Addictiveness of Junk Food
November 2/New York/Bloomberg -- A growing body of medical research at leading universities and government laboratories suggests that processed foods and sugary drinks are not simply unhealthy. They can hijack the brain in ways that resemble addictions to cocaine, nicotine and other drugs.
“The data is so overwhelming the field has to accept it,” said Nora Volkow, director of the National Institute on Drug Abuse. “We are finding tremendous overlap between drugs in the brain and food in the brain.”
The idea that food may be addictive was barely on scientists’ radar a decade ago. Now the field is heating up. Lab studies have found sugary drinks and fatty foods can produce addictive behavior in animals. Brain scans of obese people and compulsive eaters, meanwhile, reveal disturbances in brain reward circuits similar to those experienced by drug abusers.
Some 28 scientific studies and papers on food addiction have been published this year, according to a National Library of Medicine database. As the evidence expands, the science of addiction could become a game changer for the $1 trillion food and beverage industries.
If fatty foods and snacks and drinks sweetened with sugar and high-fructose corn syrup are proven to be addictive, food companies may face the most drawn-out consumer safety battle since the anti-smoking movement took on the tobacco industry a generation ago.
“This could change the legal landscape,” said Kelly Brownell, director of Yale University’s Rudd Center for Food Policy & Obesity and a proponent of anti-obesity regulation. “People knew for a long time cigarettes were killing people, but it was only later they learned about nicotine and the intentional manipulation of it.”
Food company executives and lobbyists are quick to counter that nothing has been proven, that nothing is wrong with what PepsiCo chief executive officer Indra Nooyi calls “fun-for-you” foods, if eaten in moderation. In fact, the companies say they are making big strides toward offering consumers a wide range of healthier snacking options.
No one disputes that obesity is a fast growing global problem. In the U.S., a third of adults and 17% of teens and children are obese, and those numbers are increasing. Across the globe, from Latin America, to Europe to Pacific Island nations, obesity rates are also climbing.
The cost to society is enormous. A 2009 study of 900,000 people, published in The Lancet, found that moderate obesity reduces life expectancy by two to four years, while severe obesity shortens life expectancy by as much as 10 years. Obesity has been shown to boost the risk of heart disease, diabetes, some cancers, osteoarthritis, sleep apnea and stroke, according to the Centers for Disease Control and Prevention. The costs of treating illness associated with obesity were estimated at $147 billion in 2008, according to a 2009 study in Health Affairs.
Sugars and fats, of course, have always been present in the human diet, and human bodies are programmed to crave them. What has changed is modern processing that creates food with concentrated levels of sugars, unhealthy fats and refined flour, without redeeming levels of fiber or nutrients, obesity experts said. Consumption of large quantities of those processed foods may be changing the way the brain is wired.
Those changes look a lot like addiction to some experts. Addiction “is a loaded term, but there are aspects of the modern diet that can elicit behavior that resembles addiction,” said David Ludwig, a Harvard researcher and director of the New Balance Foundation Obesity Prevention Center at Children’s Hospital Boston. Highly processed foods may cause rapid spikes and declines in blood sugar, increasing cravings, his research has found.
Education, diets and drugs to treat obesity have proven largely ineffective, and the new science of obesity may explain why, proponents say. Constant stimulation with tasty, calorie-laden foods may desensitize the brain’s circuitry, leading people to consume greater quantities of junk food to maintain a constant state of pleasure.
In one 2010 study, scientists at Scripps Research Institute in Jupiter, Fla., fed rats an array of fatty and sugary products including Hormel Foods Corp. bacon, Sara Lee Corp. pound cake, The Cheesecake Factory Inc. cheesecake and Pillsbury Co. Creamy Supreme cake frosting. The study measured activity in regions of the brain involved in registering reward and pleasure through electrodes implanted in the rats.
The rats that had access to these foods for one hour a day started binge eating, even when more nutritious food was available all day long. Other groups of rats that had access to the sweets and fatty foods for 18-23 hours per day became obese, Paul Kenny, the Scripps scientist heading the study wrote in the journal Nature Neuroscience. The results produced the same brain pattern that occurs with escalating intake of cocaine, he wrote.
“To see food do the same thing was mind-boggling,” Kenny later said in an interview.
Researchers are finding that damage to the brain’s reward centers may occur when people eat excessive quantities of food.
In one 2010 study conducted by researchers at the University of Texas in Austin and the Oregon Research Institute, a nonprofit group that studies human behavior, 26 overweight young women were given magnetic resonance imaging scans as they got sips of a milkshake made with Haagen-Dazs ice cream and Hershey Co.’s chocolate syrup.
The same women got repeat MRI scans six months later. Those who had gained weight showed reduced activity in the striatum, a region of the brain that registers reward, when they sipped milkshakes the second time, according to the study results, published last year in the Journal of Neuroscience.
“A career of overeating causes blunted reward receipt, and this is exactly what you see with chronic drug abuse,” said Eric Stice, a researcher at the Oregon Research Institute.
