Often with brittle nails, the main culprit is simply a lack of moisture, just as dry skin can leave your epidermis cracked or flaky [source: Wadyka].
Regular moisturizers available at the drugstore, such as Vaseline, can help to keep nails healthy, while some people trust home remedies, like a mix of egg yolks and milk. There are also creams that seal in moisturizers, such as Aquaphor and Trind Nail Balsam.
Over the last decade, a class of creams called super moisturizers has become firmly entrenched in the nail care market. Applied to nails and the area surrounding them, super moisturizers are creams beefed up with vitamin E, avocado oil and shea butter.