What research says about aspartame, the brain and cancer
What it found
Some studies in people link high daily aspartame intake to mood changes and to certain blood cancers, but the cancer link is still disputed.
Much of the brain evidence comes from animals and cells, not people.
What they found
Studies in people
Mood, in people
In an 8-day trial, healthy students given 25 mg of aspartame per kg of body weight a day showed signs of depression and did worse on tests of finding their way, while their short-term memory was unaffected. That dose is below the European acceptable daily intake of 40 mg per kg. People with depression who were given aspartame reported more depression, poor sleep and irritability. Headaches and migraines are commonly reported.
Other trials in people pointed the other way
Trials in adults, children and babies, some at doses above that daily limit, tested its breakdown products and reported no toxic effects. The authors note that one of the trials reporting harm gave aspartame in capsules, which may release it differently from a drink.
Cancer, in people
Some large studies that followed people over time found more non-Hodgkin lymphoma and multiple myeloma among men who consumed more aspartame; the authors say chance could not be ruled out. A study combining trials in people found no link on average. Another found that people with stage 3 colon cancer who drank more artificially sweetened drinks had lower rates of the cancer coming back.
Animal and lab studies
The brain, in animals and cells
Rats and mice given aspartame showed anxiety-like behaviour and did worse in maze tests. In lab tests, aspartame and its breakdown products acted on brain receptors involved in learning and memory.
Cancer, in animals
Rat studies at the Ramazzini Institute in Italy found more malignant tumours, including in rats exposed before birth, at doses close to the European daily limit.
Studies in people and animals
Other links
Studies that followed people over time linked heavy use to heart and blood-vessel disease, and heavy use in pregnancy to asthma and hay fever in children. In animal studies, long-term high doses were linked to kidney damage.
Other findings
How the body handles it
In the gut, aspartame breaks down into two amino acids and a small amount of methanol. The authors note that the methanol from aspartame is several times less than from some everyday foods and drinks, such as fruit juice.
What the authors conclude
“The association between high-dose aspartame usage and increased risk of developing cancers, such as brain tumors or non-Hodgkin lymphomas, is still highly controversial and under investigation and seems to be confirmed by some recent cohort studies.”
Also in their conclusions
- They cite the European Food Safety Authority's conclusion that aspartame raises no concern at current levels of intake, while noting studies that found effects on mood at or below the daily limit.
- Their advice: people with phenylketonuria (PKU) should not have aspartame at all; people with seizures or other nerve conditions may be at risk; and pregnant women should cut down or avoid it. They also want labels to show exactly how much aspartame a product contains.
How it was done
Aspartame is in more than 6,000 foods and drinks and about 600 medicines. The authors set out to gather the research on its possible health risks, focusing on the brain and on cancer.
They read and described earlier studies: trials in people, studies in animals and cells, and large studies that followed groups of people over time. The paper doesn't say how those studies were found or chosen.
What it can’t tell you
- It is a review, not a new study, and it doesn't describe how the studies it discusses were chosen.
- The cancer findings in people come from studies that follow groups over time. Those can show a link but can't show that aspartame causes cancer.
- Much of the brain evidence comes from animals and cells.
Who paid
- Funding
- No outside funding. The authors declare no conflicts of interest.
- Authors work at
- University of Bucharest, Romania; Al-Furat Al-Awsat Technical University, Iraq
The paper
- Title
- Aspartame Safety as a Food Sweetener and Related Health Hazards
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Shaher, Mihailescu, Amuzescu (2023). Aspartame Safety as a Food Sweetener and Related Health Hazards. Nutrients. doi:10.3390/nu15163627Free full textPubMed 37630817DOI
Summary written 24 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error