby reducing the risk of developing pathologies of the cardiovascular system;
  • maintaining a healthy intestinal microflora, since lactase serves as an optimal environment for the life of lactobacilli.

Causes of Intolerance to Dairy Products

There are primary (congenital) and secondary (acquired) hypolactasia. In the first case, the pathology develops shortly after the start of feeding the newborn with breast milk or infant formula. With secondary lactose intolerance, clinical symptoms can occur at any age under the influence of various factors. A genetic predisposition to hypolactasia is a disease whose developmental causes are not fully understood.

Doctors are convinced that the racial affiliation of a person plays an important role: for example, a high percentage of enzyme disorder is observed in the inhabitants of Africa and Asia, Jews, and southern peoples. Rarely there are people who completely lack the enzyme that breaks down lactose, and such cases are recorded exclusively in the native inhabitants of North America.

In addition to the genetic factor, heredity also affects the development of congenital lactose intolerance. The chance of having a baby with an allergy to dairy products is much higher if one or both parents have this disease. The risk group also includes infants born ahead of time. Other likely causes of lactose intolerance are:

1. Celiac disease. This pathology is characterized by damage to the small intestine villi by gluten, a component of cereal food. According to one theory, due to the lack of special enzymes, this protein accumulates in the mucous membrane of the organ, acting on it poisonously. According to immunological theory, one of the components of gluten causes the formation of an immunological reaction, the result of which is hypolactasia.

2. Crohn’s disease. The disease can affect any part of the intestine. In the areas of inflammation, ulcers appear, microflora are disturbed, gastroenterological problems arise. Against the background of allergies, enterocytes (intestinal epithelial cells) are damaged by immunoallergic complexes. They settle on the intestinal mucosa, resulting in a decrease in the ability of red blood cells to secrete lactase.

3. Overload of milk proteins. More often this deviation occurs in newborns. The amount of enzymes in breast milk differs at the beginning and end of feeding. In the first servings, there is more lactose, so the baby quickly receives a large volume of this component. His intestines are not always able to quickly digest a lot of lactose, resulting in temporary signs of alactasia.

Factors contributing to the development of hypolactasia

Intestinal infections (dysentery, intestinal flu, salmonellosis) are a common cause of a decrease in the production of lactase needed for milk protein processing. The disease occurs due to dysbiosis, in which there is an imbalance between good and bad microflora. Another mechanism for the development of an ailment affecting the small intestine is due to damage to red blood cells. Moreover, the severity of hypolactasia depends on the pathogenicity of bacteria and viruses. Risk factors for the development of pathology are:

  • age (mature and elderly people are more prone to lactose intolerance);
  • radiation therapy (patients who underwent radiotherapy have reduced immunity, which can lead to alactasia);
  • ethnicity (Africans, Asians have an increased risk of developing the disease);
  • premature birth (premature babies are at risk, but early diagnosis and proper treatment in most cases give a positive result.

Types of hypolactasia

Modern medicine distinguishes two main types of pathology associated with the inability of the body to fully or partially digest milk protein. Alactasia is classified as follows:

1. Genetically inherited. The most common type of disease that usually occurs in people over 20 years old.

2. Chronic (acquired). It develops against the background of problems with the small intestine (unbalanced diet, previous operations on the intestines, ulcerative colitis, Crohn’s disease, celiac disease, gastroenteritis, chemotherapy).


The reason for the development of lactose intolerance is a gene mutation. This is a relatively rare phenomenon in which the symptomatology of the disease in the child manifests itself immediately after birth. Types of congenital hypolactasia include:

  1. Alactasia of the newborn. The disease is difficult, requiring strict adherence to the diet. One of the reasons is the immaturity of the enzyme system, due to which the baby is unable to digest milk protein. Lactase is absolutely inactive.
  2. Congenital failure with late onset. It appears at a later age. Occasionally, the first symptoms occur in children from 5 years old, but more often the disease develops after 20 years. Congenital hypolactasia with a late onset is milder compared to other species.
  3. Transient failure of premature infants. It occurs in children born earlier than the due date. The peculiarity of the disease lies in a transient character. When milk protein enters the body, crumbs can develop metabolic acidosis – a decrease in blood pH. Violations are due to the immaturity of the infant’s enzyme system.

