According to a study
presented by Francesco Leri, an addiction expert and Associate Professor of Neuroscience and Applied Cognitive Science at the University of Guelph, at the 2013 meeting of the Canadian Association of Neuroscience
, food addiction could partly explain the current global obesity epidemic.
According to the "Food Addiction" hypothesis that has been proposed by some experts, one could become addicted to taste enhanced food just as one could become addicted to addictive drugs such as cocaine.
To test the hypothesis
, Dr. Leri carried out a study on the response of rats to foods containing very high concentrations high-fructose corn syrup (HFCS).
In the experiments, rats were fed diets containing different levels of HFCS. They were then taught to press a lever which controlled how much syrup they received. The researchers found that rats responded to diets containing large amounts of HFCS in the same way that cocaine addicts respond when addicted to the drug. The more concentrated the syrup, the harder the rats worked at pressing the lever to obtain the taste enhanced food.
According to the researchers, the findings of their study suggest that foods with high levels of HFCS have the same addictive properties as cocaine and could partly explain the global obesity epidemic.
Leri concluded: "We have evidence in laboratory animals of a shared vulnerability to develop preferences for sweet foods and for cocaine. As you increase the percentage (of HFCS), the animals work harder and harder for each infusion. There is now convincing neurobiological and behavioral evidence indicating that addiction to food is possible."
The findings suggest that increased availability of taste enhanced foods could explain the high global incidence of obesity. However, experts believe that availability is not enough to explain why, given the same levels of availability, some people are obese and others are not. According to Dr. Leri and his colleagues, one of the factors predisposing to obesity could be individual differences in vulnerability to addiction.
According to a former head of the FDA, David Kessler
, eating sugar is "highly pleasurable. It gives you this momentary bliss. When you're eating food that is highly hedonic, it sort of takes over your brain."
Previous studies on cocaine use have found that although many try the drug, only a small percentage become addicted. Leri and his colleagues concluded that the same principle applies to high HFCS foods: different individuals have different levels of vulnerability to food addiction which explains why some people are obese and why some are not, in spite of the widespread availability of HFCS enhanced foods.
High-fructose corn syrup can be found in practically all fast-foods. Research has implicated the product not only in obesity but also in other diseases such as diabetes. HFCS became widely available in 1970s after it was discovered in the 1950s. It is found in processed foods such as bread, pizza, meat, donut, chocolate bars, soda, cereals, ketchup, soup, tinned tuna, mayonnaise and yougurt.
Apart from making food more palatable, it is also used to increase the shell-life of processed food products.
A 2008 study
by Professor Bart Hoebel and his colleagues at Princeton University's Department of Psychology and the Princeton Neuroscience Institute, found that rats fed on high sugar diets showed withdrawal symptoms when sugar was withdrawn from their diet. They exhibited withdrawal symptoms of stress, nervousness and anxiety, similar to those found in people addicted to drugs such as nicotine and morphine.
: "If bingeing on sugar is really a form of addiction, there should be long-lasting effects in the brains of sugar addicts. Craving and relapse are critical components of addiction, and we have been able to demonstrate these behaviors in sugar-bingeing rats in a number of ways."
Leri and his colleagues investigated the behavioral, chemical and neurobiological changes induced by consumption of HFCS enhanced foods in the bodies and brains of rats. He said: "We are not rats, but our children do not think too much about the impact of sweets on their brain and behavior. There is now convincing neurobiological and behavioral evidence indicating that addiction to food is possible. Our primary objective is to discover biological predictors of vulnerability to develop excessive consumption of high fructose corn syrup."
According to Leri and his colleagues, their findings could lead to novel pharmacological intervention for obese individuals that could help them make wiser dietary choices.
The researchers proposed that educating the public about the consequences of their dietary choices could be an effective strategy for combating the global obesity epidemic.
According to WHO
, there is a worldwide epidemic of obesity, which it terms "globesity." The distribution of the incidence is not limited to affluent industrialized societies. It occurs also in less developed economies. WHO estimates that the global incidence of obesity has more than doubled since 1980 with more than 1.4 billion people classified as overweight in 2008 and 500 million of overweight people classified as obese.
Obesity poses major health risks. The incidence of diabetes, cardiovascular diseases, hypertension, stroke and certain forms of cancer is higher among obese people.
The US Food and Drug Administration places a legal limit of 55 percent
on the fructose content of HFCS. But studies have shown that fructose levels in popular soda brands are often higher than the legal limit. The Corn Refiners Association who produce HFCS have revealed that they have been producing a version of HFCS with 90 percent fructose levels for decades, although the product has never been tested for safety or approved by FDA.