Have any of these studies been done in labs by real scientists/doctors? I didn't see any PHDs next to any of those names. I know alot of the supplements we take have never really had many if any actual professional scientific documentation/studies/etc. done. Alot of dosage amounts on many supps seem merely speculation as the dosages are " recommended" amounts not prescribed amounts for results. Kinda seems like recommendation alot of the time is a base or safe( from a liability standpoint) amount the user has to work from to test what's effective on themselves.
Another thought is with supplements such as creatine doesn't weight and muscle size half a factor in determining dosage amount? I would think a 220lb guy vs. a guy that weighs 150 with roughly same height and bf% would have different absorption rates and tolerances considering the size difference.
The studies cited show that muscle creatine saturation can be maintained with as little as two to four grams a day; that is the amount needed to maintain maximal muscle saturation, NOT the maximum amount that can be absorbed. Moreover, studies exist showing that muscle creatine saturation can be achieved in 28 days with as little as three grams a day. All that said, there is little reason to halve your five-gram scoop given the low cost of creatine, and even if perceived benefit from dosing five grams twice a day is placebo, it is nonetheless a benefit. Again, given the low cost, there is no reason not to do it if you feel it improves your results. Also, ten grams a day of creatine will not bloat you more than five grams, assuming creatine does indeed bloat you at all, since the idea that creatine causes bloat is largely horse****. As far as supplements being researched or not, creatine has been researched to death. If someone cites a study done on creatine, it's probably legit because there are thousands of them out there. Lastly, if I recall correctly (and I think I do), the study showing down-regulation of creatine transporters with long-term use also showed that the down-regulation did not negatively effect muscle creatine stores with continued supplementation.