L-citrulline
Supplement
A nitric oxide precursor, 2 grams of which was combined with glutathione in a study, though the dose was lower than typical.
Mentioned in 3 videos
Videos Mentioning L-citrulline

Improving Sexual & Urological Health in Males and Females | Dr. Rena Malik
Andrew Huberman
An over-the-counter supplement that increases nitric oxide availability, thought to improve blood flow to genitals. Cautioned due to potential side effects like cold sores.

How to Control Your Metabolism by Thyroid & Growth Hormone
Andrew Huberman
A supplement that acts as a biological prerequisite for arginine and can lead to greater arginine increases than arginine itself, with powerful effects on vasodilation and potential increases in growth hormone. It also lowers blood pressure and reduces fatigue.

Effective Reps, Antioxidants, Optimal Training Volume, and Lauren Colenso-Semple (Episode 18)
Stronger By Science
A nitric oxide precursor, 2 grams of which was combined with glutathione in a study, though the dose was lower than typical.