The expert review and opinion piece published in Trends in Endocrinology & Metabolism suggests that while consumers and public health officials should be 'rightfully concerned' about the consequences of consuming high levels of sugar, for example from sugar-sweetened beverages - intakes of diet drinks and other non-caloric, artificially sweetened foods and beverages may not be the healthy choice to manage weight that they appear.
Indeed, building on recommendations to slash the intake of added sugar products such as sugar sweetened beverages, Professor Susan Swithers of Purdue University, USA, warned that public health concerns and warnings may also need to be expanded "to advocate limiting the intake of all sweeteners, including no-calorie sweeteners and so-called diet soft drinks."
"Although it seems like common sense that diet sodas would not be problematic, that doesn't appear to be the case," she commented.
"Findings from a variety of studies show that routine consumption of diet sodas, even one per day, can be connected to higher likelihood of heart disease, stroke, diabetes, metabolic syndrome and high blood pressure, in addition to contributing to weight gain."
In her opinion piece (which can be found here) Swithers suggests that while consumption of sugar-sweetened drinks and foods has been linked to obesity, type 2 diabetes, and metabolic syndrome - several recent studies in humans have also suggested that consumption of artificially sweetened beverages and foods are associated with obesity, type 2 diabetes, and metabolic syndrome in addition to possibly increasing the risk of cardiovascular disease.
Sweet desires
Moreover, the research noted that people who regularly consume artificial sweeteners have been shown to have altered activation patterns in the brain's pleasure centres in response to sweet taste - suggesting that such products may not satisfy the desire for sweets.
Similarly, studies in mice and rats have shown that consumption of noncaloric sweeteners dampens physiological responses to sweet taste, causing the animals to overindulge in calorie-rich, sweet-tasting food and pack on extra pounds, she said.
"These studies suggest that telling people to drink diet sodas could backfire as a public health message," Swithers argued. "The current public health message to limit the intake of sugars needs to be expanded to limit intake of all sweeteners, not just sugars."
One sided?
Dr Haley Curtis Stevens, of the Calorie Control Council, whose members include manufacturers and end users of low and reduced calorie sweeteners and other ingredient, commented that Swithers opinion piece "ignores the large body of robust scientific research that demonstrates the safety and benefits of low-calorie sweeteners."
"This study adds no new data to the literature, as it is an "opinion piece," rather than a peer reviewed study," she added - noting that the piece itself has several flaws and limitations, including the fact that Swithers only presents studies that supported her opinion and ignored the rest of the scientific literature.
"For example, the author cited two studies that found a link between the use of low-calorie sweeteners and weight gain, but ignored the over a dozen studies that demonstrated that low-calorie sweeteners could be useful tools for lowering and/or maintaining body weight."
Curtis Stevens added that many of the studies cited to support the opinions in the piece were performed in rodents, not humans.
"There are differences between rodent and human bodily processes and it cannot be assumed that the reported results of these studies would apply in humans."
Swithers noted that expanding studies from animal models to humans is a major challenge, with many researchers trying to answer questions about how diet drinks affect humans.
"Studies that show specific mechanisms and metabolic causes are from animal models," explained Swithers. "In human studies, researchers can only see correlations and not identify specific causes."
She also added that putting together a well-designed study in humans is become a major challenge because of how ubiquitous sweeteners have become in the mainstream diet.