GLOSSARY

Cholesterol as a Steroid Hormone Precursor
Cholesterol is the precursor used to form classical steroid hormones. Steroidogenic cells convert this C27 molecule to pregnenolone through a mitochondrial reaction that removes part of the side chain.

Availability and access

Cholesterol can come from lipoprotein uptake, cellular synthesis or stored cholesteryl esters. These supplies must be mobilized and delivered to the appropriate mitochondrial compartment before hormone synthesis proceeds.

Regulated conversion

• The initial reaction is catalyzed by CYP11A1.
• In many adrenal and gonadal cells, acute regulation prominently involves StAR-dependent cholesterol delivery.
• Subsequent enzymes determine the final hormone produced.

A nutrition boundary

Cholesterol's precursor role does not mean that eating more cholesterol necessarily raises testosterone or improves performance. Steroid output depends on endocrine drive, cellular regulation, enzyme capacity and feedback rather than substrate intake alone.