Baking soda is not fungicidal-that is, it does not kill the fungus. It is, however, fungistatic, which means it can prevent fungus from growing and spreading. The reason it acts like this is because it is alkaline-the opposite of acidic-and fungus is able to flourish when its environment is more acidic. It seems counter-intuitive then, that using vinegar to kill nail fungus would be a good idea, but vinegar is a fairly weak acid, and will help kill off the fungus without altering the Ph. of the environment in a harmful way.
The much-touted ability of ozonated oils, such as olive oil or sunflower oil, to render fungus, yeast, and bacteria inactive has been common knowledge for centuries. These oils are produced by reacting ozone (O3) with oil, and they contain compounds with significant medicinal effects that are responsible for their success against toenail fungus.(5)(6)