Ringworm is a topical fungal infection and there is no special diet to my knowledge to follow.
Ringworm is a skin and scalp disease caused by several different kinds of fungi. Ringworm on the scalp usually makes a bald patch of scaly skin. People with ringworm on other parts of their skin can have a ring-shaped rash that is reddish and may be itchy. The rash can be dry and scaly or wet and crusty.
Ringworm commonly grows in wet warm areas such as swimming pool areas, gyms, showers, wet soil or dirt, etc. You can also commonly get ringworm from cats or animals. Keeping your home clean from fungi by using bleach and water (dilution 10:1) will help ringworm from spreading. Most disinfectants that are made of benzalkonium chloride will also keep fungi out of your home and control spreading.
I used the All Stop ringworm products (Sulfinex Cream and the Gel) recently for myself and my children successfully. I would use them again if ended up with ringworm. allstop.com. hope this helps