A large study of children and teens finds that having asthma or food allergies at age 12 increases the chances of developing teenage irritable bowel syndrome.

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Irritable bowel syndrome (IBS) affects more than 1 in 10 people, but not everyone who experiences these symptoms consults a doctor. IBS can affect adolescents, teens, and adults.

According to an older study, some experts estimate that about 14% of teens experience the disorder. However, few recent studies have investigated prevalence in younger people.

Doctors do not fully understand what causes IBS, but new research investigating IBS in 16-year-olds suggests a strong link with prior and concurrent asthma and food allergies.

Teens having IBS at 16 were almost twice as likely to have had asthma at age 12, and close to half of them had experienced food hypersensitivity at that age.

“This knowledge could open up for developing new treatment methods for adolescent IBS, targeting processes of low grade inflammation seen in these allergy-related diseases,” says lead author Dr. Jessica Sjölund.

The researchers conducted their study at the University of Gothenburg and the Karolinska Institute in Stockholm, Sweden. They presented it at the United European Gastroenterology’s UEG Week Virtual 2020 conference in October 2020.

IBS is not life threatening, but the discomfort it causes is often disruptive, especially in teens and young females. This is because IBS can compound changes the body is already going through.

Stomach or abdominal pain is the main symptom of IBS.

People with IBS may experience cramping, bloating, and gas and will have at least two of the following symptoms:

  • Pain or discomfort with bowel movements.
  • Changes to their bowel movement schedule, with either an increase or decrease in frequency.
  • Changes to stools due to constipation where stools become too hard to pass easily, or diarrhea, which has the opposite effect.

IBS is not a disease; it is a functional disorder in which the bowels do not behave normally. IBS does not cause physiological damage, making it difficult for doctors to make a straightforward diagnosis.

Some teens may be reluctant to draw attention to such symptoms. According to co-author Hans Törnblom, who is one of Europe’s leading IBS experts:

“Even though functional gastrointestinal disorders are common, many patients are, unfortunately, negatively stigmatized and labeled. The fact that many IBS sufferers do not seek medical advice should be of great concern. As well as dedicating resources to improve the physical elements of living with disorders like IBS, care and investment must be committed to providing psychological and emotional support for patients, so they are comfortable seeking medical advice.”

The study involved tracking the health of 2,770 children from birth until they reached 16 years of age through questionnaires. The parents completed the questionnaires with and on behalf of their children until the participants were 16 when they answered the questions themselves.

The questionnaires asked about the presence of asthma, allergic rhinitis, eczema, and food hypersensitivity when the children were 1, 2, 4, 8, 12, and 16 years old. When the participants were 16 years old, they answered questions derived from the Rome III Questionnaire on Pediatric Gastrointestinal Symptoms.

According to their answers, the researchers assigned the participants into three groupings: IBS, functional abdominal pain, and functional dyspepsia.

Of the participants, 11.2% of those with IBS had also had asthma at the age of 12, while just 6.7% of those without IBS had asthma at that age. While 29.2% of individuals who did not have IBS at age 16 reported having had food hypersensitivity at 12, that figure rose to 40.7% for those with IBS.

The analysis also found associations between having asthma, food hypersensitivity, and eczema at age 16 with a higher risk of developing IBS at that age.

The research may help to identify the causes of IBS. “We knew,” says Sjölund, “that allergy and immune dysregulation had been suggested to play a role in the development of IBS, but previous studies on allergy-related diseases and IBS are contradictory.”

Now, however, she says, “The associations found in this large study suggest there’s a shared pathophysiology between common allergy-related diseases and adolescent irritable bowel syndrome.”