Lactose intolerance: symptoms, causes and lifestyle advice

Bloating, stomach cramps, diarrhoea after a delicious latte or a slice of cheese? Many people experience these unpleasant symptoms but don't always know what's behind them. Lactose intolerance, or lactose intolerance, is a widespread disease that can have a significant impact on the quality of life of those affected. The good news is that with the right knowledge and some lifestyle changes, the condition can be effectively managed.

In this article, we take a detailed look at what exactly lactose intolerance is, what the symptoms are and how it can be diagnosed. We give a detailed medical explanation of the physiological processes behind it and show the role of genetics in its development. We also give practical advice on how to follow a lactose-free diet, how to identify hidden sources of lactose and how to live a full life as a lactose intolerant person. Our aim is to help you understand and manage this condition with reliable and understandable information.

What is lactose intolerance? Medical explanation

Lactose intolerance is a digestive disorder that occurs when the body cannot properly digest lactose, a type of sugar found in milk and dairy products. It is important to distinguish it from milk allergy, which is an abnormal reaction of the immune system to milk protein and can cause much more severe symptoms.

The role of the enzyme lactase

An enzyme called lactase, produced in the small intestine, is responsible for digesting lactose. This enzyme breaks down lactose into two simpler sugars, glucose and galactose, which can then be absorbed through the intestinal wall into the bloodstream. In lactose intolerance, production of the enzyme lactase is reduced or completely absent. As a result, lactose passes undigested into the large intestine.

In the large intestine, gut bacteria start to ferment (ferment) lactose. The by-products of this process are short-chain fatty acids and various gases (hydrogen, carbon dioxide, methane). These gases cause bloating, intestinal distension and abdominal pain. The undigested lactose also attracts water into the intestine (osmotic effect), which makes the stool more dilute and leads to diarrhoea.

Types of lactose intolerance

There are three main types, which differ in the way they develop.

1. Primary lactose intolerance

This is the most common form. In the majority of people, lactase enzyme production naturally declines after infancy and after breastfeeding. The extent of this is genetically determined. In Europe, a significant proportion of the population has a gene variant that allows lactase production in adulthood, but in many people this ability is gradually lost over the years. Symptoms usually first appear in adolescence or adulthood.

2. Secondary (secondary) lactose intolerance

This type is caused by an underlying disease or damage to the small intestine. The cells that produce the enzyme lactase are located on the surface of the mucous membrane of the small intestine and are therefore vulnerable. Conditions such as gastroenteritis (gastritis), Crohn's disease, coeliac disease (gluten sensitivity) or surgery and drug treatments (e.g. chemotherapy) that affect the small intestine can temporarily or permanently reduce lactase production. If the underlying disease is successfully treated, lactase production often recovers.

3. Congenital lactose intolerance

This is a very rare, inherited genetic disorder in which the baby is unable to produce lactase from birth. The symptoms (severe diarrhoea, dehydration) appear immediately after the start of breast or formula feeding. This condition requires immediate medical intervention and special lactose-free feeding.

The most common symptoms of lactose intolerance

Symptoms of lactose intolerance usually appear between 30 minutes and 2 hours after eating a food or drink containing lactose. The severity of the symptoms varies from person to person and depends on the amount of lactose consumed and the degree of individual lactase deficiency.

The most common symptoms are:

• Bloating: An uncomfortable, tight feeling in the abdomen due to a build-up of intestinal gas.
• Abdominal cramps and pain: It is caused by straining of the intestinal wall and increased bowel movements, most often around the navel or in the lower abdomen.
• Diarrhoea: The osmotic effect of lactose in the colon increases the water content of the faeces.
• Increased intestinal gas formation (flatulence): The removal of gases produced during bacterial fermentation.
• Nausea, occasional vomiting: It is less common but may also be a sign of irritation of the intestinal tract.

Less specific symptoms may also be associated with complaints such as headaches, fatigue or concentration problems, although their direct link to lactose intolerance is still under debate.

Making the diagnosis: what tests can you expect?

If you experience any of the above symptoms and suspect that you are lactose intolerant, it is important to consult a specialist gastroenterologist. Accurate diagnosis is essential to develop an appropriate treatment plan and to rule out other diseases with similar symptoms (e.g. irritable bowel syndrome, celiac disease).

From Endomedix Gastroenterology Centre specialists are available with modern and painless diagnostic procedures.

