Disclosed are methods and compositions related to methods of treating, ameliorating, mitigating, slowing, arresting, preventing or reversing various diseases and conditions, including age-related obesity, age-related increases in blood lipid levels, age-related decreases in insulin sensitivity, age-related decreases in memory function, and age-related changes in eye function such as macular degeneration. The methods comprise administering nicotinamide mononucleotide (NMN) to a subject. In some embodiments, the administration can be oral administration. Also disclosed are pharmaceutical compositions comprising NMN.
