Artificial sweeteners may not help people lose weight, according to a major new Cochrane review of existing studies on the topic.
The review, published Wednesday in the journal BMJ (formerly the British Medical Journal), also found insufficient evidence to attest to the sweeteners’ safety.
With the growing global obesity epidemic and rising concerns about the impact of sugar on weight and other health outcomes, non-sugar sweeteners, such as aspartame and stevia, have become increasingly popular. Evidence regarding the products’ potential benefits and harms has been conflicting, however.
Some studies have reported that the use of artificial sweeteners improves health, primarily by reducing the risk of obesity and type 2 diabetes. Others have found that it increases that risk, as well as the risk of cancer.
To help it develop evidence-based guidelines regarding sweeteners, the World Health Organization (WHO) asked Cochrane, a nonprofit global organization of independent scientific investigators, to look at the best studies conducted to-date on the health effects of artificial sweeteners, particularly in relationship to obesity.
The new review is the result of that examination of the evidence.
Several dozen studies
For the review, Cochrane researchers analyzed 56 studies that compared no or low intake of non-sugar sweeteners with higher intake. The studies involved healthy adults and children, including those who were overweight or obese. Studies that involved people who were specifically trying to lose weight were also included and analyzed separately.
Most of the studies were observational, but 17 of them were randomized clinical trials, considered the gold standard of medical research.
The researchers combed all the studies’ findings for a variety of health-related measures, including weight, blood sugar (glycemic) control, cardiovascular disease, kidney disease, allergies and asthma, mood, eating behavior and dental health. They also assessed the studies for bias and the certainty of the evidence behind their findings.
The analysis revealed that, overall, there appeared to be no statistically significant differences in health outcomes — including weight loss — between people who used artificial sweeteners and those who didn’t. Furthermore, the level of the sweeteners consumed didn’t seem to affect any of the outcomes.
Data from a handful of small studies did suggest small improvements in body mass index (BMI) and fasting blood glucose levels among adults who used artificial sweeteners. But data from other studies suggested that people who consumed lower levels of artificial sweeteners tended to gain less weight than those who consumed higher levels.
In both cases, the certainty of the evidence was low.
The evidence regarding the potential harms of non-sugar sweeteners was also mixed.
For example, one randomized controlled trial reported that children receiving artificial sweeteners performed more poorly on cognitive tests than children receiving sugar, while another study reported the opposite. And a third study found that the type of sweeteners consumed by children made no discernible difference on their cognitive test scores.
The review also found no evidence that artificial sweeteners are linked with an increased risk of cardiovascular disease or cancer.
The certainty of the evidence regarding these and other potential harms was low, however — just as it had been with the potential benefits.
A lack of good research
“For most outcomes, there seemed to be no statistically or clinically relevant difference between NSS [non-sugar sweetener] intake versus no intake, or between different doses of NSS,” the Cochrane reviewers conclude. “No evidence was seen for health benefits from NSSs, and potential harms could not be excluded.”
The reviewers stress that better-quality research is needed before it can be said with any confidence that artificial sweeteners are a safe and effective alternative to sugar.
“The best way to avoid problems associated with sugar is probably to stop drinking sweetened drinks and eating sweet food,” write the experts who assessed the study for “Behind the Headlines,” a consumer-oriented website by Great Britain’s National Health Service.
“The review does not exclude the possibility that non-sugar sweeteners may have a role to play if that seems like too hard a route,” they add. “However, there seems to be no clear evidence that they will improve health directly.”
You can read the study in full on the BMJ website.