The most commonly used diagnostic methods:

• Exhalation test for hydrogen (H2): It is the most widely used and reliable test. The patient is asked to drink a solution containing a specific amount of lactose. Afterwards, at certain intervals (usually 2-3 hours), he or she must breathe into a device that measures the hydrogen content of the exhaled air. If the lactose enters the large intestine undigested, the bacteria produce hydrogen gas, which is transported through the bloodstream to the lungs and is measured in the exhaled air. A significant increase in hydrogen levels confirms lactose malabsorption (malabsorption disorder).
• Genetic testing: This test can be done from a simple swab of the oral mucosa or a blood sample. It shows whether the individual genetically carries the gene variant responsible for adult lactase persistence (the persistence of lactase production). The test confirms or excludes a primary, genetically determined susceptibility to lactose intolerance. However, it does not detect secondary, acquired forms.
• Elimination diet: Your doctor may recommend that you completely eliminate lactose-containing foods from your diet for a few weeks. If the symptoms disappear during this time and then reappear with the reintroduction of dairy products, it is highly likely that you are lactose intolerant. This method alone is not sufficient for a definitive diagnosis, but it can be a useful part of the investigation.

Lifestyle changes for lactose intolerance: practical tips

The treatment of lactose intolerance is based on diet, i.e. reducing or completely eliminating lactose intake. The aim is not to ban dairy products altogether, but to find the amount of lactose that you can still consume without complaints. This is the individual tolerance level.

1. Learn about the lactose content of foods.

Not all dairy products contain the same amount of lactose.

• Foods with high lactose content: Milk, cream, sour cream, yoghurt (although the live cultures in it help to break down some of the lactose), cottage cheese, soft cheeses (e.g. mozzarella), dairy ice creams, dairy chocolate.
• Low lactose foods: During the long maturing process, most of the lactose is broken down. These include hard, mature cheeses (e.g. Parmesan, cheddar, Swiss) and butter (which contains little lactose due to its high fat content). Many people can eat small amounts of these without complaint.

2. Read the labels! - Hidden sources of lactose

Lactose can be found as an additive not only in dairy products but also in many processed foods. Always check the list of ingredients! Look for the words: milk, milk powder, whey, whey powder, whey, buttermilk, cheese, cottage cheese.

They may contain hidden lactose, for example:

• Bakery products, cakes, biscuits
• Cold cuts, sausages, liver patés
• Prepared dishes, soup powders, salad dressings
• Breakfast cereals, muesli bars
• Certain medicines and food supplements

3. Choose lactose-free alternatives!

Fortunately, there is now a wide choice of lactose-free products. These are traditional dairy products to which a lactase enzyme is added during production to pre-degrade the lactose. You can buy lactose-free milk, yoghurt, sour cream, cheese, cottage cheese and almost all other dairy products.

Plant-based „milks” and products are also an excellent alternative. These include soya, almond, rice, coconut or oat drinks and yoghurts and desserts made from these.

4. Use lactase enzyme preparations!

If you do want to eat lactose-containing food (e.g. in a restaurant or when you are out and about), lactase enzyme tablets or drops available from pharmacies can be of great help. These can be taken before a meal to replace the missing enzyme and help digest lactose, preventing the onset of symptoms. Keep a few grains on you at all times so that you don't have to give up treats in spontaneous situations.

5. Watch your calcium and vitamin D intake!

Dairy products are an important source of calcium and vitamin D. If you significantly reduce your intake, you should ensure that you supplement these nutrients from other sources to maintain bone health.

• Good sources of calcium: Lactose-free dairy products, vegetable milks (often fortified with calcium), leafy vegetables (e.g. kale, spinach), broccoli, sardines (fibre-rich), almonds, sesame seeds, tofu.
• Vitamin D sources: The primary source of vitamin D is sunlight, but it can also be found in seafood, egg yolks and fortified foods. During the winter months, you may want to take a vitamin D supplement on the advice of a doctor.

When should you see a doctor again?

Although lactose intolerance is unpleasant, it is not a dangerous condition. However, if your symptoms do not improve despite your diet, or if you experience any of the following „warning” signs, you should see your gastroenterologist immediately:

• Significant, unintentional weight loss
• Blood in the stool
• Diarrhoea or pain that wakes you from sleep, even at night
• High fever
• Severe, constant abdominal pain

These symptoms may indicate another, more serious illness that requires a thorough investigation.

The path to a complaint-free life

Awareness is the key to living with lactose intolerance. Once diagnosed, the first step is to find out your own tolerance level and personalise your diet. This is a learning process that takes time and patience. Don't be discouraged if you have difficulties at first; a wide range of lactose-free products and lactase enzyme preparations can make the lifestyle change much easier.

If you are unsure about your diagnosis or need help with your diet, please contact the Endomedix Gastroenterology Centre to your specialist doctors and dieticians, who will give you personalised advice to help you on your way to becoming symptom-free.