Researchers say that low-calorie sweeteners - often found in diet sodas - may boost the formation of fat.

Principal study investigator Dr. Sabyasachi Sen, of George Washington University in Washington, D.C., and colleagues reached their findings by analyzing the effects of sucralose on stem cells derived from human fat tissue, as well as on abdominal fat samples.

The researchers recently presented their findings at ENDO 2017 - the 99th annual meeting of the Endocrine Society, held in Orlando, FL.

Sucralose is a zero-calorie, artificial sweetener that is up to 650 times sweeter than sugar. It is used as a sugar substitute in a wide variety of products, including diet sodas, table-top sweeteners (such as Splenda), baking mixes, gum, breakfast cereals, and even salad dressings.

Given the widely documented health implications of sugar consumption, an increasing number of people are turning to products containing sucralose and other artificial sweeteners, with the view that they are better for health.

"However, there is increasing scientific evidence that these sweeteners promote metabolic dysfunction," notes Dr. Sen.

For their study, the researchers sought to gain a better understanding of how low-calorie sweeteners affect the body's metabolism at a cellular level.

Sucralose led to buildup of fat droplets in fat-derived stem cells

Firstly, Dr. Sen and team applied sucralose to stem cells derived from human fat tissue.

The stem cells were exposed to the artificial sweetener for a total of 12 days at a dose of 0.2 millimolars - a dose comparable to the blood concentration of people who drink around four cans of diet soda daily.

The researchers found that the stem cells showed an increase in the expression of genes that are indicators of fat production and inflammation. Additionally, the stem cells demonstrated an increase in the accumulation of fat droplets, especially when exposed to a higher sucralose dose of 1 millimolar.

Next, the researchers took biopsies of abdominal fat from eight adults, of whom four were obese and four were a healthy weight. All adults reported consuming low-calorie sweeteners, primarily sucralose and aspartame.

Abdominal fat samples were then compared with samples taken from adults who did not consume low-calorie sweeteners.

The team found that adults who consumed low-calorie sweeteners not only showed an increase in the transportation of glucose into cells, but they also demonstrated an overexpression of genes associated with fat production.

Furthermore, the researchers identified an overexpression of sweet taste receptors that was up to 2.5 times higher among the fat samples of adults who consumed low-calorie sweeteners. Such overexpression may play a part in the transportation of glucose into cells. From there, glucose is absorbed into the bloodstream.

The effects of low-calorie sweeteners were strongest among adults who were obese, the team notes.

Findings a concern for people with pre-existing high blood glucose

Taken together, Dr. Sen and colleagues say that their findings indicate that low-calorie sweeteners may dysregulate the metabolism in a way that boosts the formation of fat.

The increase in transportation of glucose into cells may be of particular concern for adults who have prediabetes or diabetes, the researchers note, as these individuals already have higher levels of blood glucose.

Still, the researchers caution that further studies are required in larger samples of people before any concrete conclusions can be made about the effects of low-calorie sweeteners on metabolism.

"However, from our study, we believe that low-calorie sweeteners promote additional fat formation by allowing more glucose to enter the cells, and promotes inflammation, which may be more detrimental in obese individuals."   Dr. Sabyasachi Sen