Can you prevent lou gehrig's disease?

No. Als is relatively rare, with 90% sporadic and 10% genetic (25% of which have mutations involving copper/zinc superoxide dismutase). There is no specific or successful treatment to date, and no known approach to prevent the disease even if one is a member of a family at risk.
No. Lou gerhig's disease has no known cause and there is no treatment. It is a progressive muscle weakness and muscle loss as a result of dying neurons (nerve cells) in the brain stem and spinal cord.
No. As far as we know this illness is not preventable at the current time. Research is ongoing.