Aspartame's possible effects on the body, topic by topic
What it found
Possible concerns turn up in several areas, from weight and diabetes to pregnancy, the brain and cancer, but little of it has been shown in people.
Most of the mood, brain-ageing and cancer evidence comes from animal and lab studies.
What they found
Studies in people
Weight
It's hard to tell whether sweeteners like aspartame affect weight, because people who choose diet products may eat more calories elsewhere. Some studies found that swapping sugary drinks for diet ones didn't lower the total calories people ate.
Diabetes
The link with type 2 diabetes is unclear. Many studies weren't reliable enough, and reviews haven't reached a firm conclusion.
Autism
One study found that mothers of children with autism had taken in more dietary methanol, much of it from aspartame. Other researchers argue aspartame doesn't cause autism. The authors say the evidence isn't conclusive.
Allergies and skin
Two controlled trials in people found no more reactions to aspartame than to a dummy pill, even in people who believed they were sensitive to it. A few single cases saw skin problems clear up after stopping aspartame.
PKU
People with phenylketonuria must avoid it, because half its weight is released as phenylalanine during digestion.
Animal and lab studies
DNA
Tests for damage to DNA disagree: some found none, some found some. The authors call its effect on DNA unknown.
Brain aging
Animal studies found nerve damage and effects on memory with long-term use.
Studies in people and animals
Pregnancy and children
In rats, aspartame during pregnancy was linked to heavier offspring with poorer blood sugar control. In people, some reports link sweetened drinks in pregnancy to early birth and to allergies in children, but another review found no link with early birth. Studies also linked it to earlier first periods in girls aged 9 to 10.
Cancer
In lab and animal studies, aspartame affected genes involved in cancer, and rats exposed before birth had more lymphomas and leukaemias. In people, results conflict: one study linked it to some blood cancers in men, another found no link, and it does not appear to affect the risk of pancreatic, stomach or womb cancer.
Other findings
Mood
The authors describe how aspartame could lower serotonin and dopamine and raise stress hormones, and conclude that it can cause mood problems and depression. This part rests mostly on how the body processes it and on animal studies.
What the authors conclude
“According to current knowledge benefits of aspartame use outweighs the possible side effects, hence this artificial sweetener remains basic excipient in products.”
Also in their conclusions
- They say it's unclear whether aspartame directly causes disease.
- They advise that research on its safety should continue, and that products should say clearly that they contain aspartame.
How it was done
Aspartame is widely used and its safety is still argued about. The authors set out to gather what's known about its possible effects on the body.
They searched three research databases for studies on aspartame's side effects and picked what they judged to be the most reliable papers and the most common side effects. As a narrative review, it had no fixed rule for which studies to include.
What it can’t tell you
- As a narrative review, the authors chose which studies to discuss.
- Much of what it reports on mood, brain aging and cancer comes from animal and lab studies, not from studies in people.
Who paid
- Funding
- No outside funding. The authors declare no conflicts of interest.
- Authors work at
- Medical University of Lodz; Military Institute of Hygiene and Epidemiology, Warsaw (Poland)
The paper
- Title
- Aspartame—True or False? Narrative Review of Safety Analysis of General Use in Products
- Type
- Narrative reviewThe authors read earlier studies and describe what they found, choosing which studies to include themselves rather than following a fixed method.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Czarnecka, Pilarz, Rogut, Maj, et al. (2021). Aspartame—True or False? Narrative Review of Safety Analysis of General Use in Products. Nutrients. doi:10.3390/nu13061957Free full textPubMed 34200310DOI
Summary written 24 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error