I won the Dartmoor vale marathon a couple of years ago (v small race with about 150 runners)
What was very surreal was being led by the guide vehicle, a large 4x4 driving 20m ahead of me at all times. I was completely alone for most of the race (won by 20 minutes in the end) apart from this truck.
Agree condition differences between the two make comparisons difficult but my takeaway was that beetroot could have added at most a few seconds and most probably nothing at all.
Beetroot seems to have the attention of sports scientists and a few pro athletes. i wasn't convinced and wanted my own data. If you don't think this provides any relevant evidence then fine. Not sure it warrants the abuse above though tbh.
Pint of beetroot juice daily pre-race. Decent training (90-105km pw). Flat course, laser focus, all-out effort, even pacing. Result: 2.43 pb
London marathon apr 2014:
no beetroot juice. No training at all for previous 6 months beyond a couple of 20k and some erging. Hot day, no attempt on pb, bad pacing (4min pos split). 30sec pee break at 20 miles. Result: 2.47.
now you can argue how much of that 4 mins the lack of training and focus contributed to, but my feeling is that with better prep I could have replicated the 2.43 pb and that beet root juice has no effect at all.