The big three to avoid are: aspartame (NutraSweet and Equal), sucralose (Splenda), and saccharin (Sweet ’N Low). These substances are known as excitotoxins, which means that they “overexcite” neurons in the brain, causing degeneration and even death in important nerve cells. When too many nerve cells die, your nervous system begins to malfunction, and it can’t communicate with other parts of your body. This can ultimately lead to nervous-system disorders such as Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease.