Food intolerances: lactose, gluten, fructose and casein

What is food intolerance and how does it occur?

Food intolerances are difficult to diagnose because symptoms can vary greatly and may not appear immediately or may develop over 48 hours. However, identifying them can be important because by eating mindfully, you can significantly improve your well-being and avoid potential negative effects on your body.

Common symptoms of food intolerance include:

• diarrhea,
• flatulence,
• skin rashes,
• headache,
• nausea,
• fatigue,
• stomach ache,
• runny nose,
• reflux,
• skin redness.

The causes of food intolerance can be different. 

Some food intolerances/allergies can be caused by::

• Immune-mediated
  • food allergy 
  • celiac disease
• Non-immune mediated
  • lack of an enzyme needed to digest certain foods, e.g. lactase in the case of lactose intolerance or the enzyme aldolase B in the case of fructose intolerance
  • other chemical compounds, e.g. caffeine, amines (especially histamine)
  • mechanism of origin unknown
    • food additives, e.g. certain food colours, preservatives, flavourings, antioxidants
    • irritable bowel syndrome
    • psychological factors
• Toxic reactions

Sometimes the causes of food intolerance remain unclear. 

Food intolerance and food allergy 

Food intolerance and food allergy are not the same condition, although some symptoms may be similar. An allergy is a hypersensitivity reaction that results in an unusual immune response to food. Common allergens include eggs, milk, nuts, fish, shellfish, wheat, soy, and sesame. In the case of a food allergy, even a small amount of the allergen can cause a variety of severe or life-threatening symptoms. For example, anaphylactic shock can be fatal. A blood sample is taken from a vein to test for food allergies, and in the case of allergies, IgE antibodies may be found in the sample.

In contrast, food intolerances often cause digestive and respiratory disorders, skin lesions and are generally less serious. The severity of the manifestation of a food intolerance is also related to the amount eaten. This means that if a food intolerance occurs, it may not always be necessary to completely exclude eating a specific food, but it is primarily worth monitoring your personal well-being and finding an appropriate tolerable amount.

In this post we will discuss food allergy For more information on the topic and allergens, see: From the nutrition website of the Estonian Institute for Health Development.

Food intolerance statistics

Food intolerance is common and its incidence seems to be increasing. It is difficult to give exact figures because sometimes food intolerance occurs, but sometimes the person suspects it, but the food intolerance has not been identified. However, studies have been conducted on this topic and we can point out some observations:

• It is estimated that approximately 20% of the world's population has a food intolerance. 
• LactPartial intolerance occurs least in Northern Europe (10%) and most in southern countries (even up to 90%). Lactose intolerance occurs in Estonia about 23–32% of adults. 
• It is estimated that approximately 30% from the West and Africa and about 10% from the Asian population.
• It has been discovered that spread of celiac disease has been increasing steadily and in Estonia it affects nearly 31% of the population.

Common food intolerances and their symptoms

We describe some of the most common food intolerances and their symptoms. It is worth knowing that the symptoms of food intolerances and their severity can vary from person to person.

Lactose intolerance

Lactose intolerance is not milk intolerance – lactose intolerance, or milk sugar intolerance, is caused by a deficiency of the enzyme lactase, which prevents the breakdown of lactose. As a result, consuming foods containing lactose causes discomfort. Symptoms of lactose intolerance may include discomfort, bloating, diarrhea, and abdominal pain.

In case of lactose intolerance, it is still necessary and possible to consume dairy products to obtain enough calcium. In many cases, a person can eat dairy products with a low lactose content (e.g. kefir, yogurt, cheese) or they can be replaced with lactose-free dairy products. It is important that the menu is well thought out and consists of foods that can also be eaten in case of lactose intolerance, which will result in a complete and varied diet. Calcium can also be obtained from, for example, nuts, seeds, herbs, beans, dark green plant parts and soy products. On the importance and bioavailability of calcium We have also written in more detail on our blog.

You can read more in depth lactose intolerance from the information sheet.

Casein intolerance

In case of casein or milk protein intolerance, the absorption of milk protein is impaired, which is why all foods containing dairy products must be avoided, including lactose-free dairy products, fermented dairy products, and non-dairy products that contain dairy products, such as casein or caseinate, hydrolysers (casein, milk protein, whey), lactalbumin, lactose or lactulose, skimmed milk powder, and milk powder.

Symptoms of casein intolerance may include skin rash, shortness of breath, vomiting, diarrhea, stomach cramps, and runny nose.

Celiac disease and non-celiac gluten intolerance

Often used interchangeably celiac disease, gluten intolerance, grain intolerance, gluten sensitivity, sometimes too wheat intolerance or wheat allergy, but it can be a different condition. Gluten intolerance can occur in both the autoimmune disease celiac disease and non-celiac gluten sensitivity. 

