NAD+ levels naturally decline significantly with age. This decrease is believed to be a contributing factor to the aging process and age-related health issues, as it impairs the cell's ability to maintain healthy energy and repair mechanisms.
The difference lies in the method of administration:
IM (Intramuscular): The vitamin is injected directly into a large muscle (like the arm or hip). This provides a steady, relatively fast absorption into the bloodstream.
IV (Intravenous): The vitamin is delivered directly into a vein. This provides 100% immediate bioavailability and is the fastest way to achieve high concentrations in the body.