Any really good antimicrobial fabric that dries fairly fast, will help to cut down on that kind of issue.
I use Linen. Dries faster than wool, and is sturdier/longer lasting in those thin forms.
Polygiene silver treatment and the like might also help for synthetics.
There are different kinds of jock itch too.
There is the Candida yeast type (affects both women AND men) which is more of an internal issue wherein too many carbs and sugars are being eaten and not enough non starchy vegetables and probiotic foods being eaten. While it's a very internal issue, it can show up strongly in the more moist parts of skin that are constantly covered, like ones crotch. Often times this is more an off, on thing which flares up at different times (often due to diet, stress, a lot of sweating, lack of proper hygiene).
Then there is a more true jock itch which is more purely an outer skin infection from a common fungus. If this does not get treated well, the infection can go deeper and become very chronic.
I've had both before, and found they need to be treated very differently in some ways, and yet in other ways similar.
The former needs to be treated primarily via diet, the latter primarily through external applications. Both are helped with very breathable, anti-microbial fabrics, keeping clean and dry, etc.