Several nail-care products want you to believe that “What’s good for your teeth is great for your nails,” so you can “Harness the power of fluoride with strengtheners, base and top coats, and cuticle care.” If only that were possible! It would be a dream come true to have a product that could make nails as strong as teeth, or even relatively as strong. Alas, unless you were born with naturally strong nails, fluoride isn’t going to help your nails the way it helps teeth.
First, teeth are unrelated to nails. Teeth are made of a bony substance composed of various mineral compounds, mostly calcium phosphate. Nails have no mineral content but rather are composed of hardened keratin, basically the same substance that comprises skin and hair. Further, fluoride doesn’t “strengthen” teeth, but rather, according to the American Dental Association, has varying influences that work with saliva and the growth of developing teeth to prevent decay. One function of fluoride is to reduce the constant reaction taking place between the tooth’s surface, saliva, and bacteria in the mouth. When we eat sugar or starchy foods the number of bacteria in the mouth increases, which raises the acidity of our saliva, which in turn slowly, over time, demineralizes the surface of the tooth. As the acidity subsides, the tooth’s surface becomes remineralized. Fluoride reduces the presence of bacteria in the mouth, which reduces the acidity of the saliva and in turn reduces or eliminates tooth decay. None of that, to put it mildly, has anything to do with nail growth or nail problems.
One more point: Given that almost all of us drink and wash with fluoridated water, our nails are consistently exposed to fluoride. If fluoride were important for healthy nails—which it isn’t—the amount we get in our drinking water would be more than enough.
The nail-care industry has tried to build up many ingredients in the effort to convince us that we can grow stronger nails. For years protein was a big one that showed up in nail-care products, though protein can’t feed the skin or nail from the outside in. Diligently applying most nail-care products does help, but it is the protective coating they provide that does the trick, not these impressive-sounding-yet-do-nothing special ingredients.