4 min read
Lactose Digestion Disorder
Katarzyna Mazur
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Diets Premium Expert • 22.03.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| Diets Premium Expert Katarzyna Mazur | min read 4 min | Scientifically reviewed by a clinical dietitian 22.03.2026 |
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Key Takeaways
Lactose digestion disorder is a global problem. It is estimated that in Poland it affects 37% of the population. The reason for the development of intolerances is a lack of the lactase enzyme, which is used to break down milk sugar lactose. Undigested lactose remains in the intestine, which is the most common cause of gastrointestinal discomfort after consuming dairy products. Is there a way to cope with the exclusion of milk and dairy products from the diet?
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Reasons for lactose intolerance
The understanding of lactose intolerance lies in the knowledge of the etiology of the disorder. A complete lack of lactase, secondary enzyme deficiency, or adult-type hypolactasia are distinguished. Alaktazia, a congenital deficit of lactase, is a total absence of the enzyme, a genetic disorder. Gastrointestinal symptoms appear after consuming the smallest amounts of lactose. Secondary lactase deficiency accompanies chronic conditions and results from damage to intestinal villi. It occurs in the course of acute gastrointestinal infections (e.g., Rotavirus), food allergy, celiac disease, after taking medications, alcohol consumption, or malnutrition. The intolerance is reversible and disappears with the regeneration of the intestinal mucosa. The last type is adult-type hypolactasia, a lactase deficiency resulting from a gradual decrease in lactase levels with age. The lactase activity in adulthood is about 10% of the activity determined in infancy.
What is the symptom complex of intolerance?
Unabsorbed sugar is utilized by bacteria in the digestive tract. During the fermentation of lactose, gases such as hydrogen, carbon dioxide, methane, as well as short-chain organic acids like lactic acid, acetic acid, propionic acid, butyric acid are produced. The breakdown products cause bloating, overflows, abdominal pain, and irritate the digestive tract, leading to diarrhea. A prolonged state can result in dehydration and malnutrition.
Is there a problem with intolerance affecting me?
The diagnosis of intolerance is founded on a medical consultation, a clinical picture, and a direct or indirect diagnostic test. The most frequently employed test is the hydrogen breath test. This entails administering a specific quantity of lactose and subsequently tracking the concentration of hydrogen in the exhaled air. Alternative methods encompass stool pH testing and testing for lactase activity in a biopsy of the small intestine mucosa.
Lactose sources in food
Lactose, a dairy sugar, is present in milk and dairy products and is often added by producers to bakery goods, margarine, ready-made dishes, meat processing products. It is worth noting that lactose is also a component of certain medications.
Dietary method – Practical guidance
The method of lactose intolerance is dependent on the degree of the body's reaction to dairy products. It involves reducing or taking lactose in small amounts while simultaneously providing the enzyme in the form of tablets or excluding products containing lactose. Individuals with reduced lactose sensitivity can consume milk in small quantities at specified intervals. The single intake of a product containing 5–10 g of lactose, such as 100–200 ml of yogurt, should not cause an immediate reaction of discomfort. Patients can consume dairy products containing live bacterial cultures, such as yogurts or kefirs. Bacteria produce lactase – an enzyme that partially breaks down lactose in the digestive tract. A good option is also aged hard cheeses, such as Parmesan or cheddar, which contain small amounts of lactose. There are also products with reduced lactose content, such as lactose-free milk or cheese, available on the market.
Exclusion diet for individuals with lactose intolerance
Individuals with high sensitivity should avoid milk, dairy products, and so-called lactose-deficient sources. Even minimal amounts can lead to unpleasant gastrointestinal discomforts. As a result of introducing restrictions, affected individuals are at risk of developing deficiencies in certain nutrients such as calcium, vitamins B1 and B12. When establishing a diet plan, products that provide missing nutrients should be taken into account. Sources of calcium in the diet of individuals with lactose intolerance include, for example, calcium-fortified soy drinks, coconut milk, tofu, fish, herring, beans, seeds, broccoli, barley, figs, oat flakes. It is worth noting, however, that the absorption of calcium from these products is lower than from milk and dairy products. Sources of vitamin B2 in the diet of individuals with lactose intolerance include, for example, soy drinks, buckwheat, barley, oat flakes, legumes, Brussels sprouts, spinach, broccoli. Rich sources of vitamin B12 are meat, liver, fish, and eggs.
The Impact of Vitamin D Levels on Calcium Content in the Body
Insufficient levels of vitamin D can disrupt the body's calcium metabolism. Apart from milk, vitamin D is found in food products such as eggs and fish, but it is not enough as the sole source. In order to obtain an adequate amount of vitamin D, sun exposure is required. In moderate latitudes, 10 to 15 minutes of sun exposure from May to August with exposed forearms and lower legs (without filters) is sufficient. Individuals who do not spend time in the sun require an annual supplementation or intake of vitamin D from September to the end of April. For children and adolescents (1-18 years of age), a daily dose of 600-1000 IU/day is recommended, for adults 800-2000 IU/day, and for athletes 1000-2000 IU/day. It is recommended to check the vitamin D level by performing a test of the 25-hydroxy-vitamin D level in the blood.
Katarzyna Mazur
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