What are good vitamins to take for longer fingernails?

Biotin, a coenzyme and B vitamin also known as vitamin H, may help strengthen brittle nails, according to MedlinePlus. While biotin won't make nails grow faster, WebMD states that it may prevent nails from breaking.

Patients may see an improvement in nail strength by supplementing with 2.5 milligrams of biotin per day, according to a physician quoted by WebMD. In addition to supplementing with biotin, patients may protect nails by bringing their own tools to a nail salon, wearing gloves or directing a manicurist not to buff the nail surface before polishing, as that can cause the nail bed to thin or weaken.