Acquired (secondary)

The onset of the disease is associated with diseases that destroy the membrane of the small intestine. These include dialkia, irritable bowel syndrome. In addition, secondary hypolactasia may occur due to resection of the small intestine. This form of pathology is manifested due to the defeat of enterocytes, at the same time there is a violation of the synthesis of sucrose and trehalose – enzymes necessary to ensure normal digestion.

The risk of acquired alactasia naturally increases with age. Sometimes in preschool children, an allergic reaction to milk occurs without the intervention of additional factors, with a decrease in the level of lactase below the permissible norm. Acquired lactose intolerance is manifested as a result of one or more negative factors:

  • intestinal infections;
  • stress
  • malnutrition;
  • intestinal dysbiosis;
  • ulcerative formations;
  • worms;
  • overuse of milk for a long time, especially in adulthood.

How does it manifest

Lactose intolerance is divided into full or partial: the form depends on the amount of production of the lactase enzyme. With an absolute inability of the body to digest milk protein, the entire spectrum of symptoms of the disease is observed, with partial hypolactasia, the signs are less intense. Symptoms can be caused by a number of other pathologies, since it does not have specific features. Nevertheless, if it is observed after consuming dairy products, then there is no doubt about the presence of lactose intolerance.

Signs of Adult Lactose Intolerance

The intensity of the manifestation of the clinical picture depends on the degree of lactase production in the human body. As a rule, the symptoms of the disease become noticeable within 30-120 minutes after eating dairy products. Characteristic for adults signs of lactose intolerance are:

  • loose stools (but not frequent, as with diarrhea);
  • bloating, rumbling of the abdomen;
  • constipation;
  • nausea, vomiting;
  • belching;
  • discomfort, pain in the peritoneum;
  • convulsions (with absolute alactasia);
  • flatulence;
  • loss of appetite;
  • the presence in the feces of mucus;
  • tachycardia.

Symptoms in infants

The disease in babies is expressed differently, depending on the volume of the produced enzyme and the reaction of the body to it. In this regard, children with hypolactasia are divided into several groups:

  • Kids who are able to consume 1 glass of milk per day without negative consequences, while they digest dairy products without problems.
  • Children who do not tolerate milk and can consume fermented milk products only in limited quantities.
  • Babies whose digestive system reacts equally badly to milk and dairy products.
  • Children whose symptoms of alactasia occur even when consuming foods containing a small percentage of milk.

Signs of lactase deficiency are noticeable in children from the first days of their lives. Symptoms are manifested by breastfeeding or the use of baby formula. The disease is diagnosed by the following symptoms:

  • the baby’s tummy is swollen, tense (this is noticeable during visual examination and palpation);
  • increased gas formation (because of it moodiness occurs, the child loses his appetite, cries, is anxious);
  • the consistency of bowel movements becomes liquid, foamy, the smell of feces is acidic, there are impurities of mucus;
  • the number of bowel movements increases or constipation occurs (the last symptom is characteristic of babies with artificial feeding);
  • spitting up after eating;
  • since most of the substances of the food consumed are not absorbed, in infants the weight gain slows down;
  • the baby may be tormented by colic, nausea, vomiting;
  • allergic rashes on the skin, swelling of the mucous membranes appear.

Diagnosis of lactose intolerance

Anamnesis and a general examination are not able to give an accurate diagnosis, so the doctor prescribes a number of laboratory tests, during the passage of which it is extremely important to follow all the rules of preparation. Key methods for examining adults for lactose intolerance are:

