Lactose intolerance

Lactose intolerance summary

Lactose intolerance occurs due to the absence or insufficiency of the lactase enzyme that digests this sugar present in milk and dairy products. It can be due to primary causes (such as heredity) or secondary (intestinal cell damage).
Symptoms usually include abdominal pain, gas and diarrhea and occur soon after the patient ingests dairy products. The diagnosis is made by observing the symptoms after ingestion of milk or dairy products. The doctor for requesting some exams such as expired hydrogen test, endoscopy, stool exams, among others.

Excessive water loss through diarrhea is one of the complications. Low intake of calcium and protein can result in bone problems. Treatment is usually done with diet modification, replacing dairy products with other foods with a high content of calcium, proteins and minerals. The doctor may also recommend taking lactase, an enzyme that digests lactose.

If you are lactose intolerant, make sure the foods you eat are low in lactose. Replace it with products rich in proteins and minerals, and consult your doctor if you need more information.


Lactose intolerance is a difficulty in digesting lactose due to insufficiency or absence of a digestive enzyme: lactase, also known as beta-D-galactopyranosyl (1 → 4) D-glucopyranose.

Lactose is a sugar found in mammalian milk, composed of glucose and galactose.


In approximately 70% of the inhabitants of our planet, lactase becomes inactive after the age of 6. In other words, about 70% of the world’s population suffers from mild or more severe lactose intolerance.
Northern European Caucasians are generally unaffected by lactose intolerance because of genetic mutations that allow for lifelong lactase production.

In the United States, the Mayo Clinic estimated in 20201 that about 30% of Americans have difficulty absorbing lactose (in English:lactose malabsorption).


A healthy person uses lactose as a source of energy. To absorb it, the body must break down lactose into glucose and galactose in the small intestine by the enzyme lactase or beta-galactosidase. This lactase activity is high at birth and gradually decreases with age. However, the minimum adequate rate for digesting consumed milk sugar is preserved.
Insufficient production (hypolactasia) or absence (alactasia) of this enzyme in the small intestine is a source of lactose intolerance. In this way, there is a certain amount of undegraded lactose converted into gas and acid by the bacteria that live in the colon. These gases and acids inflate the stomach and cause pain. In addition, the milk sugar creates an influx of water into the intestines and softens the stool. This mechanism results in diarrhea..

Lactase deficiency can be primary or secondary. Primary or acquired lactase deficiency may be linked to heredity (genetics). Is intestinal cells or enterocytes are intact. Secondary or temporary deficiency, on the other hand, arises after an attack that can cause reversible cellular damage in the intestine.

These attacks can come from allergic phenomena, parasites, malnutrition, infections or after the use of certain medications. Lesions are transient in this case. Celiac disease and Crohn’s disease can also injure enterocytes. In these cases, the damage can be permanent.

This condition can be congenital or develop throughout life. The first, which is rare, has a hereditary character with normal enterocytes. Here, the symptoms occur from birth to the first feeding. If the child is premature, lactose intolerance is then called developmentally linked. Its evolution is favorable as the intestinal cells mature.

Depending on circumstances, some people produce less lactase. For other patients, this enzyme production may be completely stopped.


First important observation is that lactose intolerance is not a dangerous disease for health, but the symptoms can be very unpleasant.

Signs of lactose intolerance usually appear from the age of five. They are mostly characterized by diarrhea, bloating, abdominal pain or gurgling cramps, gas emissions and nausea. The patient may vomit or become constipated .

These main symptoms occur between 30 minutes and two hours after consuming dairy products. The incubation period can last up to 2 or 3 days.

In addition, some patients may experience mild signs such as chronic fatigue, depression, dizziness, headaches, pain in the limbs, or difficulty concentrating.

It should be noted that the intensity and speed of onset of manifestations vary with the amount of lactose ingested, the rate of beta-galactosidase produced in the small intestine, the mode of ingestion of milk or its derivatives, the transit time, the state of the flora bowel and patient health. There is, therefore, a tolerance limit for each individual.

Three forms of lactose intolerance:
We can distinguish 3 forms of lactose intolerance:
– Primary lactose intolerance. It is the most common form of lactose intolerance. In this form, there is a decrease in lactase production, especially in adulthood. Primary lactose intolerance is influenced by genetics. Certain ethnic groups are most at risk: Africans and African Americans, Latinos and descendants, and inhabitants of southern Europe and the Mediterranean region.
– Secondary lactose intolerance. This form usually occurs after an accident or trauma to the small intestine, for example after surgery or injury. Certain diseases are associated with lactose intolerance, such as Crohn’s disease .
– Congenital intolerance to lactose. This rare form affects babies, they are born with a complete lack of lactase production.


The diagnosis of lactose intolerance is based on symptoms after ingestion of milk or its derivatives. This result is confirmed by a physician after interviewing the patient.

It is possible that the health professional prescribes a test that consists of avoiding dairy products for two weeks, with consumption after that period. If the signs return, lactase deficiency is likely.

Currently the breath hydrogen test, carbon-13 lactose test, endoscopy, biopsy, blood, stool and breath tests are also techniques used in hospitals to diagnose lactose intolerance.

There are also genetic tests that can identify lactose intolerance.


The biggest complication is water loss due to diarrhea and this can be fatal, especially for young children.

As milk and dairy products provide a large amount of protein and calcium , people who are deprived are exposed to the consequences of hypocalcemia, such as growth retardation and osteoporosis .


A low-lactose diet, that is, little milk, reduces the symptoms of patients. The lactose-free diet is the rule for those who do not produce any amount of the enzyme. However, milk and other dairy products without lactose are available in the market. You should know that it is not possible to naturally increase the production of lactase in the human body2.

In the case of a primary intolerance, consumption of up to 240 mL of milk is generally well tolerated. But taking a larger amount requires the use of drugs containing lactase, which helps the body digest dietary lactose. It can be taken either before the meal and is mixed with dairy products in order to prevent symptoms. In general, lactase-based medicines, sold in the form of pills or drops, are sold without the need for a prescription.

Also, foods rich in calcium, protein and mineral salts are highly recommended.

For secondary intolerance, treatment is the cause of the underlying disease without milk restriction, even if the child is exclusively breastfed.

The gradual introduction of milk into the diet may also improve tolerance.


The nutrients in milk can be replaced by other foods. For example, meat, fish, eggs, soybeans, beans and seaweed provide protein. As for vitamins, calcium and mineral salts, these can be found in almonds, hazelnuts, algae, walnuts, figs, dates, dandelions, watercress, soybeans, shellfish, barley or germinated wheat.


– Make sure that the foods and medicines you consume do not have or have a low amount of lactose.

– Yogurt and cottage cheese are better tolerated.

– Skimmed milk is more aggressive than whole milk.

– Evaluate your own upper limit after each intake of dairy products.

– Divide the intake of dairy products into small amounts throughout the day.

– Make sure the milk nutrients are present in the substitute feed.

– Eat foods rich in calcium, such as oysters, canned sardines with bones, oranges, leafy greens, seaweed, soybeans, beans and other legumes.

– Mix milk with other foods.

– Eat foods that contain probiotics. Probiotics are rich in “good” bacteria and can improve symptoms of lactose intolerance. You can find them, for example, in yogurt, juices, soy drinks, in capsule, tablet or powder form.

– See your doctor if:
> You have repeated bouts of diarrhea with abdominal pain and bloating.
> You need other practical advice.

Jeanne Kenney
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I’m a stylist trainer, a content creator, and an entrepreneur passion. Virgo sign and Pisces ascendant, I move easily between my dreams, the crazy world I want, and my feet on the ground to carry out my projects.

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