Aspartame (brand name Nutrasweet) is a popular artificial sweetener, approximately 200 times sweeter than common table sugar known as sucrose. Aspartame is a dipeptide of the natural amino acids L–aspartic acid and L–phenylalanine–these amino acids or peptides are consumed regular with nearly any animal or plant protein.
When aspartame is ingested, it is hydrolyzed (broken down by water molecules) into its constituent components: aspartate, phenylalanine and methanol, in an approximate 4:5:1 ratio. No aspartame has been found in the bloodstream, since it is so quickly hydrolyzed in the gut, and only the constituent components are absorbed.
To be absolutely clear, there is no difference between aspartic acid and phenylalanine that form aspartame than all “natural forms” of those amino acids that are contained in the proteins of food sources.
Setting aside the absolute safety of the amino acids (the body self-regulates amino acid production and usage), the one concern could be the methanol. Except for the fact that most fruit juices, and the human body itself, produces much more methanol than can be consumed in many cans of diet soda.
A 12 US fluid ounce (355 ml) can of diet soda contains 180 milligrams (0.0063 oz) of aspartame, and for a 75 kg (165 lb) adult, it takes approximately 21 cans of diet soda daily to consume the 3,750 milligrams (0.132 oz) of aspartame that would surpass the FDA’s 50 milligrams per kilogram of body weight acceptable daily intake of aspartame from diet soda alone. Moreover, methanol is not stored in the body, it is metabolized and then excreted. The only way for methanol to have a toxic effect is to ingest an amount so large that it temporarily cannot be cleared from the bloodstream and causes harm.
There just is no plausible pathway that small amounts of simple amino acids, substances that are prevalent throughout all food sources, and a tiny amount of methanol, a substance also found widely in fruits and vegetables, and is manufactured by the body as a byproduct of numerous metabolic processes, could have any effect on anyone. Yes, aspartame must be avoided by people with the genetic condition phenylketonuria, but it is rare, and it has nothing to do with aspartame (other than avoiding it).
Despite this overall lack of plausibility, aspartame has been subject to pseudoscientific attacks almost from the day it launched. Internet hoaxes, government investigations, and unscientific studies have continue to make it appear there might be an issue with aspartame.
That’s why we have real science. The Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive (pdf), published by the European Food Safety Authority (EFSA), came to the following scientific consensus:
- The amount of aspartame that is absorbed into the bloodstream is nonexistent in numerous human and animal studies. This supports the understanding that aspartame is hydrolyzed into its simple, and widely consumed, constituent components in the digestive tract.
- Scientists have found no acute toxic effects of aspartame.
- The available data did not indicate that aspartame had any genotoxic effect.
- There were no aspartame-related increases in neoplasms and tumors in carcinogenecity studies.
- They did recognize some studies indicated that aspartame should not be consumed in large quantities by pregnant women, not necessarily because of the aspartame itself, but possibly because of gastrointestinal disturbances and quality of overall diet. They established that the potentially harmful dose of aspartame is 1000 mg/kg/day, a few hundred cans of diet soda per day.
- They noted that there was no epidemiological evidence for potential associations between consumption of aspartame and cancers.
- A large prospective cohort study in Denmark found no consistent association between the consumption of artificially sweetened beverages (but not with aspartame specifically) during pregnancy and the diagnosis of asthma or allergic rhinitis in children.
- Data did not support genotoxicity of the methanol metabolite of aspartame.
Those are the major points. The panel examined almost every claim about aspartame in detail, and reviewed all the scientific evidence–they found nothing. Aspartame is safe. They did recommend consuming less than 40 mg/kg body weight/day (less than the FDA’s recommended 50 mg/kg/day), that’s still 17 cans of diet soda. There are probably other issues to discuss if you’re at that consumption level of soda.
Once again real science shows real data. The anti-science world pushes scare tactics against aspartame, and fails miserably. This happens a lot.
- Butchko HH, Stargel WW, Comer CP, Mayhew DA, Benninger C, Blackburn GL, de Sonneville LM, Geha RS, Hertelendy Z, Koestner A, Leon AS, Liepa GU, McMartin KE, Mendenhall CL, Munro IC, Novotny EJ, Renwick AG, Schiffman SS, Schomer DL, Shaywitz BA, Spiers PA, Tephly TR, Thomas JA, Trefz FK. Aspartame: review of safety. Regul Toxicol Pharmacol. 2002 Apr;35(2 Pt 2):S1-93. Review. PubMed PMID: 12180494.
- Schernhammer ES, Bertrand KA, Birmann BM, Sampson L, Willett WW, Feskanich D. Consumption of artificial sweetener- and sugar-containing soda and risk of lymphoma and leukemia in men and women. Am J Clin Nutr. 2012 Oct 24. [Epub ahead of print] PubMed PMID: 23097267.
- Stegink LD. The aspartame story: a model for the clinical testing of a food additive. Am J Clin Nutr. 1987 Jul;46(1 Suppl):204-15. Review. PubMed PMID: 3300262.