Aspartame
Aspartame is an artificial, non-saccharide sweetener commonly used as a sugar substitute in foods and beverages. It is 200 times sweeter than sucrose, and is a methyl ester of the aspartic acid/phenylalanine dipeptide with brand names NutraSweet, Equal, and Canderel. Discovered in 1965, aspartame was approved by the US Food and Drug Administration in 1974 and re-approved in 1981 after its initial approval was briefly revoked.
Aspartame is one of the most studied food additives in the human food supply. Reviews by over 100 governmental regulatory bodies found the ingredient safe for consumption at the normal acceptable daily intake limit.
Uses
Aspartame is about 180 to 200 times sweeter than sucrose. Due to this property, even though aspartame produces roughly the same energy per gram when metabolized as sucrose does,, the quantity of aspartame needed to produce the same sweetness is so small that its caloric contribution is negligible. The sweetness of aspartame lasts longer than that of sucrose, so it is often blended with other artificial sweeteners such as acesulfame potassium to produce an overall taste more like that of sugar.Like many other peptides, aspartame may hydrolyze into its constituent amino acids under conditions of elevated temperature or high pH. This makes aspartame undesirable as a baking sweetener and prone to degradation in products hosting a high pH, as required for a long shelf life. The stability of aspartame under heating can be improved to some extent by encasing it in fats or in maltodextrin. The stability when dissolved in water depends markedly on pH. At room temperature, it is most stable at pH 4.3, where its half-life is nearly 300 days. At pH 7, however, its half-life is only a few days. Most soft-drinks have a pH between 3 and 5, where aspartame is reasonably stable. In products that may require a longer shelf life, such as syrups for fountain beverages, aspartame is sometimes blended with a more stable sweetener, such as saccharin.
Descriptive analyses of solutions containing aspartame report a sweet aftertaste as well as bitter and off-flavor aftertastes.
Acceptable levels of consumption
The acceptable daily intake value for food additives, including aspartame, is defined as the "amount of a food additive, expressed on a body weight basis, that can be ingested daily over a lifetime without appreciable health risk". The Joint FAO/WHO Expert Committee on Food Additives and the European Commission's Scientific Committee on Food have determined this value is 40 mg/kg of body weight per day for aspartame, while the FDA has set its ADI for aspartame at 50 mg/kg per day an amount equated to consuming 75 packets of commercial aspartame sweetener per day to be within a safe upper limit.The primary source for exposure to aspartame in the US is diet soft drinks, though it can be consumed in other products, such as pharmaceutical preparations, fruit drinks, and chewing gum among others in smaller quantities. A can of diet soda contains of aspartame, and, for a adult, it takes approximately 21 cans of diet soda daily to consume the of aspartame that would surpass the FDA's 50 mg/kg of body weight ADI of aspartame from diet soda alone.
Reviews have analyzed studies which have looked at the consumption of aspartame in countries worldwide, including the US, countries in Europe, and Australia, among others. These reviews have found that even the high levels of intake of aspartame, studied across multiple countries and different methods of measuring aspartame consumption, are well below the ADI for safe consumption of aspartame. Reviews have also found that populations that are believed to be especially high consumers of aspartame, such as children and diabetics, are below the ADI for safe consumption, even considering extreme worst-case scenario calculations of consumption.
In a report released on 10 December 2013, the EFSA said that, after an extensive examination of evidence, it ruled out the "potential risk of aspartame causing damage to genes and inducing cancer" and deemed the amount found in diet sodas safe to consume.
Safety and health effects
The safety of aspartame has been studied since its discovery, and it is a rigorously tested food ingredient. Aspartame has been deemed safe for human consumption by over 100 regulatory agencies in their respective countries, including the US Food and Drug Administration, UK Food Standards Agency, the European Food Safety Authority, Health Canada, and Food Standards Australia New Zealand.Metabolism and body weight
reviews of clinical trials showed that using aspartame in place of sugar reduces calorie intake and body weight in adults and children. A 2017 review of metabolic effects by consuming aspartame found that it did not affect blood glucose, insulin, total cholesterol, triglycerides, calorie intake, or body weight. While high-density lipoprotein levels were higher compared to control, they were lower compared to sucrose.In 2023, the World Health Organization recommended against the use of common non-sugar sweeteners, including aspartame, to control body weight or lower the risk of non-communicable diseases, stating: "The recommendation is based on the findings of a systematic review of the available evidence which suggests that use of NSS does not confer any long-term benefit in reducing body fat in adults or children. Results of the review also suggest that there may be potential undesirable effects from long-term use of NSS, such as an increased risk of type 2 diabetes, cardiovascular diseases, and mortality in adults."
Phenylalanine
High levels of the naturally occurring essential amino acid phenylalanine are a health hazard to those born with phenylketonuria, a rare inherited disease that prevents phenylalanine from being properly metabolized. Because aspartame contains phenylalanine, foods containing aspartame sold in the US must state: "Phenylketonurics: Contains Phenylalanine" on product labels.In the UK, foods that contain aspartame are required by the Food Standards Agency to list the substance as an ingredient, with the warning "Contains a source of phenylalanine". Manufacturers are also required to print "with sweetener" on the label close to the main product name on foods that contain "sweeteners such as aspartame" or "with sugar and sweetener" on "foods that contain both sugar and sweetener".
In Canada, foods that contain aspartame are required to list aspartame among the ingredients, include the amount of aspartame per serving, and state that the product contains phenylalanine.
Phenylalanine is one of the essential amino acids and is required for normal growth and maintenance of life. Concerns about the safety of phenylalanine from aspartame for those without phenylketonuria center largely on hypothetical changes in neurotransmitter levels as well as ratios of neurotransmitters to each other in the blood and brain that could lead to neurological symptoms. Reviews of the literature have found no consistent findings to support such concerns, and, while high doses of aspartame consumption may have some biochemical effects, these effects are not seen in toxicity studies to suggest aspartame can adversely affect neuronal function. As with methanol and aspartic acid, common foods in the typical diet, such as milk, meat, and fruits, will lead to ingestion of significantly higher amounts of phenylalanine than would be expected from aspartame consumption.
Cancer
regulatory agencies, including the FDA and EFSA, and the US National Cancer Institute, have concluded that consuming aspartame is safe in amounts within acceptable daily intake levels and does not cause cancer. These conclusions are based on various sources of evidence, such as reviews and epidemiological studies finding no association between aspartame and cancer.In July 2023, scientists for the International Agency for Research on Cancer concluded that there was "limited evidence" for aspartame causing cancer in humans, classifying the sweetener as Group 2B. The lead investigator of the IARC report stated that the classification "shouldn't really be taken as a direct statement that indicates that there is a known cancer hazard from consuming aspartame. This is really more of a call to the research community to try to better clarify and understand the carcinogenic hazard that may or may not be posed by aspartame consumption."
The Joint FAO/WHO Expert Committee on Food Additives added that the limited cancer assessment indicated no reason to change the recommended acceptable daily intake level of 40 mg per kg of body weight per day, reaffirming the safety of consuming aspartame within this limit.
The FDA responded to the report by stating: