The flush effect opens up restricted vessels all over your body; the FLUSH you see is simply the effect on those closest to your skin.
There seem to be mixed reactions and even those differ from day to day. My suspicion is that it involves bacteria but lets not go there now...
Best is to get a small flush reaction daily, if 100mg does that then great. If you can cut the 100mg in half or quarter to "manage" your flush reaction then fine. If you need more fine tuning then Chlorella allows better dosing at 20mg per tab.
Optimum levels are 1000-1500mg per day, but I see plenty of reasons this may take a long time to achieve...