β-Nicotinamide Mononucleotide (NMN) is safe and well tolerated in healthy adult males and females at an oral dose of 900 milligrams once daily for up to 8 weeks. A clinical study in middle-aged healthy adults demonstrated that NMN supplementation increases blood NAD concentrations, with daily oral doses up to 900 milligrams remaining well tolerated and safe. Clinical efficacy, measured by plasma NAD concentrations and physical performance, peaked at a daily oral dose of 600 milligrams. Other studies indicate NMN may cause side effects including abdominal pain, diarrhoea, flatulence, and upper respiratory tract issues. Whilst limited data suggest NMN is relatively safe for short-term use, evidence supporting its long-term administration is lacking.