"Caution" warranted if consuming artificial sweeteners

Troy Brown

July 10, 2013

West Lafayette, IN - Consumption of noncaloric, artificially sweetened beverages (ASBs) is associated with an increased risk for obesity, type 2 diabetes, metabolic syndrome, and cardiovascular disease, according to an opinion article by Dr Susan E Swithers (Purdue University, West Lafayette, IN) published online July 10, 2013 in Trends in Endocrinology & Metabolism.

"This somewhat counterintuitive result may reflect negative consequences of interfering with learned relationships between sweet tastes and typical postingestive outcomes, which may result in impaired ability to compensate for energy provided when caloric sweeteners are consumed," Swithers writes.

The prospective studies Swithers reviewed found an elevated risk for weight gain and obesity, metabolic syndrome, type 2 diabetes, coronary heart disease, and hypertension in those who consumed ASBs. No decreased risk for weight gain or increased body fat percentage was associated with ASB intake.

It was often difficult to compare the magnitude of increased risk with that of participants who consumed sugar-sweetened beverages (SSBs), in part because of differences in intake.

Participants who regularly consumed ASBs tended to have higher baseline body-mass indexes (BMIs) compared with participants who did not, but some models that adjusted for that difference still found an increased risk. Studies that separately assessed risk among those who were not overweight or obese at baseline found that the risks of becoming overweight or obese, developing type 2 diabetes, and experiencing vascular events were increased even when considering baseline BMIs.

Hormones, brain response altered

Swithers reviewed two interventional studies. The first found that children of normal weight who consume ASBs may have decreased weight gain compared with those who consume SSBs. The study did not compare children who consume ASBs with those who consume unsweetened beverages. In the second study, overweight and obese adults who substituted water or ASBs for SSBs had no greater weight loss at six months than an attentional control group. ASB intake was not associated with improved fasting glucose, but water intake was.

Brain responses are altered in those who consume artificial sweeteners compared with those who consume caloric sweeteners. In imaging studies of the human brain, sucrose activates dopaminergic midbrain areas involved with reward, but sucralose does not. Sucralose also reduces activation in other pathways related to taste when compared with sucrose.

In addition, studies in humans have found that the release of hormones and markers of postprandial glucose homeostasis typically seen does not occur after ingestion of artificial sweeteners.

Studies that combined artificial sweeteners in various ways with nutrients found that "artificial sweeteners may not augment nutrient-dependent release of insulin or the incretins in the same way that caloric sugars do," Swithers writes.

"Current findings suggest that caution about the overall sweetening of the diet is warranted, regardless of whether the sweetener provides energy directly or not," Swithers concludes.

Dr Frank Hu (Harvard School of Public Health, Boston, MA) commented on the article in an email interview.

"Overall, I think the jury is still out regarding whether drinking diet sodas instead of SSBs is truly related to obesity and [cardiovascular-disease] outcomes, in part because of the complex methodological problems in studying the effects of diet sodas in epidemiological studies. Small, short-term, [randomized controlled trials] do show that drinking diet sodas instead of SSBs reduces weight gain or induces more weight loss in controlled settings," Hu said.

"Because [the] intense sweetness of ASBs may condition people toward greater preference for sweets and may enhance appetite and because of the possibility that some consumers of diet soda may use this as a rationale for consuming other higher-calorie foods, caution is needed for recommending regular consumption of ASBs," Hu explained.

"In [the] short term, ASBs are preferable to the use of SSBs. For those who want to kick the habit of drinking sugary soda, diet soda may be the beverage equivalent of a nicotine patch: it can be used in small amounts, for a short time. For most people, plain water and unsweetened coffee or tea are healthier alternatives to either SSBs or ASBs," Hu concluded.

This research was supported by the National Institutes of Health . Disclosure information was not provided for Swithers. Hu has disclosed no relevant financial relationships.

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