The previous post mentioned some of the authorities who have a hard time justifying a scientific basis for the intrinsic addictiveness of foodstuffs. But always, there is just enough evidence to make the possibility tantalizingly attractive to many parties, for various reasons.
The title “The Biology Behind ‘Food Addiction‘” puts the loaded term in quotation marks, and discusses the activation of reward systems:
[T]he activity of the endogenous, natural, opioid system is influenced by ingestion of palatable diets, and […] changes in the activity of the system in turn affect behavior, feeding and, perhaps, diet preference.
Similarly, both dopamine release and dopamine receptor levels are affected by palatable diets. From this it is apparent that dysfunction of these systems has the potential to contribute to overeating and the pathophysiology of obesity.
The authors explain that brain reward systems evolve to reinforce natural behaviors that are advantageous to the individual. Addictive substances connect up with the same reward systems and subvert them, making their existence a liability rather than an asset. Still, this does not constitute convincing proof that foods or food components should be considered addictive in the same sense as, for instance, cocaine.
The same organization published in 2016 a multi-faceted report on their investigations into “clinical, basic, and epidemiological research exploring the neurobiological interface between food intake, reward and stress.” They found slender evidence to support the idea that food or isolated ingredients can cause addiction in the same sense as addictive drugs.
Sugar probably presents the strongest case for thinking of a food as addictive, but the notion of sugar addiction left this team unmoved for a number of reasons:
[W]e find little evidence to support “sugar addiction.” Indeed, in animal studies we found divergence regarding brain pathways involved in reward behavior for a sweet reward from those that specifically modulate addiction-related behaviors.
The authors went on to speak of the importance of interactions between the brain’s reward pathways and the regulatory circuitry in the body that pertains to feeding. They mention the poor understanding of the neural substrate that makes this all happen, or not happen, as the case may be. It is known that the hormones leptin and ghrelin signal for other things to occur, but lining up their actions with the origin and persistence of eating disorders was nowhere near complete enough to be positive about anything.
There is a reasonable expectation that this interaction is key to the addictive properties of specific food components and the emergence of disordered eating. But it is poorly understood how food components affect the reward circuitry, and to what extent hormones provide the link between ingestion of food and reward, and we have a poor understanding of the addictive properties of individual food components.
Your responses and feedback are welcome!
Source: “The Biology Behind ‘Food Addiction'”, Cordis.europa.eu, undated
Source: “Final Report Summary — NEUROFAST (The Integrated Neurobiology of Food Intake, Addiction and Stress.),” Cordis.europa.eu, January 2016
Image by Robin Stickel on Unsplash