PROTIP: Press 'i' to view the image gallery, 'v' to view the video gallery, or 'r' to view a random entry. Mountain Dew is a citrus-flavored soft drink distributed by PepsiCo Inc. and Doritos is a brand of chip distributed by Frito-Lay, which is owned by PepsiCo as well.
Other common things that can cause toenail fungus include: 1  Improper footwear, especially tight-fitting shoes. 2  Medical conditions such as diabetes and other circulatory conditions. 3  Toenail polish that is applied in layers.  Hosiery, socks, and shoes that do not allow the feet to breathe.
A bacterial infection can cause thickening, and this can arise due to some trauma to the nail. Possible Causes of Crumbling & Dry Toenails. Our toenails contain something called keratin. A toenail fungus will feed on keratin, which is what makes our nails dry and crumbling when we have an untreated fungus.