Is there an allergy to lactose? Allergy vs. intolerance
Lactose, also known as milk sugar, is a disaccharide made up of glucose and galactose molecules. Lactose intolerance occurs when the enzyme – lactase – is missing or its activity is reduced in the small intestine. This prevents the breakdown of the disaccharide into simple sugars. As a result, undegraded lactose is not absorbed in the intestine. Instead, it ferments, causing unpleasant symptoms, particularly from the gastrointestinal tract [1].
Cow’s milk protein allergy, on the other hand, is a reaction of the immune system to proteins present in milk, such as casein or beta-lactoglobulin. In an allergy, the body misidentifies the proteins as a threat and triggers an immune response. This leads to a range of symptoms – from mild, such as rashes, itching and hives, to severe, such as diarrhoea and difficulty breathing. The most serious consequence of food allergy is anaphylactic shock, which can be life-threatening [2].
How do you distinguish between lactose intolerance and cow’s milk protein allergy?
The main differences between intolerance and allergy are their mechanism and the components that trigger the body’s reaction. In lactose intolerance, the immune system is not involved and symptoms are caused by an inability to digest the sugar. An allergy, on the other hand, is an immune reaction triggered by an incorrect recognition of the milk protein as a pathogen. Consequently, a lactose allergy does not exist. Lactose is a sugar – not a protein. And it is mainly proteins that cause allergic reactions.
Intolerance can also be distinguished from allergy on the basis of the spectrum of symptoms. Intolerance most often manifests itself with gastrointestinal complaints, while in the case of allergy there are also symptoms from other systems. These include, for example, shortness of breath, rashes, itching, swelling and even anaphylactic shock.
Different diagnostic methods are used to distinguish between these conditions. Lactose intolerance is diagnosed on the basis of a hydrogen breath test, lactose load test or stool pH analysis. Allergies, on the other hand, are diagnosed by skin tests, blood levels of IgE antibodies and food challenge tests.
Treatment also includes various methods. In intolerance, lactose is restricted or eliminated from the diet. Lactose-free products may also be consumed and enzyme preparations containing lactase may be used.
Allergy to cow’s milk proteins usually requires the exclusion of milk and milk products from the diet. However, if an allergic person is found to tolerate a small amount of dairy products, they should not be completely eliminated from the diet. Additionally, some people only react to selected types of milk proteins. They may therefore consume dairy products that do not contain them. The individual types of protein lose their allergenic properties after heat treatment. This is why some allergic persons do not experience any discomfort after eating dairy products that have been baked or boiled, for example.
In the course of an allergy, the development of tolerance to milk proteins is periodically tested, particularly in children. However, oral provocation tests should be carried out under medical supervision. In severe cases of allergic reactions, it may be necessary to reach for antihistamines and even epinephrine (adrenaline) [1,2,3].
These differences indicate that lactose intolerance and cow’s milk protein allergy are two separate disease entities. Their names should therefore not be used interchangeably [3].
Lactose intolerance – symptoms in adults and children
Lactose intolerance can cause a wide variety of complaints in both adults and children. Most symptoms occur on the gastrointestinal side [1,2,4,5,6,7].
In adults, these include:
- abdominal pain,
- nausea,
- diarrhoea,
- flatulence,
- belching,
- excessive gas production,
- burping, bubbling, overflowing,
- a feeling of fullness,
- discomfort in the abdominal area [1,2,7].
In children the characteristic features are:
- colic (especially in infants),
- diarrhoea,
- hard and bloated abdomen,
- nausea,
- vomiting [4,5].
In addition, children and infants sometimes become restless and tearful by experiencing unpleasant discomforts. It is also worth emphasising that they may have difficulty gaining weight [3,4,5].
Typically, symptoms of lactose intolerance appear between 30 minutes and 2 hours after consuming dairy products. The intensity of discomfort is an individual issue. It may vary between individuals depending on the amount of lactose consumed, the degree of lactase deficiency and the level of enzyme activity [1,6,7].
Lactose intolerance – skin symptoms
With lactose intolerance, skin symptoms are rare. The complaints are mostly related to digestive problems and the fermentation of lactose in the intestines. Skin symptoms such as rashes, redness and itching are more characteristic of an allergy to cow’s milk proteins. The allergy can also manifest itself in hives, atopic dermatitis or swelling of the skin. Allergic skin reactions occurring after consumption of milk or milk products can be immediate or delayed [2,3].
Lactose intolerance in infants – the poo matters
Symptoms of lactose intolerance in infants often include digestive problems such as diarrhoea, bloating and colic. A change in the appearance of the stool is also a characteristic symptom. The stool of an infant with lactose intolerance may be watery, frothy and have a sour smell. Attention should also be paid to the frequency of bowel movements, which may be much more frequent than usual.
If it is noticed that the infant has frequent diarrhoea, bloating, is restless, irritable or has a hard and tense abdomen, it is worth consulting a doctor. An early reaction and consultation with a specialist is essential so that they can refer the parent and child for appropriate tests to confirm lactose intolerance. This will make it possible to introduce an appropriate diet for the toddler, to improve their wellbeing and to ensure their proper development [4,5].
Lactose intolerance – diagnostic tests
The first step in diagnosing lactose intolerance is a detailed medical history. During the medical history, the doctor asks about the symptoms, their severity and the time of occurrence after the consumption of milk and dairy products. This enables the doctor to establish a cause-and-effect relationship between the food consumed and the complaints and to plan further diagnostic steps [2].
One of the main diagnostic tests for lactose intolerance is the hydrogen breath test. It involves ingesting a lactose solution and then measuring the hydrogen concentration in the exhaled air. A high hydrogen level indicates lactose fermentation in the gut, suggesting lactose intolerance. Another test is the oral lactose loading test. The person being tested consumes a lactose solution and then their blood glucose level is measured. If the glucose level does not rise, this may indicate a disorder of lactose digestion in the body.
In children and infants, stool pH analysis is often used. An acidic reaction may suggest fermentation of undigested lactose. In younger patients, hydrogen breath tests are also performed, but adapted to their age.
Once the intolerance is initially confirmed, an elimination-provocation trial is carried out. This involves completely eliminating lactose from the diet for several weeks. Observing whether the symptoms subside and then return after consumption of milk or dairy products confirms the diagnosis. In such a trial, a food diary is a helpful tool. It should include information on the food consumed and the type and timing of symptoms [2,3,7].
How to treat lactose intolerance?
Treatment of lactose intolerance is mainly based on dietary modification. Its basic principle is to exclude or limit foods containing lactose. Due to the individual tolerance of milk sugar, for some people it is sufficient to simply avoid foods with the highest lactose content, such as milk and cream. For others, even a small intake of dairy can trigger symptoms.
Lactose-free dairy products are available in the shops as an alternative for those with lactose intolerance. For those who do not want to give up milk and milk products, enzyme preparations containing lactase are also available. Taken before meals, they help in the digestion of lactose [2,3,7].
People who exclude milk and dairy products from their diet should ensure an adequate intake of calcium and vitamin D, as dairy products are a rich source of these. In order to prevent deficiencies, it is advisable to reach for other products rich in these components or, following a doctor’s recommendation, dietary supplements.
In addition, it is important to watch out for hidden sources of lactose, especially in highly processed foods. Some medicines may also contain lactose as a filler. It is therefore important to read food labels and drug formulations [8].
Recognising lactose intolerance and adjusting your diet can significantly improve your quality of life. Consultation with a doctor or dietician can be helpful in balancing the menu appropriately. With proper diagnosis and treatment, troublesome symptoms can be quickly eliminated [8].
