British study links carb breakdown gene in saliva to obesity

British researchers have discovered a link between a gene that breaks down carbohydrates and obesity, which may pave the way for more effective, individually tailored diets for people wanting to lose weight.

Researchers at King's College London and Imperial College London found that people with fewer copies of a gene responsible for carbohydrate breakdown may be at higher risk of obesity. The findings, published in Nature Genetics, suggest that dietary advice may need to focus more on a person's digestive system, based on whether they have the genetic predisposition and necessary enzymes to digest different foods.

The salivary amylase gene plays a key role in breaking down carbohydrates in the mouth at the start of the digestion process. The new study suggests that people with fewer copies of the AMY1 gene have lower levels of this enzyme and so have more difficulty breaking down carbohydrates than those with more copies.

Previous research has found a genetic link between obesity and food behaviours and appetite, but the discovery highlights a genetic link between metabolism and obesity.

The study suggests that people's bodies may react differently to the same type and amount of food, leading to weight gain in some and not in others.

The effect of the genetic difference found in the latest study appears to be a much stronger link than in any of those found before, say the researchers.