Is aspartame (E951) bad for you? What the safety data actually says
Aspartame is one of the most-studied ingredients on the planet — and one of the most argued-about. Here's what EFSA, JECFA and the IARC actually concluded, what the numbers mean, and how to see it on your own labels.
Aspartame — additive number E951 — is a low-calorie sweetener found in thousands of "diet", "zero" and "no added sugar" products. It's also one of the most searched-for ingredients on any food label, usually alongside the question: is it actually bad for me? The honest answer is that this is a question for regulators and toxicologists, not for a marketing page — so this article sticks to what the official bodies have concluded, and points you to the primary sources.
What aspartame is and where it turns up
Aspartame is roughly 200 times sweeter than sugar, so tiny amounts replace a lot of it. That's why it appears in diet soft drinks, sugar-free chewing gum, tabletop sweeteners, some yoghurts, and many "no added sugar" products. On an EU label it shows up as "aspartame", "E951", or under the phrase "contains a source of phenylalanine" — the latter matters for people with phenylketonuria (PKU), a genetic condition for whom it must be avoided.
What the regulators concluded
Two things are worth separating: hazard (could something cause harm in principle) and risk (does it cause harm at the amounts people actually consume).
- EFSA (the European Food Safety Authority) set an Acceptable Daily Intake (ADI) of 40 mg per kg of body weight per day after a full re-evaluation, and concluded aspartame is safe at that level for the general population. For an average adult, reaching that limit means drinking a large number of diet soft drinks every day.
- JECFA (the WHO/FAO joint expert committee) reviewed the evidence in 2023 and kept the same ADI.
- IARC (the WHO cancer-research agency) in 2023 classified aspartame as "possibly carcinogenic to humans" (Group 2B). This is a hazard classification about strength of evidence — the same category as aloe vera extract and pickled vegetables — not a statement about how risky it is at normal intake. JECFA, which assesses risk, did not change the intake limit in response.
The short version regulators are telling you: at the amounts a typical person consumes, aspartame is considered safe — but if you'd simply rather avoid it, that's a legitimate personal choice, and the label is where you check.
How to actually spot it
Reading "E951" on an ingredient list tells you the additive is present; it doesn't tell you the amount, and it doesn't tell you whether that product fits your goals overall. That's the gap Forkin closes: scan the barcode and you see the additive, its regulatory context, the processing level, and the product's nutrition and environmental score in one place — instead of googling every E-number one at a time. It's the same reference layer behind our public additive index, wired to real products.
Want the bigger picture on the numbering system? Our guide to E-numbers explains how additives get approved and what the codes mean. And the scores that sit next to them are documented, not proprietary hand-waving — see the methodology.