A sugary syrup widely used in processed foods like biscuits can cause behavioural changes similar to the effects of cocaine, according to new research.
High-fructose corn syrup (HFCS), used as a sweetener and to improve the appearance of food after baking, was tested by a scientist investigating "food addiction".
The substance, which has previously been linked to rising rates of type-2 diabetes, was found to induce behavioural changes similar to the Class A drug in tests on laboratory rats.
Professor Francesco Leri, who carried out the research, said it suggested there was an addictive quality to foods that are high in sugar which could explain, at least partly, the current global obesity epidemic.
"We have evidence in laboratory animals of a shared vulnerability to develop preferences for sweet foods and for cocaine," he said, adding: "We are not rats, but our children do not think too much about the impact of sweets on their brain and behaviour. There is now convincing neurobiological and behavioural evidence indicating that addiction to food is possible."
Prof Leri, from the University of Guelph, Canada, said the food addiction hypothesis suggests people can be addicted to food just as one is addicted to drugs of abuse. He studied the response of rats to foods containing unnaturally high concentrations of sugar, fats and taste enhancers, such as HFCS and foods like biscuits.
The research, presented at the 2013 Canadian Neuroscience Meeting, argues that just as some people become addicted to cocaine after taking it and others did not, the same is true with foods like HFCS.
Those behind the food addiction hypothesis argue the simple fact that sugar-rich foods are more widely available does not explain why some people are obese and others are not. They believe vulnerability to addiction, as in cocaine, could be an important factor.
HFCS has a greater proportion of fructose sugar than sucrose, which contains an equal amount of glucose.
Last November, a University of Oxford-led study found that countries that use large amounts of HFCS have higher rates of diabetes than those that consume little. Of the countries studied, the US had far and away the greatest consumption per head of HFCS, amounting to 25 kilograms per year. UK consumption was very low at less than 0.5 kilograms per person per year.