CoQ10 exists in two forms: ubiquinone (oxidized) and ubiquinol (reduced). Understanding the difference helps you evaluate supplement quality.
The oxidized form. This is the form used in most research and most supplements. Your body converts it to ubiquinol after absorption. It is stable, well-studied and cost-effective.
The reduced (active) form. Some evidence suggests better absorption, particularly in older adults and those with reduced conversion capacity. It is more expensive and less stable.
Consistency of daily intake matters more than form for most healthy adults under 50. After 50, ubiquinol may offer absorption advantages. Either form provides CoQ10 for mitochondrial energy and cardiovascular support.