For rats, the most alluring substance isn’t alcohol, heroin, or cocaine: it’s not a drug at all, in fact, it’s an artificial sweetener called saccharin. What’s saccharin? Saccharin is a non-caloric sugar substitute that has been used in many low-calorie foods and diet drinks (remember TaB?) for over 100 years. And rodents find it irresistible.
Researchers at University Bordeaux, France have discovered that rats will do just about anything for saccharin –even stop taking cocaine! In a series of experiments, laboratory rats were trained to press two levers; one lever gave the rats a small amount of saccharin water to drink, and the other delivered a hit of cocaine, I.V. Researchers were surprised to find that when given the choice between saccharin and cocaine, virtually all rats chose saccharin. With an increase in the amount of work required to get saccharin, the rats still chose the artificial sweetener over cocaine. Furthermore, rats “addicted” to cocaine chose to drink saccharin. The researchers went on to investigate the effect that cocaine and saccharin have on dopamine, a neurotransmitter released during rewarding experiences. The surge of dopamine release when the rats took cocaine was much greater than when they consumed saccharin, which suggests that the amount of dopamine in the brain is not directly tied to the perceived hedonic value of a food or drug (contrary to most theories).
So rats prefer intensely sweet food over cocaine, but what about humans? Saccharin is sweet and rewarding to us, although it has a subtle, less-than-desirable aftertaste. Similar to rats, we have an intense drive to satisfy our sweet tooth. But unlike our furry friends, we’ve become accustomed to obtaining comfort foods, not with levers but dollar bills. The food and beverage industry rakes in billions every year by marketing high fat, high carbohydrate products. These sugary, salty, fatty foods promote compulsive overeating comparable to drug addicts’ wanting more…and more…and more…and more drug. Severe health risks associated with comfort food ingredients (trans fats, e.g.) have turned the Food and Drug Administration’s head. In fact, some of these ingredients are now banned in parts of the US. Other compounds, like sugar and other artificial sweeteners, may also become regulated soon. Given that humans remain hooked on sweets, it’s only a matter of time until comfort foods become controlled substances like drugs of abuse are currently.
Lenoir M, Serre F, Cantin L, & Ahmed SH (2007). Intense sweetness surpasses cocaine reward. PloS one, 2 (1) PMID: 17668074
Cantin L, Lenoir M, Augier E, Vanhille N, Dubreucq S, Serre F, Vouillac C, & Ahmed SH (2010). Cocaine is low on the value ladder of rats: possible evidence for resilience to addiction. PloS one, 5 (7) PMID: 20676364