A sugar additive found in cream cakes, fruit juices and jams has fuelled the rise of a killer superbug, according to new research.
The study shows that the sugar - known as trehalose - is metabolized by the potentially deadly bacterium Clostridium difficile.
It suggests the common ingredient - which has been much-hyped in recent years as a 'healthy' alternative to sugar - is helping trigger epidemics across the world.
Trehalose, found in plants and fungi, is also used in dried and frozen foods, nutrition bars, fruit fillings, instant noodles and rice and white chocolate.
Trehalose has become a popular sugar alternative for bakers as studies found it to be less calorific with less danger to the heart and liver. But a new study says it could have another risk
It occurs naturally in small amounts in mushrooms, honey and seafood.
In recent years the UK, Europe and the US have seen a sharp increase in hyper-virulent strains that cause severe disease.
Symptoms include diarrhea, fever, loss of appetite, nausea and abdominal pain.
But the factors contributing to their emergence have been unclear - until now.
The study found two genetically distinct C. diff strains that have caused epidemics - known as RT027 and RT078 -have independently acquired unique mechanisms to break down low concentrations of trehalose.
Importantly it also showed this ability to metabolise the sugar was linked with disease severity in mice with a humanised form of C diff.
Bacterial strains can be analysed through differences in bits of DNA called ribosomal RNA - and assigned to particular 'ribotypes'.
Professor Robert Britton and colleagues used whole-genome sequencing and comparative analysis to discover the link.
It identifies the C diff strains and the widespread adoption and use of trehalose as a sugar additive in the human diet, and suggest that a harmless food additive may inadvertently select for pathogens.
Prof Britton, of Baylor College of Medicine in Houston, said: 'Clostridium difficile disease has recently increased to become a dominant pathogen in North America and Europe, although little is known about what has driven this emergence.
'Here we show that two epidemic ribotypes (RT027 and RT078) have acquired unique mechanisms to metabolise low concentrations of the disaccharide trehalose.'
Trehalose is a naturally-occurring sugar that is found in plants and insects.
It consists of two glucose molecules bound together.
The natural sugar has been approved by the US Food and Drug Administration for human consumption.
A study last year by scientists at Washington University School of Medicine found it prevents fructose from entering the liver.
The researchers found trehalose also triggers a