According to Examine.com
"The recommended oral dose of muira puama appears to be 1000-1500mg of a 4:1 concentrated extract (equivalent to 4,000-6,000mg of the basic extract). It is unsure if this is the optimal dose or whether it needs to be taken with a meal.
3.1. Erectile Properties
https://examine.com/supplements/muira-puama/Muira puama (Marapuama, Potency Wood) is a traditionally used aphrodisiac and nerve tonic in the Brazil region.