Does diet affect ms?

Unlikely. I am not aware of a link of diet to causation of ms, but many people with MS tend to be constipated, which can be aggravated by dietary factors.
Somewhat. Prior to 1993, date of initial ms injection, we tried low fat swank diet on many patients, plus employing vitamin therapies such as brewer's yeast. Swank diet is still employed by many, and 2 prior studies suggested relapse rate reduction. Pulse counting to see if food is inflammatory was once also used. Evidence suggests great value, these days for vitamin d supplementation.