Bests & Worsts Reviews from Amazon

I am a 65 year old female who has had cancer twice, and have been in remission from stage 4 metastatic cancer for 11 years, due in part I believe to a regimen of supplements including resveratrol, quercetin, Vitamin C, Vitamin D3, and many others. I also walk 3 miles per day, and have tried to avoid sugar and refined carbs for much of that time. Throughout the years I have been following anti-aging and anti-cancer research, as a curious layperson. I have explored writings and videos by David Sinclair of Harvard, Leonard Guarente of MIT, and others, leading me to the recent reports on the postulated benefits to humans of NAD precursor, Nicotinimide Riboside. Leonard Guarente himself takes it, according to his Elyseum website. I started taking the recommended dose in early February, 2015, and can report some positive results, although I believe the dosage level is critical and probably varies widely, depending on one’s age and health status. My experience has been that the prescribed dose of 250 mg. is simply too much. It revved me up, but the rebound effect was very noticeable--exhaustion. A suitable analogy might be constantly gunning and red-lining one’s old, inefficient engine. So I cut back to a half dose every other day. Much better. I still feel energetic--and optimistic--but am not completely exhausted hours later after the initial burst of energy has waned. It would certainly seem logical that younger, healthy, and/or athletic folks already have sufficient amounts of NAD, so they probably wouldn't notice much if any improvement from supplementation with NR. However, old folks have NAD deficiency as a result of aging, and probably see a much greater benefit from supplementation with NR. which increases NAD. I am guessing that most of the folks reporting little or no benefit from NR are either younger & healthy and have plenty of NAD; or, perhaps are taking far more than they need, producing some sort of negative hormesis-like response; or are not taking complementary doses of resveratrol, or other pterostilbenes, which operate in tandem with NAD as a substrate to influence anti-aging sirtuins. An update: I am now 68 and still taking NR from various makers, who add various components along with NR (all Niagen based) and at various dosages.. The 250 mg. dose is now my standard, however, and I no longer have the exhaustion effect. I don't know why, but it is gone and I am feeling great. I always take resveratrol daily, and many other supplements as noted above. I am also considering the other NAD precursor which is starting to become available, nicotinamide mononucleotide, but the price has got to come down significantly and some major advantage over NR demonstrated. Another possible effect from taking the 250 mg. NR dose is noteworthy: my fasting blood sugar is now running in the 60's and 70's regularly, but I do not feel bad. I have been doing a form of intermittent fasting for some time, but even when I have a regular meal, a few hours later my fasting glucose is back in the 60's & 70's. I test it daily. This may in fact serve as a long-term indicator of the continued efficacy of NR. I have never had fasting glucose levels this low, before taking 250 mg. of NR daily.