Biological age, as measured by clocks, can vary by as much as five years within a single 24-hour period, highlighting the need to test at the same time of day for consistency.

Taking large amounts of NMN or NR supplements can consume your methyl groups, which can be monitored by tracking a rise in homocysteine levels.

Intravenous NAD infusions are biologically nonsensical because NAD is an intracellular molecule that doesn't cross from the blood into cells and is quickly degraded.

NAD levels decrease with age primarily because an enzyme called CD38 becomes more active and chews it up, creating a 'leaky sink' problem.

Urolithin A, sold by the company Timeline, is one of the few supplements with good clinical trial data showing a positive effect on VO2 max and immune function.

Combining multiple longevity supplements, or 'stacking,' is unpredictable and can negate the positive effects of individual compounds, a phenomenon observed in lab experiments.

For at least the next 20 years, we will not have a supplement or medicine that is more powerful for anti-aging than physical activity.

The future of boosting NAD levels may lie in small molecule inhibitors of CD38, which plug the 'leaky sink' rather than just adding more NAD precursors.

A large-scale study found that 93% of our longevity is determined by lifestyle factors, with only 7% being determined by genetics.