Study reveals what artificial sweeteners do to the human body

A recent medical study involving 120 people showed that artificial sweeteners used in foods and drinks may alter the balance of bacteria in the gut and affect how the body handles glucose.

The study was carried out by researchers in the Elinav lab at the Weizmann Institute, who divided participants into six groups. Four of those groups received one of four sweeteners — saccharin, sucralose, aspartame and stevia — while the other two groups received no sweeteners.

After two weeks, the researchers found that the four sweeteners produced changes in the composition and function of the gut microbiome, the community of microorganisms that live in the intestines and play an important role in bodily functions. The nature of those changes varied by sweetener type and between individuals.

The results also showed that saccharin and sucralose significantly affected the body’s ability to tolerate and metabolize glucose, changes the researchers said could be associated with metabolic diseases such as type 2 diabetes and obesity.

The researchers emphasized that the long-term health consequences of these changes remain unclear, and that the study’s findings do not mean that sugar is better than artificial sweeteners. They stressed the need for longer studies to fully understand the effects of sweeteners on health.

Professor Tim Spector, on the "Zoe Science and Nutrition" podcast, said saccharin and sucralose could, over time, increase the risk of developing diabetes. He noted that all four sweeteners affected the gut microbiome and caused varying degrees of what is known as "microbial imbalance" (dysbiosis).

He explained that the body’s response to sweeteners differs from person to person, adding that the presence of several different sweeteners in a single product makes them difficult to avoid.

Spector said studies indicate sweeteners are not inert as previously thought; the body absorbs them and they can interact with it in ways that are hard to predict.

In contrast, the UK National Health Service (NHS) says that approved sweeteners undergo rigorous safety assessments before being allowed for use, and considers them a safe and acceptable alternative to sugar when consumed within permitted limits.

The NHS notes that scientific evidence on the effects of sweeteners on health and weight is mixed. Some short-term studies have found that replacing sugary drinks with calorie-free sweetened drinks can reduce calorie intake and help limit weight gain, while long-term studies have produced conflicting results.

Johns Hopkins School of Medicine says research into the possible health risks of sweeteners is ongoing, and that human studies generally indicate they are safe when used within acceptable daily intake levels.

Regarding sugar, the school says it is not harmful by nature — the body needs glucose for energy — but the problem is excessive intake of added sugar, which is present in large amounts in many processed foods (as opposed to natural sugars found in fruit). Excess added sugar may be linked to high blood sugar, insulin resistance, obesity, tooth decay and a higher risk of type 2 diabetes.

While the study indicates short-term effects of some sweeteners on the microbiome and the body’s glucose response, determining their long-term health effects will require further research.