In celiac disease, gluten damages the lining of the small intestine, resulting in impaired nutrient absorption and nutrient deficiencies. In this case, symptoms of gluten intolerance may include fatigue, nausea, vomiting, diarrhea, abdominal pain, weight loss, iron deficiency, Vitamin B12 or folic acid deficiency, skin rash, joint problems, tooth enamel problems (cyanosis), neurological problems, depression. In non-celiac gluten sensitivity, symptoms may resemble celiac disease, but blood tests and small bowel examination do not reveal symptoms suggestive of celiac disease. In wheat allergy, symptoms occur immediately or within a few hours after eating foods containing wheat.

If you are diagnosed with celiac disease, you must follow a lifelong gluten-free diet, meaning you must avoid wheat, rye, barley (often also oats) and products containing these grains. You should carefully read the ingredients on packages to avoid consuming hidden gluten. If you are gluten intolerant, it is important to know what you can eat and which foods are not suitable for a gluten-free diet. Estonian Celiac Society The website has a comprehensive list of allowed and prohibited foods. A gluten-free diet can alleviate symptoms. Non-celiac gluten sensitivity can also benefit from a gluten-free diet, but there is still a lot of ignorance and uncertainty about this condition. It is currently known that this type of gluten sensitivity does not cause intestinal damage and is not as serious a condition as celiac disease.

Celiac disease You can read more about it in the information sheet.

Fructose intolerance

In the case of fruit sugar, or fructose intolerance, eating fruit, as well as other sweets and honey, causes digestive discomfort. The most common symptoms of fructose intolerance may be abdominal pain, bloating, constipation and diarrhea.

Fructose intolerance can be congenital or genetic or acquired during life or secondary. It is important to be aware of the fructose content of foods. Usually, if you have fructose intolerance, you can consume foods containing a small amount of fructose, and by experimenting, you can discover your personal fructose tolerance limit, which is worth considering.

Pharmacological intolerance

Pharmacological intolerance can occur when consuming food containing substances with pharmacological properties. The most common causes of intolerance are caffeine (in coffee, tea, chocolate, cocoa) and histamine (in processed meat products, canned fish, cheese, citrus fruits, bananas, pineapples, strawberries, tomatoes, nuts, spinach, cocoa, etc.).

Food intolerance due to additives

The causes of food intolerance caused by additives are still unclear, but it is known that children and people with asthma are more sensitive to them. There are also many safe additives. Finding information about additives can be helpful e-subjects search engineYou can read about the harmfulness of additives from the food additives table.

Food intolerance testing options and treatment

Since the mechanisms of food intolerance are different, there is no single universal food intolerance test that would identify all possible food intolerances. There are different methods for testing for food intolerance. 

Lactose intolerance can be diagnosed by a lactose tolerance test (LTT) or hydrogen breath test. The LTT test is performed in the morning without eating or drinking beforehand. The patient is given lactose dissolved in water to drink and the change in their blood sugar level is monitored. In the hydrogen breath test, the patient must fast for 24 hours and is given a lactose solution the next morning. If the concentration of hydrogen in the exhaled air is high, lactose intolerance is likely present. In cases of lactose and fructose intolerance, genetic analysis can be performed.

Celiac disease is diagnosed based on blood tests (assuming the patient has eaten gluten), and if the blood test result is positive, a small bowel study is performed to detect intestinal damage. In the case of gluten sensitivity, celiac disease is often ruled out first, and if it is not present, a gluten-free diet can be tried and its effect on well-being assessed.

There is no diagnostic tool to detect additive and pharmacological intolerance. This is also complicated by the fact that the tolerance limit is individual.

The most common methods used for diagnosis are keeping a food diary, assessing the effect of food on well-being, and if a food intolerance is suspected, removing the food from the menu (often for 2-4 weeks). If symptoms do not improve within this time, then the suspected allergy or intolerance is unlikely. 

In addition to the above-mentioned methods of detecting food intolerance, there may be additional options, so if you suspect that you or your child has a food intolerance, it is worth consulting with your doctor or nutritionist about food intolerance testing and treatment options. Research is constantly being conducted in this area to better understand the mechanisms of unwanted reactions to food, the reliability of food intolerance tests and possible treatment methods. Currently, there is still uncertainty and sometimes even conflicting views among different doctors and nutritionists. 

To alleviate symptoms caused by food intolerance, it is often necessary to avoid specific foods or ingredients. To avoid nutritional deficiencies caused by diet and to ensure a complete and varied diet, it may be useful to consult a nutritionist or dietician. During the consultation, it is possible to improve your knowledge of nutrients and receive advice on how to replace foods that cause food intolerances so that you do not develop nutritional deficiencies in the body.