Your sweet tooth could depend on your ability to digest sugar

Your sweet tooth could depend on your ability to digest sugar

If you can’t digest sugar well, there’s a good chance you don’t like it.

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Published: November 13, 2024 at 12:01 am

When we have cravings, there are those who reach for the ice cream and those who seek something saltier. Either way, you probably have a tough time imagining how the other camp live. How could anyone not like chocolate?

Well, a new study may provide an answer. It turns out some people who don’t like sugary foods could have a genetic defect in their DNA that makes it harder for them to digest sucrose (the chemical name for sugar).



Genetic defects in sucrose digestion are often associated with irritable bowel syndrome. Yet the new research, published in the journal Gastroenterology, now suggests a defect affecting the sucrase-isomaltase (SI) gene can also influence how much we enjoy eating sugary foods in the first place.

To find this out, the research team led by the University of Nottingham began by studying mice. These mice lacked the SI gene, and the scientists observed that they had a much lower preference for the intake of sucrose.

They then turned to humans, studying 6,000 people from Greenland and almost 135,000 from the UK whose data is stored in the UK BioBank. They discovered that Greenlandic participants with a fully dysfunctional SI gene, meaning they were completely unable to digest sugary foods, consumed a lot less sugar than those with a functional SI gene.

Meanwhile, in the UK, those with only a partially functional SI gene – almost 10 per cent of the cohort – had a much lower preference for sugary foods than those with a functional SI gene.

So, could your lack of sweet tooth be down to a genetic defect? Not necessarily.

“If you don’t like sweet foods, it is possible that you have reduced SI function, but is more likely that other factors with larger effect sizes drive the reduced sweet liking,” Dr Mette Andersen, co-author of the study and assistant professor at the University of Copenhagen in Denmark, told BBC Science Focus.

Nevertheless, excessive sugar consumption is a big driver of obesity and type 2 diabetes rates. The scientists behind the study think that they could help to reduce sugar intake by developing new drugs that target the SI gene and improve digestive health.


About our expert

Dr Metter Andersen is an assistant professor at the Novo Nordisk Foundation Centre for Basic Metabolic Research at the University of Copenhagen, in Denmark.

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