People have chewed coca leaves for at least 8,000 years as a mild stimulant without any evidence of addiction, but when certain components are isolated and concentrated into cocaine, we’ve got a problem. The same may be true of sugar—people don’t tend to binge on bananas. The isolation of sugar from the whole food may be the reason we’re more likely to supersize soda than sweet potatoes, or why we’re less likely to eat too much corn on the cob, but can’t seem to get enough high fructose corn syrup.
The overconsumption of sugar-sweetened diets has often been compared to drug addiction. However, until very recently this parallel was based more on anecdotal evidence than on solid scientific grounds. But now we have PET scans, imaging technology that can measure brain activity. It all started with a publication from the Institute of Clinical Physiology that showed decreased dopamine sensitivity in obese individuals. The heavier they were, the less responsive to dopamine they appeared to be. We see the same reduction in sensitivity in cocaine addicts and alcoholics, which “would suggest that a reduction in dopamine receptors is associated with addictive behavior irrespective of whether it is due to food or to addictive drugs, as seen in substance abusers.”
Dopamine is considered the neurotransmitter primarily involved in the pleasure and reward center of our brain, helping to motivate our drive for things like food, water and sex—all necessary for the perpetuation of our species. It was healthy and adaptive for our primate brains to drive us to eat that banana when there wasn’t much food around. But now that fruit is in fruit loop form, this adaptation has “become a dangerous liability.” The original Coca-Cola formulation actually included coca leaf, but now, perhaps, its sugar content may be the addictive stand-in.
What about artificial sweeteners? They could still have adverse effects regardless of their individual chemistry. See my 3-part series:
What about fatty foods like meat? Does fat have addictive qualities as well? Good question! Check out my video Are Fatty Foods Addictive?
-Michael Greger, M.D.
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