Although she subscribes to a healthy lifestyle, 90-year-old Helen Nelson confesses her downfall to her doctor. "I'm a chocoholic," she admits with a wink.
Her sweet indulgence never fuelled an eating disorder, caused obesity or hatched a chronic disease such as diabetes. Rather, Nelson has remained exceptionally active and has even spent her golden years helping people who struggle with poor health.
Nevertheless, researchers at the Princeton Neuroscience Institute in New Jersey might peg Nelson and others who crave confections as potentially "sugar addicted." The researchers recently studied rat behaviour to reveal that bingeing on sugar might have neuron-chemical roots. The study suggests that sugar intake can trigger the brain in similar ways to classic drugs that are abused, such as cocaine, nicotine and morphine.
In the food deprivation experiment, researchers offered food and a soft drink-like sucrose solution to hungry rats. The hungry animals responded by bingeing on the sugar water and eventually interacted with the sugar solution in all the ways that indicate addiction vulnerability. For instance, they fell into a cycle of bingeing, suffering withdrawal symptoms and craving- key stages of dependency that can lead to addiction, according to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders. Interestingly, the rats' disordered eating also changed their neurochemistry within a month. Sugar surges flooded their brains with dopamine, a feel-good chemical associated with motivation, in an area called the nucleus accumbens. Bingeing caused the rats' brains to adapt to the dopamine overload by producing fewer dopamine receptors and more opiod receptors—a phenomena that resembles brain activity in the presence of classically-addictive substances. Both dopamine and opiod receptor systems control the act of liking something and desiring it.
At this stage of the experiment, rats suffered withdrawal symptoms when they were cut off from the sugar solution and allowed only food and water. In fact, their teeth chattered and they appeared too anxious to enjoy exploring the maze in their cage.
The researchers also noted that the animals, after learning to binge in the controlled lab environment, worked harder than ever to get the sweet drink when it was reintroduced to them. Such a response suggests craving and relapsing, other key behaviours related to addiction.
With this study completed, lead researcher Bart Hoebel said the Princeton team's work may prompt more brain-imaging studies that compare sugar addiction and drug addiction in humans. The study may also give researchers in eating-disorder clinics more reason to suspect sugar addiction in patients, especially those diagnosed with binge-driven bulimia.
Dr Warren Peters, director at the Loma Linda University Centre for Health Promotion in California, considers the study extremely important. "Those of us who treat obesity know [clients]... who will tell you that they're addicted to starch and sugar," he says.
Peters considers the findings particularly relevant for vegetarians. "If [people] decrease protein intake, then they're attracted to a lot more starch and sugar," he says. "It's not across the board but there is a subset of people [addicted to] starch and sugar."
Peters points out that even if you're a vegetarian, you still have to be careful to make healthy food choices. An Adventist health study found that of those participants who follow a lactoovo diet (a vegetarian diet that includes egg and dairy products), 47 per cent of the women and 52 per cent of the men were overweight or obese (based on a body mass index of 25 or greater). Part of the explanation for this, says Peters, could be related to sugar addiction.
Dr Richard Johnson, chief of the Division of Renal Diseases and Hypertension at the University of Colorado at Denver, US, has also conducted research about the addictive nature of sugar. His research indicates that high-sugar diets may hijack leptin, a hormone associated with appetite and body-weight regulation in humans.
"[Those suspected of sugar addiction] lose their normal signalling to the brain that tells them to stop eating," says Dr Johnson. This loss of signalling is a disturbing component of sugar bingeing.
Helen Nelson, the self-described chocoholic, may not perfectly fit the profile of a sugar addict. While some people binge on sweets, she nibbles on chocolate. Still, recent findings show that for some, sugar is bittersweet.
" 'Driven' is probably too strong a word. But it's not that far off," said Peters of sugar addiction. "This research will be very positive in opening the doors to treatment."