  1. General and biochemical analysis of blood. This study measures blood sugar after consuming a milk protein product. Analysis of lactose intolerance is carried out exclusively on an empty stomach. On the day of the procedure, the patient drinks a liquid containing lactose, after which every 30 minutes for 2 hours blood is taken from him. If the sugar level in it does not increase, this may indicate alactasia. This study is not used for the diagnosis of patients with diabetes and infants.
  2. Fecal tests. As a rule, several types of studies are carried out at once. Analysis of carbohydrate content in feces helps to identify their share. Since lactose is a carbohydrate, with a deficiency of lactase, their amount is increased. Deciphering this study is difficult because the analysis technique is not able to distinguish galactose from lactose and glucose. The results, in this regard, are only indicative, therefore they are considered exclusively in combination with the clinical symptoms of the patient. Another research option is fecal acidity analysis. The appearance of undigested milk protein in feces causes its strong oxidation, therefore, with a pH value below 5.5, there is reason to suspect alactasia.
  3. Lactose intolerance test. There are different types of testing, among which they often resort to analysis using an indicator strip and hydrogen research. The patient is given a drink of a solution of milk sugar (50 g of substance per 100 ml of water), after which, for half an hour, the level of galactose in the urine is measured several times with a test strip. The hydrogen test also involves the use of lactose, after which several times at equal time intervals determine the level of milk protein in the exhaled air. The amount of hydrogen directly depends on the activity of the microflora of the large intestine: if anaerobic bacteria are forced to digest untreated lactose, they emit a larger amount of this gas than during normal operation of the digestive system. A curve based on these data is analyzed by a doctor.
  4. Intestinal mucosal biopsy followed by histology. This is a very informative diagnostic method (its accuracy is 90–95%). Nevertheless, it is extremely rarely used for examining children, since it requires the introduction of the patient into general anesthesia. Since this method is traumatic, it is extremely rarely used for the diagnosis of hypolactasia in adults.

Lactose intolerance treatment

There are no methods that can completely cure a person from this pathology, therefore, alactasia therapy is aimed at alleviating or completely removing its symptoms. For this, the patient is prescribed a diet that limits or completely eliminates milk protein. In addition, the doctor can prescribe medications for you to stop the clinical manifestations of pathology, vitamin therapy. Treatment is selected individually for each patient, taking into account:

  • age;
  • genesis;
  • degree of enzyme deficiency.

Diet therapy

The basis of alactasia therapy is the complete or partial exclusion of lactulose-containing food from the patient’s menu. Depending on the severity of the symptoms, the patient is advised to refuse either exclusively from milk or from all milk-containing products (cheese, cottage cheese, ice cream, yogurt, milk chocolate, etc.). The list of banned foods also includes:

  • butter baking;
  • meat products such as sausages, sausages, ham, boiled sausage;
  • glazed sweets;
  • sauces (ketchup, mayonnaise, mustard);
  • fast food;
  • fast food dishes – mashed potatoes, soups, vermicelli, jelly in bags;
  • meat offal (brain, kidney, liver);
  • cocoa powder;
  • sweeteners.

The diet should be balanced, so it is important for the patient to monitor the reaction of his own body to a particular product, so as not to exclude wholesome food that is well tolerated. As a rule, a complete exclusion of sour-milk products from the diet is not required, and a person with hypolactase can consume 100-150 ml of kefir per week without consequences. Moreover, not only the volume of servings plays a role, but also the time intervals between the use of dairy products. To make it easier to stick to a diet, you should have a food diary.

Since dairy products contain a lot of useful substances, it is important to replenish their necessary volume with lactose-free substitutes. To help in this case come tofu cheese, soy milk and cottage cheese. Soy products are hypoallergenic and contain large amounts of vegetable protein. With lactose intolerance, in addition, it is allowed to use:

  • fish, shrimp, squid, other seafood;
  • baked, boiled meat (chicken, beef, turkey, rabbit);
  • vegetable oil (olive, corn, linseed, sunflower);
  • rye, wheat, bran bread;
  • vegetables, fruits, natural juices;
  • jams, honey, sugar;
  • dark bitter chocolate;
  • buckwheat, rice, pasta;
  • nuts
  • eggs
  • legumes;
  • coffee, tea.

Nutrition Features

In a serious condition of the child, the issue of switching from breast milk to a lactose-free milk mixture is considered. With a weak severity of signs of lactase deficiency, a nursing mother is prescribed a strict diet. If a woman refuses to consume foods high in milk sugar, the percentage of lactose in her milk will decrease, and the load on the baby’s intestines will decrease significantly.

When diagnosing pathologies in infants, they are transferred to mixtures with a low lactose content or without it at all. Such cereals are rich in all useful substances necessary for growth and development, therefore, parents should not have reasons for concern. In the future, after consulting with a specialist, you can try to gradually introduce a small amount of the usual mixture and milk-containing food into the child’s diet.

local_offerevent_note January 21, 2020

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