Processed carbohydrates are addictive, brain study suggests
People may joke they're addicted to desserts, but new brain imaging research shows there may be some truth to the statement.
Researchers have found eating highly-processed carbohydrates like cakes, cookies and chips could affect pleasure centers in the brain, leading to serious cravings that might cause people to overeat.
"Beyond reward and craving, this part of the brain is also linked to substance abuse and dependence, which raises the question as to whether certain foods might be addictive," study author Dr. David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital, said in a press release.
Our brains consist of a complex network of pathways and regions that control for all our bodily functions. Chemical messengers called neurotransmitters allow signals to pass from one nerve cell to the next to aid in these functions.
One neurotransmitter, dopamine, plays a major role in the brain's reward pathways. For example, the brain gets flooded with dopamine whenpeople take addictive drugs including cocaine and nicotine.
To find out how food intake was regulated by the dopamine-reward pathway, Ludwig and his colleagues recruited 12 overweight or obese men between the ages of 18 and 35 years old. On two occasions, they were fed milkshakes that were almost identical except one had a high-glycemic index and one was low-glycemic.
The glycemic index measures how fast blood sugar levels rise after eating that item. High-glycemic carbohydrates get digested rapidly, and include white bread, pasta, rice and baked goods, WebMD notes. Low-glycemic carbs are digested much slower, and include fruits, vegetables, unproessed whole grains and legumes.
Four hours after the meals, they were given fMRI brain scans that measured activity of these networks and pathways.
Participants who drank the high-glycemic milkshakes saw their blood sugar levels surge, only to sharply crash four hours later. When their blood sugar dropped, not only did they feel excessive hunger, but the fMRIs showed "intense" activation in the nucleus accumbens, a region of the brain involved in addiction.
The researchers pointed out previous studies comparing eating vegetables or high-calorie cheesecakes also showed different brain reactions. But, this study showed that when calories and sweetness are equal, glycemic index could still trigger brain changes that might lead to overeating.
"These findings suggest that limiting high-glycemic index carbohydrates like white bread and potatoes could help obese individuals reduce cravings and control the urge to overeat," said Ludwig.
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Commenting on the study, Dr. Christoph Buettner, an associate professor of neuroscience at the Mount Sinai Medical Center in New York City, told Everyday Health, "Food activates similar areas in the brain as drugs do, that is already accepted." Buettner, who was not involved in the research, added, "The strength of this study is that it shows that the kind of diet you eat can influence this."
The new research was published June 26 in the American Journal of Clinical Nutrition.
