Aspartame
NutraSweet · Equal · E951 · "low-calorie sweetener"
An intensely sweet synthetic compound — about 200 times sweeter than sugar — used in thousands of "diet," "lite," and "sugar-free" products since the early 1980s. In 2023 the World Health Organization formally classified it as possibly carcinogenic to humans.
Why we flag it
In July 2023, the International Agency for Research on Cancer (IARC) classified aspartame as Group 2B — "possibly carcinogenic to humans" — citing limited evidence linking it to liver cancer in observational studies. The companion review by JECFA (the WHO/FAO joint expert committee) maintained that aspartame is safe at the current acceptable daily intake of 40 mg per kg of body weight, but the IARC reclassification was the first formal hazard label from a major global health body.
Beyond cancer, growing observational research has linked daily artificial-sweetener consumption to higher risks of stroke, heart disease, and type 2 diabetes — possibly because they disrupt gut bacteria and the body's natural sweetness-to-calorie signaling. The FDA continues to call aspartame safe, but the regulatory consensus is shifting.
Where you'll find it
Anywhere "diet" or "sugar-free" appears on the label:
- Diet sodas — Diet Coke, Diet Pepsi, Coke Zero (some formulations)
- Sugar-free flavored waters, sports drinks, and powdered drink mixes
- Sugar-free chewing gum, mints, and breath strips
- "Light" yogurts, sugar-free pudding, gelatin cups
- Tabletop sweeteners — blue Equal packets, NutraSweet
- Sugar-free protein bars, "lite" ice creams and frozen desserts
- Many children's chewable vitamins and some medications
What to look for instead
If you want sweetness without sugar, plant-based options have a cleaner track record:
- Stevia — extracted from a South American plant, no calories, well-tolerated
- Monk fruit (luo han guo) — natural zero-calorie sweetener with no aftertaste
- Allulose — a rare sugar that tastes like sugar but isn't metabolized as one
- Erythritol in moderation — naturally occurring sugar alcohol (heart-disease research is still evolving)
- Real sweeteners in small amounts — honey, maple syrup, or coconut sugar are arguably better than chronic artificial sweetener use
The best label signal: "no artificial sweeteners" plus a short ingredient list. USDA Organic certification prohibits aspartame entirely.