Aspartame is an artificial sweetener and a popular sugar substitute sold under the brand names Nutrasweet and Equal. It is present in low-calorie food and drinks and some medications.

Despite its extensive use and popularity, aspartame has become a source of controversy in recent years, with some research suggesting the sweetener has adverse health effects.

It is not clear if aspartame helps people lose weight, as it may also increase appetite and affect a person’s metabolism. Aspartame may also be unsafe for certain people.

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The Food and Drug Administration (FDA) first approved aspartame for use as a sweetener in 1974. The FDA has reviewed over 100 studies about the safety of aspartame.

Agencies in Europe, Canada, and many other countries also approve its use, including:

Although there have been some concerns that aspartame may have the potential to cause cancer, risk assessments have found limited evidence for this in humans.

Following these assessments, the Joint Expert Committee on Food Additives (JECFA) reaffirmed an acceptable daily intake (ADI) of 40 milligrams (mg) of aspartame per kilogram (kg) of body weight.

Most people will not exceed this amount. If a person weighs 68 kg, they would need to drink around 19 cans of soda or consume over 85 packs of aspartame every day to exceed the ADI.

People who eat and drink products containing aspartame consume around 4.9 mg/kg daily on average, which is around 10% of JECFA’s recommended ADI.

Aspartame may have the following side effects:

Effects on body weight

Aspartame contains 4 calories per gram (g), which is a similar amount to sugar. However, it is around 200 times sweeter than sugar, so only a tiny amount of aspartame is necessary to sweeten foods and drinks. This is why people often use it in weight loss diets.

However, a 2021 animal study found that aspartame ingestion in rats led to increases in body weight and fat mass due to increases in energy efficiency. Researchers associated this effect with the amount of aspartame rather than the form of ingestion.

Similarly, a 2023 questionnaire study found an association between aspartame intake and greater body weight, waist circumference, body mass index (BMI), and increases in all three over 25 years.

However, a 2018 trial found that aspartame did not affect body weight in lean adults over 12 weeks.

Effects on appetite

Some research suggests that aspartame may increase appetite.

However, other research does not support these findings. For example, a 2018 study looked at aspartame intake in 100 lean adults with a BMI of between 18 and 25 who were between the ages of 18 and 60 years.

Researchers found that aspartame intake over 12 weeks had no effects on appetite, body weight, or blood sugar management.

Further research is necessary for a better understanding of the link between aspartame and appetite.

Effects on metabolism

A 2024 animal study suggests that long-term consumption non-nutritious sweeteners, including aspartame, does not cause adverse metabolic effects.

In contrast, a 2021 review suggests there may be a link between aspartame and metabolic conditions such as type 2 diabetes. However, more research is necessary to understand this potential connection.

The authors also suggest that the metabolic products of aspartame may be more harmful than aspartame itself.

A 2021 animal study associated aspartame with glucose intolerance, concluding that aspartame may have adverse effects on metabolism.

Ultimately, more research in humans is necessary for experts to understand aspartame’s potential long-term metabolic effects.

The FDA states that aspartame is safe for the general population when manufacturers follow good practices and approved conditions of use.

However, some research suggests potential health risks.

Short-term effects

A 2019 study looked at the short-term effects of aspartame on the blood and biochemical measurements in female Swiss albino mice over 30 days.

The study found that consuming aspartame was harmful to the mice and produced adverse effects relating to the blood and biochemical measurements. However, researchers need further evidence and human studies to support these findings.

Long-term effects

There have been some concerns about the effects of aspartame on the central and peripheral nervous systems.

A 2021 review highlights research that suggests long-term use of aspartame may increase the risk of neurodegenerative disorders, including:

Long-term aspartame use may adversely affect the sciatic nerve in the lower back.

Future human studies may help scientists find out more about the effects of aspartame on nerve structure and function.

Research in the 2021 review suggests that aspartame may also affect or cause:

  • long-term changes in behavior
  • mental stress
  • memory and learning difficulties
  • changes in blood corticosterone levels
  • contact dermatitis

Cardiovascular health

Recent research also highlights a potential link between aspartame and an increased risk of heart disease and stroke. For example, a 2023 review suggests that research links long-term use of artificial sweeteners with a higher risk of the following:

The researchers state that further research is necessary for experts to understand the potential link between artificial sweeteners and cardiovascular health.

A 2022 study evaluated the artificial sugar intake of an online cohort of 103,388 people. They found an association between artificial sugar intake and a higher risk of cardiovascular diseases.

Specifically, they associated aspartame intake with a higher risk of strokes.

A report from the U.S. Department of Health and Human Services assessed a number of studies looking at the potential risks of aspartame.

The report highlights inconsistent, limited evidence that suggests a possible link between aspartame and some hematopoietic cancers in males, although researchers require further evidence from human studies.

The International Agency for Research on Cancer classifies aspartame as “possibly carcinogenic to humans.” Other substances in this category include lead and gasoline engine exhaust fumes.

Experts suggest there are no significant safety concerns for aspartame consumption at the ADI of 40 mg/kg.

Phenylketonuria (PKU) is a genetic metabolic disorder that increases levels of the essential amino acid known as phenylalanine in the blood. People with PKU are unable to metabolize phenylalanine properly, so they will need to avoid or limit their intake of it.

Phenylalanine is one of two amino acids that make up aspartame. Aspartame provides significantly lower amounts of phenylalanine than everyday food sources, such as meat, fish, eggs, and dairy products.

People with PKU need to monitor all dietary sources of phenylalanine to avoid toxic levels. As a result, all products containing phenylalanine in the United States carry a label.

Many foods and drinks that carry the label “sugar-free” may contain some form of artificial sweetener.

The following could contain aspartame:

  • diet soda
  • low-sugar juices
  • flavored water
  • low-fat yogurt
  • low-fat flavored milk
  • nutrition bars
  • sugar-free puddings
  • gelatins
  • low-fat or light ice cream and popsicles
  • low-calorie tabletop sweeteners, such as Equal
  • some prescription and over-the-counter medicines, including chewable vitamins

Those wishing to limit their intake of aspartame may want to try an alternative natural sweetener, such as:

There is still much controversy surrounding the safety of aspartame, despite approval from authorities around the world.

Some evidence suggests aspartame may have adverse effects on health. However, further studies in humans is necessary to support many of these findings.

Organizations such as the FDA have approved aspartame as safe for human consumption within a certain daily limit.