Lactose Intolerance and Cow’s Milk Allergy

The terms lactose intolerance and cow’s milk allergy are very often used interchangeably in common language, although in fact they are two separate conditions. The immediate cause of the symptoms of both disorders is the consumption of milk and milk products, but each of them is caused by a different component in milk and a different reaction of the body. In this post I will try to explain the difference between lactose intolerance and allergy to cow’s milk protein. I will tell you about the symptoms that accompany these diseases, as well as the products that can be safely eaten in each case.

First of all, let’s list the different compounds in milk. It contains various groups of nutrients:

• carbohydrates, e.g. lactose (also known as milk sugar), which is made of two other sugars: galactose and glucose;
• proteins (including casein and whey proteins);
• as well as fats, vitamins, minerals, and water.

What Is Lactose Intolerance?

Lactose intolerance is the reduced ability or inability to break down lactose into galactose and glucose. The enzyme responsible for its breakdown is lactase. In the case of a deficiency of this enzyme, lactose under the influence of intestinal bacteria begins to ferment in the intestines, causing a number of symptoms.

The most common symptoms of lactose intolerance are flatulence, diarrhea, gas, abdominal pain, bloating, and nausea.

The degree of ailment is related to the amount of lactose consumed, and the tolerated dose of lactose is an individual matter. Symptoms of intolerance usually appear 30 minutes to several hours after consuming lactose-containing products. Lactose intolerance in Poland affects 1.5% of infants and children and 20-37% of adults.

There are three types of lactose intolerance:

• primary congenital – characterized by the innate inability of the body to produce the enzyme lactase; it usually appears in infants and children; it is the rarest type;
• primary late — during adolescence, some people have a decline in the production of lactase, which makes it difficult to digest dairy products; this reason affects approx. 70% of the world’s population;
• secondary — it is usually a temporary condition, it may be the result of inflammation of the stomach or intestines, surgery on the intestine, or a long dairy-free diet. 

What Is a Milk Protein Allergy?

An allergy is an abnormal reaction of the body to external factors, in which the immune system is involved. Allergy to milk (also called “protein intolerance”) is caused by the proteins in the milk that the body treats as an allergen. In response to contact with one of several dozen milk proteins, an abnormal reaction on the part of the immune system develops. An undesirable reaction consists in the production of antibodies against this protein. As a result of the increased immune response and the action of histamine, symptoms appear.

The reaction after exposure to the allergen can occur within minutes or even days. Symptoms vary, but usually relate to the digestive tract, skin and respiratory system. The most common symptoms include: flatulence, diarrhea, nausea, abdominal pain, rash, edema, itchy skin, atopic lesions, cough, shortness of breath, and even respiratory failure.

Allergy to milk proteins occurs mainly in infants and young children and usually resolves spontaneously with age. It is estimated that symptoms improve in 90% of children under 3 years of age. In the rest of the population, the symptoms are reduced, and the abnormal reaction is only caused by a higher dose of milk proteins.

The emergence of allergies early in life is primarily due to the child’s still immature immune system.

How to Recognize Intolerance and Allergy?

Both conditions should be diagnosed by a doctor. Self-diagnosis is difficult because in both cases the symptoms are similar.

In the case of lactose intolerance, it may be helpful to conduct a hydrogen breath test, stool pH tests or elimination tests consisting in discontinuing lactose-containing products for a certain period of time.

In the diagnosis of cow’s milk allergy examining medical history by a doctor, skin prick tests, and determination of total serum IgE levels play an important role.

Nutrition in Lactose Intolerance

People with a congenital inability to produce lactase should avoid products containing lactose. In other cases, it will not always be necessary to completely abandon dairy products. Current research suggests that a teenager or adult can take up to 12g of lactose per dose, which is about 240ml of milk (1 glass), without any symptoms. However, this is an individual matter and everyone should independently select the possible amount of lactose to eat based on the observation of their own body. However, no lactose dose has been identified for smaller lactose intolerant children.

The greatest amounts of lactose can be found in milk and whey. A smaller amount is found in yoghurt, kefir, cottage cheese and butter, while hard matured cheeses (such as Parmesan, cheddar, and gouda) contain very small amounts.

Lactose may also be present in many other foods that contain milk or raw materials derived from milk (e.g. powdered milk or whey), so it is always worth reading the label before buying a product. Remember that lactose is a sugar found in milk, so all goat and sheep milk products also contain some amounts. 

Nutrition in Allergy to Cow’s Milk Protein

Treatment of this type of allergy consists in introducing an elimination, dairy-free diet, i.e. temporary or permanent removal of milk and dairy products as well as products containing milk protein: whey, casein, or those products that contain even trace amounts of milk. In the case of diagnosed allergy to cow’s milk protein in an infant, it is necessary to eliminate milk and its products from the diet of the breastfeeding mother. Remember that it is the doctor who should decide whether to carry out any tests, apply an elimination diet or the length of the diet. An elimination diet carries the risk of deficiencies of some ingredients, e.g. calcium, so it is best to consult a dietitian.

Proper diagnosis and management of lactose intolerance or allergy to cow’s milk protein should always be consulted with a doctor. This will allow you to eliminate unwanted symptoms, as well as use a complete and balanced diet, despite the need to cut out some ingredients from the diet.

Bibliography:

1. Di Costanzo M, Berni Canani R. Lactose Intolerance: Common Misunderstandings. Annals of Nutrition and Metabolism. 2018;73:30–7.
2. Szilagyi A, Ishayek N. Lactose Intolerance, Dairy Avoidance, and Treatment Options. Nutrients. 2018 Dec 15;10(12):1994. 
3. Wąsik M, Nazimek K, Bryniarski K. Reakcje alergiczne na mleko krowie: patomechanizm, strategie diagnostyczne i terapeutyczne, możliwości indukcji tolerancji pokarmowej. Postepy Hig Med Dosw (online), 2018; 72: 339-348.