The people with the world’s highest risk of Lou Gehrig’s disease were the Chamorro people, who were the native people of Guam. These people also had a high risk of Alzheimer-like dementia and disorders like parkinsonism. The problem didn’t seem to be genetic or contagious, and the diseases became less common when the population became more Americanized after World War II. These facts suggested that the problem resulted from something that the people had been eating.
Even Late in Life, a Low-Fat Diet Helps
The more fat you eat, the more likely you are to lose your marbles in your old age. This graph came from an article that explains why it’s reasonable to conclude that the fat in the diet is the culprit. It also explains that even late in life, a change to a better diet is beneficial.
The article mentions that in Europe and North America, higher fish consumption seemed to provide some reduction in risk. That may be because the fish were simply replacing foods that were even more dangerous. It doesn’t mean that a health-optimizing diet for a human being would include fish.