Artificial, or zero-calorie, sweeteners have long been a topic of debate in the diabetes community and have been the subject of many different kinds of scientific studies. These studies have produced an array of mixed results, with some finding that using these sweeteners have no effect on body weight, and others finding that using them is associated with obesity and diabetes.
As their alternate name implies, artificial sweeteners don’t contain any nutrients or energy, so in theory, they can’t directly cause weight gain or affect your metabolism. But it has long been theorized — based on some available evidence — that these sweeteners may actually increase hunger in some people, since their sweet taste could prompt the release of insulin and other hormones that are normally secreted in the body in response to sugar intake. Based on this theory, over time, your body may even learn not to secrete as much insulin or other hormones in response to a sweet taste — with potentially damaging effects when you actually consume sugar.
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But a theory has to be backed up by evidence to be of any practical use — and as a new study shows, the evidence is mixed when it comes to how artificial sweeteners affect metabolism.
No changes in glucose tolerance
The new study, published in the journal Microbiome, involved 46 participants who were randomly assigned to one of four different groups. Each group was assigned to take either the artificial sweetener saccharin, the drug lactisole (which blocks sweet taste receptors in the intestine), saccharin plus lactisole, or a placebo (inactive substance). The dose of saccharin was set at the maximum daily intake recommended by the U.S. Food and Drug Administration.
At the beginning of the study, there were no significant differences between the four study groups in measurements such as blood glucose in response to an oral glucose tolerance test (OGTT), lipids like cholesterol or triglycerides, or body measurements like weight or height. All participants met basic requirements for physical activity and food intake throughout the study period, which lasted two weeks — which included a limit on how much additional artificial sweeteners they could consume. In addition to a having their blood drawn and having basic body measurements taken, participants gave a stool sample to have their gut microbiota (bacteria) analyzed.
At the end of the two weeks, there was no difference between the groups in how participants responded to an OGTT — either in their measured blood glucose levels, or in levels of hormones related to hunger and glucose metabolism. Consuming saccharin, by itself, also had no effect on participants’ gut bacteria — either in terms of balance between different types of bacteria, or in overall numbers.
The researchers concluded that in the time frame of the study, consuming the maximum recommended amount of saccharin had no measurable effects on glucose metabolism or makeup of gut bacteria.
Making sense of the results
There are a few different possibilities that could explain why some studies have found that using artificial sweeteners might change people’s glucose metabolism in harmful ways, yet this study found no such effect.
One possibility is that outside of a controlled study environment, the kinds of people who choose to use artificial sweeteners are somewhat different from people who don’t use them, and may already have a higher risk for conditions like obesity and diabetes. If this is the case, people who use these sweeteners could have higher rate of these conditions without the sweeteners having any role in causing them.
Another possibility, though, is that any harmful metabolic changes in response to these sweeteners take longer than two weeks to develop. If that’s the case, it could explain why many controlled studies — in which participants are randomly assigned to different interventions, and which have mostly been much shorter than observational studies — have found no harmful effects from artificial sweeteners, while longer observational studies have found associations with obesity and diabetes.
And, of course, another possibility is that different artificial sweeteners have different effects — something that would complicate any efforts to make general recommendations about using these sweeteners. In any case, as with so many areas of nutrition, it’s going to take more time and more studies to get a better understanding of the health and safety profile of these products.
Want to learn more about artificial sweeteners? Read “Baking and Cooking With Sugar Substitutes.”