People with irritable bowel syndrome who have genetic defects in carbohydrate digestion respond better to specific dietary interventions, a study has shown.
Variations in human carbohydrate-active enzymes in people with IBS mean they have a better response to a carbohydrate-reduced diet.
This could lead to genetic markers being used to predict which patients would benefit from personalised, specific diets.
Up to 10% of people globally suffer from IBS, with symptoms including bloating, diarrhoea, constipation and abdominal pain.
Treatment of the condition is difficult as there are big variations in symptoms and responses to drug or dietary treatment.
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However, excluding or reducing certain foods, particularly carbohydrates, had found to be effective for some people.
The area of science which looks at how the combination of genes and nutrition impacts our health is called nutrigenetics.
Experts in this field have highlighted how DNA changes alter the way we process food in the body. The best example of this is lactose intolerance. In this case, the digestion of dairy products is hampered by a loss of function in the lactase enzyme.
This latest study, led by Professor Mauro D’Amato from LUM University in Italy, has highlighted how variations in human carbohydrate-active enzymes (hCAZymes) may similarly affect how people with IBS respond to a carbohydrate-reduced diet, and how they may benefit from it.
Dr D’Amato said: “These findings suggest that genetic variations in hCAZyme enzymes, which play a key role in digesting carbohydrates, could become critical markers for designing personalised dietary treatments for IBS.
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“The ability to predict which patients respond best to a carbohydrate-reduced diet has the potential to strongly impact IBS management, leading to better adherence and improved outcomes.”
A group of 250 people with IBS were involved in the study, which compared two different treatments – one was a diet low in fermentable carbohydrates, the other was the antispasmodic medication otilonium bromide.
A key finding was that out of the 196 people on the low carbohydrates diet, greater improvement was seen in those individuals with the defective hCAZyme genes, compared to non-carriers.
This improvement was particularly strong in the individuals with diarrhoea-predominant IBS. Importantly, this difference was not seen in the patients taking the medication, which highlights the importance of genetic predisposition when it comes to the effectiveness of dietary intervention.
Also involved in the study was Dr Maura Corsetti, from the University of Nottingham, who said: “These data need to be further validated by future studies. If confirmed, this approach opens the way to personalised dietary and treatment strategies.”
