Q: Can aspartame cause depression?
A: No well-designed human studies have ever found that aspartame causes neurological or psychiatric problems, including migraines, depression, insomnia or memory loss. In fact, hundreds of studies have exonerated aspartame.
In 2007, for example, a massive review (500 studies) by a panel of experts from medical schools and research institutions in the U.S., Britain,] and the Netherlands found no evidence that aspartame has negative effects in the body or mind, even when consumed at high levels.
It’s true that this review was funded by a Japanese company that makes aspartame, but the company did not have any influence on the published results, which appeared in Critical Reviews in Toxicology, a respected journal.
One small and poorly controlled study in 1993 did conclude that people with mood disorders should avoid aspartame, but this was the sole study with such findings. There were only eight people in the treatment group, and five in the control group—not enough to provide statistically valid conclusions. Some went into the study believing they were prone to adverse reactions to aspartame. The trial lasted only 20 days. Despite its dubious quality, the psychiatrist who conducted it wanted the Senate to pass legislation rescinding the approval of aspartame. Of course, this generated a lot of publicity.
Aspartame remains controversial, in spite of clear evidence that it is safe. Its chief ingredients, phenylalanine and aspartic acid, are amino acids that occur naturally in foods and in the body. As the warning label states, people with the rare genetic disorder phenylketonuria, which keeps them from properly processing phenylalanine, should avoid aspartame as well as foods rich in this amino acid.