“No one is going and grabbing the broccoli,” said Alex DiFeliceantonio, associate director of the Center for Health Behaviors Research at the Fralin Biomedical Research Institute at VTC.
DiFeliceantonio and Ashley N. Gearhardt, a psychology professor at the University of Michigan, analyzed whether highly processed foods – such as sugary soft drinks, baked goods, chips, burgers and fries – can be considered addictive by comparing their properties to those of tobacco.
In an Nov. 9 opinion and debate article in the journal Addiction, they conclude that their addictive potential “may be a key factor contributing to the high public health costs associated with a food environment dominated by cheap, accessible and heavily marketed” highly processed foods.
Gearhardt and DiFeliceantonio applied three scientific criteria outlined in the 1988 Surgeon General’s report on tobacco products to highly processed foods. They found that highly processed foods share the addictive characteristics of tobacco because they cause compulsive use; have psychoactive, or mood-altering, effects on the brain; and are highly reinforcing. They added a fourth attribute, informed by an advanced understanding of behavior and the human brain, that the foods “trigger strong urges and cravings.”
“What we knew about the brain is 1988 is kind of laughable,” DiFeliceantonio said. “The idea that dopamine is important for these processes is actually relatively new.”
There is a consensus that all addictive substances increase dopamine release in the brain’s reward circuits. Gearhardt and DiFeliceantonio note that when delivered orally, highly processed foods and nicotine increase dopamine in the same part of the brain at a similar magnitude — 150 percent to 200 percent over baseline for highly-processed foods compared to 150 percent to 250 percent for nicotine.
The hallmarks of highly processed foods are that they lack fiber; include a significant amount of added sugar, salt and fat; and their nutrition labels include a long list of often unrecognizable ingredients. They have become a growing part of the American diet as manufacturers have produced inexpensive, convenient foods with a long shelf life.
“The ability of highly processed foods to rapidly delivery unnaturally high doses of refined carbohydrates and fat appear key to their addictive potential,” DiFeliceantonio said.
“Minimally processed, nourishing foods, such as fruits and vegetables, do not meet these addiction criteria,” Gearhardt noted. Tobacco manufacturers and the general public were slow to accept that tobacco was addictive and harmful. “This delayed the implementation of effective strategies to address this public health crisis.”
DiFeliceantonio, who is an assistant professor with the Fralin Biomedical Research Institute and Virginia Tech’s Department of Human Nutrition, Foods, and Exercise, anticipates strong debate over whether such foods can be called addictive.
“There is no agreed upon amount by which a drug has to increase dopamine for us to consider it addictive,” DiFeliceantonio said. “Even though we know a lot more about the neurochemical signature of a lot of these processes, we don’t actually use them to define addiction.”
So how does this help improve human health?
“Making a mistake and classifying these substances as addictive when they’re not causes less harm than the other way around,” DiFeliceantonio said. She hopes the debate gets more people thinking and talking about the addictive qualities of highly processed foods and their impact on human health, and that it drives demand for more research.
“I’m willing to see data on either side, but the truth is we need to run better experiments rigorously designed to test these ideas,” she said.