In recent years, the topic of lactose intolerance has become especially relevant. Noticing unpleasant symptoms in themselves, people began to doubt the benefits of dairy products.

On the one hand, milk contains calcium and is prebiotic; on the other hand, it can cause poor health, chronic fatigue, and even headaches. 

How do you find out what lactose intolerance is, how it manifests itself and what to do if it appears? 

What is lactose intolerance?

Lactose is a type of natural sugar found in milk and dairy products. The breakdown of this carbohydrate into glucose and galactose occurs in the small intestine with the participation of the enzyme lactase. As soon as its activity decreases, lactose intolerance develops. In this case, undigested lactose passes into the large intestine, causing instant disturbances in the digestive system and general well-being. 

Reference: in humans, as in most mammals, the maximum lactase activity occurs in the thoracic period. This natural mechanism gives mother’s milk better absorption in newborns. 

After the cessation of breastfeeding, lactase activity gradually decreases as the baby switches to an adult type of nutrition, in which milk is not the basis of the diet but part of it. 


Why is it important to know if you have an intolerance?

Any food intolerance causes chronic diseases, gastrointestinal diseases, and nervous disorders and is also fraught with excess weight. 

With food intolerance, large undigested fragments enter the intestines. This makes it difficult to absorb them, so the immune system perceives them as foreign and begins to fight them.

Chronic inflammation occurs in the affected tissues and organs, leading to a deterioration in their work. And the immune system, instead of concentrating on external attacks of viruses and microbes, is forced to suppress food antigens. Over time, its resources become insufficient to work on two fronts, so mild ailments develop into chronic ones: headaches become migraines, and a bad mood becomes depression.

The reasons

There are primary (congenital) and secondary (acquired) lactose intolerance. 

The primary one is genetically determined, namely, a mutation in the MCM6 gene.

The following factors can affect the appearance of secondary lactase deficiency:

  • Any disease of the small intestine and intestinal mucosa;
  • Inflammatory diseases (including influenza);
  • Allergic processes;
  • Taking certain medications;
  • Pathology of the pancreas;
  • Operational interventions;
  • Premature birth.


The characteristic symptoms of lactose intolerance can appear approximately 30-120 minutes after eating dairy and milk-containing products (cheese, cottage cheese, ice cream). 

You may notice the following signs:

  • Flatulence (increased gas formation).
  • Cramps and swelling in the abdomen. This is explained by the fact that in the intestine, bacteria break down lactose into gases: CO2, CH4, and H2.
  • Nausea.
  • Diarrhea (loose, sour-smelling stools), as large amounts of undigested lactose draw fluid into the intestinal cavity. The stool may also be green in color and/or contain food particles.
  • Abdominal pain.
  • Weakness.
  • Reduced performance.

The severity of the described conditions can vary from mild to pronounced. These symptoms may not bother you if you have a mild enzyme deficiency. 

An interesting fact: the results of scientific studies show that the peoples who actively engaged in pastoralism hundreds of years ago today demonstrate medium and high lactose tolerance. Thus, the prevalence of lactase deficiency in the Scandinavia population is less than 10%, and in Southeast Asia – more than 90%.

Milk Allergy and Lactose Intolerance: Are They the Same?

Lactose intolerance and milk allergy are completely unrelated concepts. 

People who are lactose intolerant can consume dairy products in a controlled manner. And patients with a milk allergy should not consume even the minimum amount of this product. Otherwise, an immune system allergic reaction is observed in the production of mediators, such as histamine, or a T-cell inflammatory reaction. 

Histamine is produced in several parts of the body and results in the following symptoms:

  • Difficulty breathing;
  • Throat tightness;
  • swelling of the nose, eyelids, and throat;
  • Rash on the skin;
  • Vomit.

Diagnostic methods

In one case, the clinical picture of lactase deficiency may not require additional studies since the symptoms manifest themselves quite clearly. 

But in several other cases, lactose intolerance proceeds blurry, masquerading as other problems and diseases. For example, the patient may experience bloating without disturbing the stool, or vice versa. 

Modern science offers the following diagnostic options:

  1. Eliminative (exclusive) diet.

In this case, all products containing even a small proportion of milk are excluded from the patient’s menu for a certain period. The method allows you to track the patient’s condition in dynamics and see the disappearance of disturbing symptoms. 

  1. Immune health.

This modern diagnostic method allows you to identify hidden individual food intolerance. It is enough to go through the usual blood donation procedure to find out which foods your immune system is positive for and which are hostile.

Next, the laboratory will check your body’s response to 111 antigens. The result of the study is a list of foods you are allowed to consume, which ones with caution, and which ones are better to exclude from the diet completely.

  1. Hydrogen test with lactose.

The test is based on determining the concentration of hydrogen in the patient’s exhaled air. Measurements of its concentration are made first on an empty stomach and then after using lactose. 

Why is hydrogen measured? Because it is he who is released during the breakdown of carbohydrates by bacteria in the colon. In our case, during the breakdown of lactose. In patients with lactase deficiency, the hydrogen content increases, which is associated with the increased bacterial breakdown of lactose in the colon. 

  1. Benedict’s test.

Normally, carbohydrates in the feces of adults should be absent. If they are found, the sample is considered positive, and then we can talk about the presence of lactose intolerance in the patient. 

Differential diagnosis is necessary to avoid confusing the disease with intestinal infections that have typical manifestations.

Treatment of lactose intolerance

With a confirmed diagnosis:

  • Limit foods containing lactose;
  • Enzyme preparations that break down lactose are prescribed;
  • The daily rate of calcium is compensated with the help of other foods or with the help of medications;
  • If necessary, the doctor can prescribe antidiarrheal drugs and complexes that restore intestinal biocenosis. 

How to replace dairy products

Currently, patients with lactose intolerance have no difficulty compiling a daily menu. There are health food stores where you can buy products labeled “Lactose-Free.”

As for cow’s milk, the choice of alternatives is great: almond, soy, banana, and so on.  

Brief conclusions

Lactase deficiency is quite common in the modern world. It leads to unpleasant symptoms after drinking milk or dairy products. As soon as the patient feels the previously described changes in his condition, it is important to contact a specialist for a competent diagnosis. 

To prevent lactose intolerance from developing into acute food intolerance, it is important to follow the diet and all the recommendations of the attending doctor.  

  1. A. A. Baranova “Food Allergy”.
  2. Olds, LC, Sibley, E. Lactase persistence DNA variant enhances lactase promoter activity in vitro: functional role as a cis regulatory element.
  3. A. Muraro Food allergy and anaphylaxis EAACI guidelines Muraro.


Please enter your comment!
Please enter your name here