Aspartame is ubiquitous—and potentially risky, according to studies

By Carol Nathan | Fact-checked by Anastasia Climan, RDN, CD-N
Published March 17, 2023

Key Takeaways

  • Reducing sugar intake in the diet by substituting artificial sweeteners such as aspartame is a common health recommendation.

  • Studies, however, are pointing to risks and disadvantages of consuming artificial sweeteners.

  • In particular, adverse health effects of aspartame are being reported in the areas of diabetes, fertility, anxiety, and cancer risk, according to research.

The use of non-nutritive sweeteners such as aspartame as food additives has increased over the past three decades as a result of dietary recommendations to reduce sugar intake—with the blessing of the FDA. But that may be changing.  

Aspartame is used in the manufacture of thousands of foods, medicines, and beverages, and is also added by consumers to their diets as a sweetener. Despite this high usage, the safety of aspartame has now become controversial, and adverse effects are being reported, including effects on diabetes, fertility, anxiety, and cancer risk. 

Previously deemed safe

Aspartame was approved by the FDA in 1981, 1983, and 1996 for various consumer sweetener uses and foods.[] In 1983, the FDA approved the use of aspartame in carbonated beverages, and in 1996, it was approved for use as a general purpose sweetener.

When issuing these approvals, the FDA concluded that aspartame was safe for the general population under certain conditions, with the only exception being people with phenylketonuria (PKU).

Diabetes effects

A Japanese research team reviewed the literature to determine if certain artificial sweeteners are beneficial for patients with diabetes. They looked at studies of sucralose, acesulfame potassium (ACE K), aspartame, and saccharin.[]

Overall, they found that there were a few advantages, such as being noncaloric, flavor enhancing, and promoting of GLP2. However, the disadvantages were much more significant, and include increased rates of:

  • Mortality

  • Cerebrovascular risk

  • Cardiovascular risk

  • Cancer risk 

  • Hyperglycemia 

  • Disordered HDL

  • Impaired FGF21 secretion (hormone involved in diabetes)

Fertility effects

A study by researchers in Taiwan looked at aspartame in women to see if it affected fertility.[] The study included 840 pregnant women and also included animal and cell experiments. The results showed that aspartame consumption was associated with an increased risk of infertility, with an odds ratio of 1.30 (95% confidence interval: 0.87, 1.93). 

In explaining the mechanism for the infertility effect, the investigators noted that aspartame increased oxidative stress in the reproductive system, including the granulosa cells and ovaries. It also reduced mitochondrial function, and boosted the compensatory mechanism to increase mitochondrial biogenesis. However, that compensatory process does not recover from the mitochondrial dysfunction caused by aspartame, and the result is an increased risk of infertility.

On the basis of these findings, the authors suggest that HCPs should advise patients who are trying to get pregnant to reduce their aspartame consumption. In addition, dietary guidelines for aspartame should be reevaluated. 

Anxiety risk 

While preclinical research in animals does not necessarily apply to humans, a study of aspartame ingestion done in mice showed that it produced pronounced anxiety behavior as measured by various maze tests.[] The anxiety behavior was alleviated by diazepam, which the authors state confirmed the findings. In addition, the researchers found that the anxiety effects lasted for 2 generations in the males exposed to the sweetener, showing intergenerational consequences. 

For the study, the mice were provided with drinking water containing aspartame at 8% to 15% of the FDA-approved maximum daily human intake for 12 weeks. The dosage was equivalent to two to four small (8-ounce) cans of diet soda a day for humans. The control group of mice was provided with plain drinking water.  

Cancer risk

Some good news comes from another review of low-calorie sweeteners (in particular, aspartame), which found no association with an increased risk of cancer.[] The study used NHANES data for the US for the years 1988 to 2018. This finding clearly contradicts the cancer risk findings discussed in the diabetes section above, but that is the nature of clinical research. 

This was a systematic review conducted to assess the potential carcinogenicity risk associated with consumption of aspartame. More than 1,300 studies with animal and epidemiological datasets showed lack of genotoxicity or other plausible cancer pathways. 

What this means for you 

If you make nutritional recommendations to your patients, it makes sense to caution them about aspartame, especially if they are trying to get pregnant, have diabetes, or have anxiety. In patients with diabetes who are continuing to use aspartame, it would be useful to monitor them over time for changes in blood glucose. Also note that other artificial sweeteners, such as erythritol, have been shown to also be potentially associated with a risk of heart attack, stroke, and even death, according to a recent Cleveland Clinic-led study published in Nature Medicine.[]

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