Do low‑calorie sweeteners affect blood sugar and health? ^{CEFR B2}

Non-nutritive sweeteners are widespread and many people use them to reduce added sugar intake. A review and meta-analysis by researchers at the Food is Medicine Institute, Fried‑man School of Nutrition Science and Policy at Tufts University, published in Current Atherosclerosis Reports, pooled results from randomized clinical trials and large observational studies to assess how these calorie-free compounds affect cardiometabolic health.

The review analysed randomized trials that used non-caloric comparators such as water or placebo to better isolate direct physiological effects. Across 21 randomized clinical trials in adults, the pooled evidence showed higher fasting insulin and higher HbA1c, a marker of longer-term blood sugar control, and a trend toward worsening insulin sensitivity. The authors write that these signals suggest potential metabolic harms from some sweeteners.

One proposed mechanism is interaction with the gut microbiome. In a trial with detailed microbiome profiling, and in experiments transferring microbes from humans to mice, certain low-calorie sweeteners altered both the composition and the function of gut microbes. Large observational studies also generally linked sweetener consumption to greater cardiometabolic disease risk, although the team noted key limitations: people already at higher risk may select these products, and different sweeteners could have different effects, so grouping them can hide important differences. The authors highlight a policy gap: U.S. labeling requires listing non-nutritive sweeteners but not their amounts, which complicates intake measurement in studies. They call for more carefully designed randomized trials of cardiometabolic risk factors and mechanisms and advise caution in routine use, while noting that replacing very large amounts of added sugar with low-calorie sweeteners may be a preferable alternative.

Source: Tufts University.