Nonnutritive sweeteners confer little to no benefit on weight management
Continuous consumption of nonnutritive sweeteners does not appear to exert weight management benefits, with some studies showing a potential increase in weight over time, according to a systematic review and meta-analysis.
The analysis included seven randomized controlled trials (RCTs; n=1,003, median follow-up 6 months) and 30 prospective cohort studies (n=405,907, median follow-up 10 years) involving adults and adolescents (aged >12 years). Minimum duration of each study was 6 months.
In the RCTs, consumption of nonnutritive sweeteners over 6–24 months did not affect the body mass index (BMI) of hypertensive or overweight participants (n=242; mean difference [MD], -0.37 kg/m2, 95 percent confidence interval [CI], -1.10 to 0.36). [CMAJ 2017;189:E929-E939]
Conversely, in the prospective cohort, nonnutritive sweetener consumption was associated with a moderate increase in BMI over 3–13 years among healthy participants (n=21,256; mean correlation, 0.05, 95 percent CI, 0.03–0.06) and a more substantial BMI increase over 8 years among individuals who consumed nonnutritive sweeteners daily compared with nonusers (n=3,371; MD, 0.77 kg/m2, 95 percent CI, 0.47–1.07).
In the RCTs, nonnutritive sweetener consumption did not affect weight in obese participants (n=791; standardized MD, -0.17). However, weight reduction was more evident in longer-term follow-up (standardized MD, -0.55 over 16–24 months of consumption vs standardized MD, 0.13 over 6 months follow-up). There was evidence of weight gain over 2–4 years with consumption of nonnutritive sweeteners among participants in the prospective cohort (n=32,405; weighted mean correlation, 0.06).
RCTs with short-term follow-up periods (6–12 months, n=683) demonstrated inconsistent effects of nonnutritive sweeteners on waist circumference, while prospective studies with longer follow-up (4–9 years, n=13,312) demonstrated higher incidences of elevated waist circumference, abdominal obesity, and overweight with a higher intake of nonnutritive sweeteners.
Certain outcomes were reported as combinations in individual studies (eg, overweight and obesity), and there was the potential for bias or confounding, both of which were limitations. Thus, the researchers advised caution when interpreting the findings.
“Evidence from RCTs does not clearly support the intended benefits of nonnutritive sweeteners for weight management, and observational data suggest that routine intake of nonnutritive sweeteners may be associated with increased BMI,” said the researchers.
“Although RCTs provide the highest quality of scientific evidence, they often fail to recapitulate chronic dietary exposures that are captured in decades-long cohort studies,” they said, recommending further study assessing the effects of type and dose of nonnutritive sweeteners on weight outcomes, while addressing confounding bias.
“Caution is warranted until the long-term risks and benefits of these products are fully characterized,” they said.