Scientists studying food addiction have had to overcome skepticism, even from their peers. In the late 1990s, NIDA’s Volkow, then a drug addiction researcher at Brookhaven National Laboratory on Long Island, applied for a National Institutes of Health grant to scan obese people to see whether their brain reward centers were affected. Her grant proposal was turned down.
“I couldn’t get it funded,” she said in an interview. “The response was, 'There is no evidence that food produces addictive-like behaviors in the brain.'”
Volkow, working with Brookhaven researcher Gene-Jack Wang, cobbled together funding from another government agency to conduct a study using a brain scanning device capable of measuring chemical activity inside the body using radioactive tracers.
Researchers were able to map dopamine receptor levels in the brains of 10 obese volunteers. Dopamine is a chemical produced in the brain that signals reward. Natural boosters of dopamine include exercise and sexual activity, but drugs such as cocaine and heroin also stimulate the chemical in large quantities.
In drug abusers, brain receptors that receive the dopamine signal may become unresponsive with increased drug usage, causing drug abusers to steadily increase their dosage in search of the same high. The Brookhaven study found that the obese people also had lowered levels of dopamine receptors compared with a lean control group.
The same year, psychologists at Princeton University began studying whether lab rats could become addicted to a 10% solution of sugar water, about the same percentage of sugar contained in most soft drinks.
An occasional drink caused no problems for the lab animals. Yet the researchers found dramatic effects when the rats were allowed to drink sugar-water every day. Over time they drank “more and more and more” while eating less of their usual diet, said Nicole Avena, who began the work as a graduate student at Princeton and is now a neuroscientist at the University of Florida.
The animals also showed withdrawal symptoms, including anxiety, shakes and tremors, when the effect of the sugar was blocked with a drug. The scientists, moreover, were able to determine changes in the levels of dopamine in the brain, similar to those seen in animals on addictive drugs.
“We consistently found that the changes we were observing in the rats binging on sugar were like what we would see if the animals were addicted to drugs,” said Avena, who for years worked closely with the late Princeton psychologist, Bartley Hoebel, who died this year.
While the animals did not become obese on sugar water alone, they became overweight when Avena and her colleagues offered them water sweetened with high-fructose corn syrup.
A 2007 French experiment stunned researchers when it showed that rats prefer water sweetened with saccharine or sugar to hits of cocaine -- exactly the opposite of what existing dogma would have suggested.
“It was a big surprise,” said Serge Ahmed, a neuroscientist who led the research for the French National Research Council at the University of Bordeaux.
Yale’s Brownell helped organize one of the first conferences on food addiction in 2007. Since then, a protégé, Ashley Gearhardt, devised a 25-question survey to help researchers spot people with eating habits that resemble addictive behavior.
She and her colleagues used magnetic resonance imaging to examine brain activity of women scoring high on the survey. Pictures of milkshakes lit up the same brain regions that become hyperactive in alcoholics anticipating a drink, according to results published in the Archives of General Psychiatry in April.
Food addiction research may reinvigorate the search for effective obesity drugs, said Mark Gold, who chairs the psychiatry department at the University of Florida in Gainesville. Gold said the treatments he is working on seek to alter food preferences without suppressing overall appetite.
“We are trying to develop treatments that interfere with pathological food preferences,” he said. “Let’s say you are addicted to ice cream; you might come up with a treatment that blocked your interest in ice cream, but doesn’t affect your interest in meat.”
In related work, Shire Plc, a Dublin-based drugmaker, is testing its Vyvanse hyperactivity drug in patients with binge-eating problems.
Not everyone is convinced. Swansea University psychologist David Benton recently published a 16-page rebuttal to sugar addiction studies. The paper, partly funded by the World Sugar Research Organization, which includes Atlanta-based Coca-Cola argues food does not produce the same kind of intense dopamine release seen with drugs and that blocking certain brain receptors does not produce withdrawal symptoms in binge-eaters as it does in drug abusers.
Still unknown is whether the science of food addition has begun to change the thinking among food and beverage companies. About 80% of PepsiCo’s marketing budget, for instance, is directed toward pushing salty snacks and sodas. Although companies are quick to point to their healthier offerings, their top executives are constantly called upon to reassure investors those sales of snack foods and sodas are showing steady growth.
“We want to see profit growth and revenue growth,” said Tim Hoyle, director of research at Haverford Trust Co. in Radnor, Pa., an investor in PepsiCo. “The health foods are good for headlines, but when it gets down to it, the growth drivers are the comfort foods, the Tostitos and the Pepsi-Cola.”
Little wonder that the food industry is pushing hard on the idea that the best way to get a handle on obesity is through voluntary measures and by offering healthier choices. The same tactic worked for awhile, decades ago, for the tobacco industry, which deflected attention from the health risks and addictive nature of cigarettes with “low tar and nicotine” marketing.
Food industry lobbyists do not buy that argument -- or even the idea that food addiction may exist. Said Richard Adamson, a pharmacologist and consultant for the American Beverage Association, “I have never heard of anyone robbing a bank to get money to buy a candy bar or ice cream or pop.”
From the November 2, 2011, Prepared Foods' Daily News.