144 multiple sclerosis patients took a low-fat diet for 34 years. For each of three categories of neurological disability (minimum, moderate, severe) patients who adhered to the prescribed diet (less than or equal to 20 g fat/day) showed significantly less deterioration and much lower death rates than did those who consumed more fat than prescribed (greater than 20 g fat/day). The greatest benefit was seen in those with minimum disability at the start of the trial; in this group, when those who died from non-MS diseases were excluded from the analysis, 95% survived and remained physically active.