Lactose, gluten: how do you know if you have a food intolerance? – 05/14/2022

If for most people eating is a pleasant sensation, for others, eating certain foods means feeling sick and having several gastrointestinal discomforts, as is the case of those who have some intolerance.

“Food intolerance is an adverse reaction of the body that occurs mainly in the digestive system, due to the difficulty in digesting a certain food”, explains Karina Gama, clinical nutritionist at Instituto Dante Pazzanese of Cardiology. According to her, the discomfort can occur either by the absence or defect in the action of enzymes that carry out the “breaking” of some components of the food as by substances present in the food that cause a difficult digestion.

Among food intolerances, lactose intolerance is the most common, and occurs when there is a deficiency of the lactase enzyme, responsible for the digestion of lactose, the sugar present in milk and derivatives, such as cheeses and yogurts.

But there is also intolerance to gluten (or non-celiac gluten sensitivity), intolerance to fructose (sugar found in fruits, some vegetables and cereals and in processed products), to sucrose (table sugar) and to undigested carbohydrates, which are later fermented by intestinal bacteria and which are also known as fodmap (derived from milk, fruits, cereals, legumes and some sweeteners).

Anyone can have food intolerance and the factors that predispose it depend on the individual’s conditions, such as genetics, health status, immunological status, or the food itself, such as allergenic potential, conservation and amount ingested, according to Hélcio Maranhão, gastroenterologist and pediatric nutrologist, professor at the Department of Pediatrics at UFRN (Federal University of Rio Grande do Norte).

In the case of those who have intolerance, the symptoms can start soon after or a while after eating the food, and last for hours.

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How to identify if you have an intolerance to any food?

Symptoms and signs may vary, but are generally related to the digestive system: cramping or abdominal pain, gastric bloating, distention, borborygmus (belly noises), nausea, regurgitation, flatulence, constipation and even diarrhea. Systemic symptoms such as irritability, fatigue, migraine, hives and joint pain may also be present, according to Auzelivia Rêgo Falcão, gastroenterologist, professor of the discipline of gastrointestinal and coloproctological system diseases at the Department of Integrated Medicine at UFRN.

Symptoms can start soon after or some time after eating food, and last for hours. Relief usually occurs after complete fermentation of the undigested components by intestinal bacteria or elimination of the substance through the feces.

But it is important to make it clear that just feeling bad after eating food does not constitute food intolerance. “That’s because there are other digestive diseases that can cause similar symptoms, including food poisoning”, says Falcão.

In order to suspect the condition, the continuity and persistence of symptoms is necessary when consuming the food at different times. “Making a food diary describing the symptoms and the foods eaten that day can help”, adds the gastroenterologist.

If the person suspects that they have intolerance, it is recommended that they suspend the food in question. “This measure is expected to favor the reduction and resolution of symptoms. After a few weeks, she can go back to consuming the food in order to see if such symptoms return. If so, there is a high probability that she has the condition” , says Maranhao.

If the manifestation of clinical symptoms are persistent, the doctor or nutritionist can perform a detailed evaluation to confirm the diagnosis. This includes a medical history investigation, medications or supplements being used, lifestyle habits, bowel function, and dietary habits.

What tests can be done?

Some laboratory and specific tests can help in the diagnosis. Among them, there is the oral tolerance test, which helps to identify lactose intolerance, for example. This test consists of offering the person the substance being investigated, on an empty stomach, and after 30, 60, 90 and 120 minutes, collecting the blood to see if there has been an increase in fasting blood glucose by at least 20 mg/dl, as a result of digestion of the substance studied. If the blood glucose elevation is lower, it is found that digestion was incomplete and there was no adequate absorption.

The expired hydrogen test uses the same principle as the oral tolerance test, but instead of evaluating the change in blood glucose, the patient blows a device that measures the amount of expired hydrogen in the fasting state after the ingestion of the investigated standard solution, in intervals ranging from 2 to 4 hours.

“In the patient with intolerance, the undigested and absorbed substance is fermented by the bacteria present in the final portion of the intestine, forming hydrogen. Therefore, the increased detection of hydrogen in the breath reflects the inability to digest and absorb the substance properly” , explains Karina Gama, master in food science.

There are still other tests that can be used, such as the stool acidity test, which is usually used in babies or children, bowel biopsy and genetic tests, more indicated when traditional tests are inconclusive. For non-celiac gluten sensitivity, tests are performed to investigate celiac disease.

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If there is suspicion, the ideal is to look for a doctor or nutritionist and do tests, so that the person does not make unnecessary dietary restrictions.

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Intolerance and allergy are different

Tests to confirm the diagnosis are important, even so as not to confuse food intolerance with food allergy, which are different conditions.

As already explained, food intolerance consists of the lack of the enzyme responsible for the digestion of a certain food, causing difficulty in its absorption. It is a condition that generates more local symptoms, linked to the gastrointestinal tract.

Allergies, on the other hand, because they are immunological phenomena, may have general reactions or compromise different devices, such as the skin and respiratory system, in addition to the gastrointestinal system.

How is the treatment?

According to the experts consulted in the report, the treatment of food intolerance must be individualized and is based on reducing or excluding the foods that cause the problem.

Some people can tolerate small amounts of the product, but this limit is individual. In lactose intolerance, preference should be given to lactose-free or low-lactose products. There is also the option of using the enzyme lactase, in the form of tablets or powder to be diluted in liquids, before or together with foods containing lactose. This may lessen the occurrence of symptoms, but may not be entirely effective.

Nutritionist Gama reinforces that “all intolerance must be properly diagnosed by a health professional so that unnecessary restrictions on food are not carried out”.

Sources: Auzelivia Trench Hawkgastroenterologist, professor of diseases of the gastrointestinal system and coloproctological from the Department of Integrated Medicine at UFRN (Federal University of Rio Grande do Norte), also works at the Onofre Lopes University Hospital (HUOL/UFRN); Helcio Maranhãopediatric gastroenterologist and nutrologist, full professor at the Department of Pediatrics at UFRN, secretary of the Department of Nutrology at the Brazilian Society of Pediatrics; Karina GamaClinical nutritionist at Instituto Dante Pazzanese in Cardiology, and a master’s degree in food science from the Faculty of Pharmaceutical Sciences at USP (University of São Paulo).

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