Why haven’t the results of human NMN trials to date been as impressive as the results of animal studies?

NMN has been shown to slow aging-associated decline in rodents, bringing about the following effects:^[1]

• improved insulin sensitivity
• reduced inflammation
• improved mitochondrial function
• improved cognition and brain health

Aside from potential differences between human and rodent physiology that may cause different responses to NMN supplementation, early human clinical trials always err on the side of caution when testing safety. Initial NMN trials in humans tested doses of up to 500 mg NMN daily, with no adverse effects; more recent human trials have tested doses approaching 1000 mg/day. However, in mice NMN is typically administered in doses of up to 500 mg/kg daily, which, taking into account the more rapid turnover of NMN in mice than in humans, may be roughly equivalent to a 75 kg human taking 3,000 mg NMN per day.^[2]