Regul Toxicol Pharmacol. 2002 Apr;35(2 Pt 2):S1-93.
Aspartame: review of safety.
Butchko HH1, 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.
Abstract
Over 20 years have elapsed since aspartame was approved by regulatory agencies as a sweetener and flavor enhancer. The safety of aspartame and its metabolic constituents was established through extensive toxicology studies in laboratory animals, using much greater doses than people could possibly consume. Its safety was further confirmed through studies in several human subpopulations, including healthy infants, children, adolescents, and adults; obese individuals; diabetics; lactating women; and individuals heterozygous (PKUH) for the genetic disease phenylketonuria (PKU) who have a decreased ability to metabolize the essential amino acid, phenylalanine. Several scientific issues continued to be raised after approval, largely as a concern for theoretical toxicity from its metabolic components--the amino acids, aspartate and phenylalanine, and methanol--even though dietary exposure to these components is much greater than from aspartame. Nonetheless, additional research, including evaluations of possible associations between aspartame and headaches, seizures, behavior, cognition, and mood as well as allergic-type reactions and use by potentially sensitive subpopulations, has continued after approval. These findings are reviewed here. The safety testing of aspartame has gone well beyond that required to evaluate the safety of a food additive. When all the research on aspartame, including evaluations in both the premarketing and postmarketing periods, is examined as a whole, it is clear that aspartame is safe, and there are no unresolved questions regarding its safety under conditions of intended use.
There is a great deal of investment in Aspartame, billions. Think just how hard it would be today to admit that it has been harmful all along. They used to have studies that said tobacco was good for you, and in 1950s doctors recommended it in TV ads (and tended to be big smokers).
Besides being the #1 substance generating FDA complaints, if you want a newer study, here is one 2014:
A decade-long study of 60,000 women has confirmed that drinking diet soda sweetened with aspartame is linked with a 30 percent increase in heart attack risk and a 50 percent increase in death risk.The findings, presented at the American College of Cardiology(1), have already been partially swept under the rug with the false explanation that diet drinks don't necessarily cause these risks but are instead merely correlated with them. "Women who toss back too many diet sodas may be trying to make up for unhealthy habits," claims an article on CNBC,(2) while citing no evidence whatsoever to support the claim. Keep in mind that any time a synthetic vitamin is correlated with increased mortality, the entire scientific community immediately describes those synthetic vitamins as "causing" death. Correlation is causation only when industry-funded scientists say it is.
Aspartame is a neurotoxin
What some scientists refuse to explore -- even when the data clearly show a strong death risk association -- is that aspartame is a neurotoxin. The reason why women who drink diet soda have a 50 percent increased death risk is, of course, far more likely to be caused by what's in the diet soda rather than some lifestyle choice.
Aspartame, after all, is made from the feces of genetically engineered bacteria. It is not a natural sugar but rather a chemical compound created in an industrial lab. Used in diet sodas, it breaks down into a number of chemical compounds including formaldehyde and methanol. During digestion, the formaldehyde is oxidized into formic acid, a chemical known to cause toxicity in mammalian biology. Formic acid is also secreted by ants as part of their "chemical weapons" arsenal.
Here is the study: From the American College of Cardiology website:
[A] study led by Ankur Vyas, MD, of the University of Iowa found that postmenopausal women who consumed two or more diet drinks a day were 30 percent more likely to experience a cardiovascular event and 50 percent more likely to die from related cardiovascular disease than women who never, or only rarely, consumed diet drinks. The analysis of 59,614 participants in the Women's Health Initiative Observational Study showed the difference persisted when researchers adjusted for other cardiovascular risk factors and co-morbidities.
http://www.cardiosource.org/en/News-Medi...CV-Disease.aspx 
