Many diet soda drinks contain the artificial sweetener aspartame. It is 160 to 220 times sweeter than sucrose, or regular table sugar, and contains almost no calories for a single serving. Despite the FDA granting aspartame a “generally recognized as safe” status, or GRAS, anti-aspartame advocates dispute the safety of the nonnutritive sweetener. Many of the claims about aspartame’s negative effects surround fabrications about its effect on your central nervous system.


Critics of aspartame often claim that it can lead to issues like behavioral change, multiple sclerosis, brain damage and other issues affecting your central nervous system. The University of Hawaii reports that some Internet claims have attempted to link aspartame to health problems soldiers suffered after Operation Desert Storm, which were actually the result of chemical weapons. There is no substantial body of scientific research to back claims that aspartame affects your nervous system.


Before the FDA approved aspartame for human consumption, researchers carried out extensive toxicological studies of aspartame, including a two-year feeding study on rats and dogs and a lifetime feeding study on rats. From these studies, the research teams found that mammals can consume up to 2 g of aspartame per kilogram of bodyweight without any noticeable toxicological effect. The FDA later set the acceptable daily intake at 50 mg per kilogram of bodyweight daily. Though this is only a small percentage of the perceived toxic level for aspartame consumption, it would take a 140-lb man around 17 12-oz diet sodas to reach this amount.


When your body breaks down aspartame, one of the byproducts is the amino acid phenylalanine. Most people can safely process this amino acid, but if you have the genetic disorder phenylketonuria, or PKU, excessive aspartame may put you at risk for irreversible brain damage. In this rare case, aspartame may affect your nervous system. To prevent this potential hazard, the FDA requires that all products containing aspartame carry a warning label informing consumers that the product contains phenylalanine.


Though aspartame received approval by the FDA for human consumption decades ago, researchers continue to investigate any possible neurotoxic effects of the sweetener. In 2002, an extensive review of past and present research at the time found that there is no reason to believe aspartame is a carcinogen or causes neurobehavioral disorders. From this and other reports, the FDA and the Scientific Committee on Food of the European Commission continue to endorse aspartame as a safe sweetener as of 2011.

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