Are there vitamins to help with toenail fungus? The answer is probably, but their impact would be minor. Toenail fungus is an infection of the toenail. For a vitamin to help with a toenail infection it would have to be resorbed by the stomach and transmitted down in such a concentration to the toe to be effective. The only known and proven cure for toenail fungus is oral Lamisil. There are topicals that can be effective. But if you want a cure see a Podiatrist and get a prescription for Lamisil.
That does not mean vitamins cannot help. They can aid in the fight against toenail fungus. What vitamins might be of assistance? Consider a Vitamin such as Vitamin C. Why vitamin C? The same reason you drink orange juice to prevent colds. Vitamin C can help boost the immune system and since toenail fungus is an infection fought by the immune system any help you can give the immune system can be effective.
The other vitamin to consider is hair, skin and nail vitamins. They tend to include Biotin, which is what a large percentage of the toenail is made from. Toenail fungus is a disease of the toenail, it makes the toenail unhealthy. Anything you can do to help strengthen the toenail can help with the treatment of toenail fungus.
As you can see I am not optimistic about the use of vitamins for toenail fungus but these are a couple to consider.