Your fingernails — composed of laminated layers of a protein called keratin — grow from the area at the base of the nail under your cuticle. Healthy fingernails are smooth, without pits or grooves. They're uniform in color and consistency and free of spots or discoloration.
Sometimes fingernails develop harmless vertical ridges that run from the cuticle to the tip of the nail. Vertical ridges tend to become more prominent with age. Fingernails can also develop white lines or spots due to injury, but these eventually grow out with the nail.
It’s time for medical attention if you notice changes in nail color, such as discoloration of the entire nail or a dark streak under the nail. Other possible concerns include thinning or thickening of the nails or pain or swelling.
Don’t use harsh nail care products. Limit your use of nail polish remover. When using nail polish remover, opt for an acetone-free formula.
Some research suggests that the nutritional supplement biotin might help strengthen weak or brittle fingernails. There is anecdotal evidence that prenatal vitamins are helpful in growing healthy hair and nails.
If you rely on manicures or pedicures for healthy looking nails, keep a few things in mind. Stick to salons that display a current state license, and work only with technicians also licensed by the state board. Don't have your cuticles removed — it can lead to nail infection. Also, make sure your nail technician properly sterilizes all tools used during your procedure to prevent the spread of infection.
You might also ask how the foot baths are cleaned. Ideally, a bleach solution is used between clients and the filters are cleaned regularly.
Tips from the American Academy of Dermatology.