What is the worst known side effect from aspartame intake?

There is a multitude of conflicting information concerning aspartame. Some of the worst side effects that are thought to be caused or worsened by long-term aspartame use include: brain tumors; various cancers; mental retardation; diabetes; epilepsy; rapid heart beat; confusion and memory loss, according to the Aspartame Toxicity Information Center.

The National Cancer Institute finds that people who are exposed to aspartame do not have an increased risk of lymphomas or leukemia, according to the American Cancer Society. Despite five studies the FDA quotes to reassure the public that aspartame is safe, research and reports that attempt to link aspartame to cancer continue.