While I do not have the background to comment on the whole glutathione thing, I feel the need to comment on the anerobic training recommendations from Nathan.
My basic guidance for those I coach is that unless the runner is knocking on the back door to the elite runners in his or her age group, speed drills for racing 5K and longer races are pretty much worthless compared to building a large and primarily slow base of mileage. For somone as fast Nathan, speed work may well pay dividends, however, for us mere humans, I've yet to see any evidence speed work will yield any benefits in overall race performance; granted the final 100 meters may be faster, however, the first 4,900 meters will most likely be quite a bit slower.
The other caution I give those I coach is that the faster the workouts, the higher the likelihood of injury. Long story short, build a large base of mileage and save the fast stuff for racing.