Period panty up-cycle project

Hi! My partner and I are currently on a journey of transitioning to natural fibers for fertility & overall health.

He is experienced with making clothing, sewing, etc.

We want to up cycle my current polyester period panties and replace the gusset with natural fibers. Any ideas on skin safe, natural fibers that are moisture wicking/absorbent? Trying to avoid polyester/synthetic at all costs.

EDIT the idea is to create an additional layer or two on top of the current thin layer of polyester.