Lactose Intolerance – Knowledge Compendium

Lactose intolerance is a disorder that often occurs in adults. It is characterized by a reduced ability of the body to digest this sugar. Since the body cannot digest lactose, it irritates the lining of the intestines, causing diarrhea. Lactose intolerance  is a symptom of malabsorption syndrome.

This abnormality can vary in severity, ranging from mild discomfort to severe pain and damage to the intestines.

Absorption of lactose

Lactose is a disaccharide carbohydrate composed of two monosaccharides: glucose and galactose. You will find it in dairy products. The human body absorbs lactose at the cellular level in intestinal cells, also known as enterocytes.

These cells are cube-shaped and have microvilli where they make contact with the inner wall of the intestine.

The microvilli form an irregular structure called a brush border. This is the area where most of the nutrients are absorbed.

Some of these ingredients must first be separated and broken down into smaller, simpler compounds. Only then is it possible to absorb them into the bloodstream. This is the case with lactose. Lactase must first break down into a glucose molecule and a galactose molecule. Then it is possible to assimilate lactose.

Lactase is an enzyme found on the brush border of enterocytes. It is present in uneven amounts along the entire length of the digestive system. The greatest amount of lactase is found in the first sections of the small intestine – in the duodenum and in the jejunum.

In some ethnic groups, lactase secretion decreases with age and stops when a person reaches maturity. However, in white people, the secretion of lactase is not interrupted.

Lactose intolerance: pathogenesis

From the point of view of pathogenesis, we are talking about a lack of lactase due to two possible causes. First, the enzyme may not be synthesized at all. Second, a lack of lactase may be the result of an intestinal disease.

Primary lactose intolerance

First of all, it’s important to remember that primary lactose intolerance is the most common type of lactose intolerance in the world. It is a separate disease entity – it is not caused by any other diseases.

When this occurs, the body fails to synthesize lactase for various reasons, such as:

• Congenital lactase deficiency: in this case it is an inherited disease. Lactase is not produced due to a genetic abnormality. Both parents must have this mutation for the child to inherit it. This means that the gene that causes congenital lactase deficiency is a recessive gene. This is rare, but children who inherit these genes do not synthesize lactase and are therefore lactose intolerant from birth.

• Developmental lactose intolerance  can occur in babies born too early. It especially affects babies born before 32 weeks of gestation, because then the lactase has not yet reached its maximum value.
• Physiological deficiency: We have already mentioned that lactase synthesis decreases after the end of breastfeeding. This happens very often in Asian and African women. Such intolerance occurs at different times in life. It often happens that in people of these races it affects children around 5 years of age. However, it is less common in white people and appears later in life.

Secondary (acquired) lactose intolerance

Changes in the intestinal mucosa resulting from other issues result in the patient developing secondary or acquired lactose intolerance. Depending on the cause, this type of lactose intolerance may be permanent or reversible. Occasionally, the underlying abnormalities can be healed.

Moreover, this type of intolerance may be related to changes in the microvilli. Disorders of this type prevent the normal absorption of carbohydrates. This leads to inflammatory diseases such as, for example, Crohn’s disease or ulcerative colitis.

Moreover, this type of lactose intolerance occurs with intestinal infections that alter the lining of the digestive system. It particularly affects children.

Lactose intolerance: symptoms

As a result of lactose intolerance, the irritation that appears after consuming dairy products will cause the following unpleasant symptoms:

• Overproduction of gases
• Nausea and vomiting
• Pain and gas
• Strong osmotic diarrhea

The severity of these symptoms may vary  and will depend on the severity of your intolerance. There are people who cannot drink milk but can eat dairy products such as cheese and yoghurt. In many cases, symptoms are mild and most patients can consume small amounts of milk.

When the lactase deficiency is due to a genetic condition  or occurs early in a child’s development, the toddler may experience significant developmental delays. The consequences can then be very serious.

Diagnostics of lactose intolerance

Many people suspect they are lactose intolerant on the basis of digestive symptoms that appear after consuming milk.

However, there are also tests and studies that can diagnose primary lactose intolerance:

• Lactose tolerance test. If your body is properly digesting lactose, your blood sugar level should increase after you eat or drink a dairy product. In this test, the patient is given lactose to drink and then the sugar concentration is measured. If the glucose level does not rise by at least 20 md / dL, the patient is lactose intolerant.
• Hydrogen breath tests (HBT). As already mentioned, fermentation by bacteria leads to the production of large amounts of hydrogen in the large intestine. This gas is absorbed into the bloodstream and reaches the lungs and is then exhaled with the air. Therefore, a useful test in the diagnosis of lactose intolerance is the measurement of the hydrogen content in the exhaled air of the patient who has consumed lactose. Above average values ​​may indicate that a person is not properly digesting lactose.

• Stool acidity test. The human body gets rid of some of too much hydrogen by passing it through the stools. This lowers the pH level of the stools and makes it acidic.

If the results of this type of test do not meet the standards, the person is most likely lactose intolerant.

Lactose intolerance is in most cases not a serious medical condition. Fortunately, symptoms can be eliminated by simply excluding lactose from your daily diet or significantly reducing the amount of lactose.