Lactose intolerance: causes, symptoms and diet
Anyone affected by lactose intolerance is not alone: more than half of the world’s population suffers from it. In cases of lactose intolerance, the body has difficulty digesting lactose, the sugar found in milk and dairy products. In our article, you will find out more about the causes and symptoms of lactose intolerance as well as the foods that those affected should avoid.
Dairy intolerance: lactose is often to blame
If you regularly have problems with your digestion after eating milk or dairy products, it could be due to lactose (milk sugar). Lactose intolerance is widespread. Around one in five people in Switzerland is affected.
What is lactose?
Lactose, also known as milk sugar, is a disaccharide consisting of two sugar molecules, glucose and galactose. It is the main component of sugar in milk and dairy products. Lactose is usually broken down in the small intestine so that it can be absorbed and used by the body. The body needs the lactase enzyme to break it down.
The ability to digest lactose decreases over the course of life. As a key source of energy in breast milk, lactose still plays an important role in the survival of babies. However, lactase activity gradually decreases with age and with increasing preference for other foods besides milk, where lactose does not need to be broken down.
In people with lactose intolerance, production of the lactase enzyme is greatly reduced or absent, making it difficult to digest milk or dairy products.
What is lactose intolerance?
Lactose intolerance occurs when the body does not make enough lactase to digest lactose (milk sugar). The lactase enzyme breaks down lactose into glucose and galactose. The sugar molecules can only be absorbed from the intestine into the blood and used as an energy source in the broken-down form. In the event of a lactase deficiency, undigested lactose enters the large intestine, where it is fermented by bacteria. This leads to the formation of gases and water absorption in the large intestine. Abdominal pain, flatulence and diarrhoea are the consequences (see “How does lactose intolerance manifest?”). Lactose intolerance may be congenital or may develop over the course of life. If lactose intolerance occurs suddenly, it may also be a consequence or side effect of another disease that damages the intestines (e.g. coeliac disease). Lactose intolerance should not be confused with cow’s milk protein allergy.
The symptoms of lactose intolerance can vary greatly from person to person. The most common symptoms include intestinal complaints such as severe flatulence, abdominal pain, diarrhoea and nausea. These usually occur within a few hours of eating lactose (milk sugar).
Symptoms of lactose intolerance
Intestinal:
- Flatulence, abdominal distension, wind
- Abdominal pain, abdominal cramps
- Diarrhoea or loose stools
- Nausea, or less commonly, vomiting
Systemic:
- Headache
- Difficulty concentrating
- Chronic fatigue
- Muscle pain
- Joint pains
- Cardiac arrhythmias
- Mouth ulcers (sores in the mouth or on the lips)
People often notice themselves that they do not tolerate milk and dairy products well and suspect that they are lactose intolerant. It may be helpful for the doctor or specialist if the foods eaten and symptoms observed, along with the times, are recorded in a food symptom diary.
It should be noted that the symptoms of lactose intolerance may also indicate another cause, such as other intolerances. A visit to the doctor is therefore advisable for an accurate diagnosis. Reliable methods to confirm the diagnosis are a hydrogen breath test or a genetic blood test.
Incidentally, although the symptoms of lactose intolerance can be very varied, weight gain is not necessarily one of them. However, it can occur as a side effect because the unpleasant discomfort leads to frustration eating or a lack of exercise. Blemished skin is often associated with lactose intolerance. However, this assumption is not true. The increased sebum production and inflammation of the skin are related to increased insulin production after consumption of milk.
The duration of lactose intolerance symptoms may vary from person to person. In some cases, symptoms may appear within a few hours of consuming milk or dairy products and subside within a day. For others, it may take longer for the symptoms to resolve completely. If the symptoms of lactose intolerance are very severe or persist for an unusually long time, it is advisable to see a doctor.
A key component of the treatment of lactose intolerance is diet. The aim is for those affected to no longer have any symptoms. To this end, foods containing lactose should be avoided or their consumption limited. Particularly when lactose intolerance is not congenital, there is often some residual activity of the lactase enzyme. In these cases, small amounts of lactose are tolerated in the diet. How much is tolerated must always be determined on an individual basis. Since lactose is often hidden in finished products and processed foods such as baked goods and sauces, those affected should always take a look at the list of ingredients and look for alternatives without lactose if necessary.
The following overview shows the lactose content of various foods. Depending on the individual affected by the intolerance, foods containing lactose should either be avoided altogether or only consumed in small amounts.
- High lactose content (over 4.5 g/100 g)
e.g. cow’s milk, goat’s milk, sheep’s milk, horse’s milk, whey, cocoa drinks, condensed milk and coffee cream - Average lactose content (1 to 4.5 g/100 g)
e.g. quark, cottage cheese, soured milk, soured cream, buttermilk - Almost lactose-free (less than 1 g/100 g)
e.g. butter, hard, semi-hard and soft cheese
Tips:
- It is best to eat dairy products with a meal containing protein or fat. This increases lactose tolerance and reduces symptoms.
- Capsules or tablets with lactase: they replace the missing lactase enzyme. The tablets are taken shortly before consuming foods containing lactose.
- Lactose-free dairy products can supplement a varied diet.
