Absolute objective results. O2 saturation went from 94 to 98% immediately. I’m currently in a Residential Care Facility that is on lockdown because of COVID-19. As a precaution, our temp & pulse Ox is checked daily or twice a day. I’m healthy as are all residents in a large facility other than 2 cases. We’ve been lucky & smart. I’ve been trying to use supplements to keep my immune system strong. I’d taken other arginine citrulline supplements with no noticeable result. My pulse Ox was 94 every day, which is fine, but mine used to be higher ten years ago. The same day I began this supplement, my I2 sats instantly went to 98, and has tested the same everyday since. I find this incredible, and I didn’t expect to have Objective medical proof, but I do because I don’t operate the oximiter, the nurse does. Same device, same nurse, noticeable result. As soon as the lockdown is lifted I’m going to be doing walks, hikes & cardio, & I expect that this supplement will perform the same as it does now. I said I’d tried others but never had a sense that they helped. Anecdotally, I’m sleeping better & longer, feeling generally better & I believe the added oxygen is the reason. I can absolutely recommend this to bodybuilders, sports enthusiasts & anyone, especially at-risk folks with pre-existing conditions because COVID robs the body of oxygen as one if it’s primary disease functions as it messes with pulmonary efficiency. Disclaimer: I’m NOT a medical doctor & this recommendation is a personal one, (ymmv), but I’m probably going to take THIS brand of this supplement as long as I live. For me, I have proof that it works.