According to New York University's Langone Medical Center, thin or brittle nails are a problem for around 20 percent of people, although it's more common in women than men. Thinning of the nails can be caused by infection, over-exposure to water or cleaning products or just general mistreatment of your nails. There are certain things you can do to thicken your nails and improve their general quality.

Take 2.5 mg of biotin supplement each day. Preliminary studies have shown it to thicken the nails.

Eat a healthy diet full of fruit and vegetables. This will only help if you're currently deficient in any nutrients, which some people are without realizing.

Avoid picking at your cuticles or biting off hangnails. This can cause an infection, which will make your nails thinner and more brittle. Healthy nails are naturally thicker.

Wear rubber gloves for doing the dishes, cleaning and for any other activity where you'll have you hands submerged in water for a long period of time. Keeping your nails clean and dry will make them thicker.