Marvelous things, fingernails. They protect the ends of the fingers, help make fingertips more sensitive to touch, provide a handy device for scratching, and in emergencies, double as letter openers, staple removers, and even tiny screwdrivers. In addition to their functional aspects, fingernails can become objects of adornment, taking on whatever color or decoration (including precious metal and gemstones) suits the occasion.
Human nails, like human hair, are made up of a tough protein called keratin. The nail plate on top of the finger is formed from the nail matrix, a special group of cells under the base of the nail near the cuticle. Part of this matrix is visible on the larger nails as the white moon (lunula) just past the cuticle.
The nail plate is translucent. The pink color of normal nails comes from the blood in the nail bed on which the plate rests. The nail plate is kept on the straight and narrow by folds of skin on the two sides and at its base. Without these folds the nails would grow straight up.
Technically, since it does not contain living cells, the nail plate is not alive. Yet it grows continually at a speed of about three millimetres—an eighth of an inch—a month. It takes five to six months to grow a new fingernail. For reasons unknown, the nail on the middle finger grows the fastest, while those on the little finger and the thumb grow the slowest. If nails didn’t break from such mundane tasks as dialing telephones, typing and housework, they could conceivably grow as long as . . . well, very long.
(The longest nails on record, according to the 1985 Guiness Book of Records, belong to Shridhar Chillal of Poona, India. As of April 1984, the curving nails on his left hand together measured 135 inches—more than 11 feet.)
Pregnancy or an excess of thyroid hormone speeds up nail growth. Psoriasis, a skin disease that speeds the growth of skin cells, also makes nails grow faster. Nails grow faster in warm weather and when they are recovering from an injury.
In contrast, advancing age, cold weather, malnutrition, and illness can slow and even stop nail growth. A tell-tale sign that a person has suffered a serious illness or had major surgery is a thin groove from side to side across the nail plate, called a “beau’s line,” after a 19th century French physician. The position on the nails is a clue to when the illness occurred.
Nails provide other indications that their owner is or has been ill. For instance, an opaque or white nail could signal cirrhosis of the liver; a nail that is red at the tip but white across the base could indicate chronic kidney disease. Besides making the nails grow faster, psoriasis may cause yellowing and little round pits in the nail plate. It also may cause the nail to separate from the nail bed, as will an overactive thyroid.
Vertical ridges—from base to tip—may be a sign of Raynaud’s disease (a circulatory disorder), rheumatoid arthritis, or lichen planus, an inflammatory skin disease.
Brittle nails may result from age, anemia or poor circulation, but the most common culprit is water. Nails are never as tough as they look; in fact they are actually permeable—water and solvents can pass through them. When they are immersed in water the nails swell; out of water they dry out and shrink. Frequent swelling and shrinking damages the structure of the nail, causing it to break easily.
Changes in nails, can occur when an individual is exposed to chemicals—of the medicinal variety or otherwise. Discoloration and separation of the nails have been reported as unusual side effects of long-term use of tetracycline. Nail changes, including loss of the nail, also have been associated with cancer drugs. An excess of copper or silver in the body turns the nails blue. Too little iron in the system can lead to a spoon-shaped nail—one whose sides curve up instead of down over the finger. Arsenic, which has a particular attraction to keratin, can be detected by white hands on the nails.
Some chemicals used in agriculture—paraquat, diquat and dinitro-orthocreosol—have caused loosening and discoloration of nails in persons exposed to these substances.
Nail polishes, used to beautify and protect the nails, may also produce some unpleasant side effects, such as brittle nails and allergic reactions involving the nails themselves, as well as other parts of the body touched by the polished nail. FDA requires that the ingredients in nail polishes and other cosmetics be listed on the product label so that consumers can avoid ingredients that cause them problems.
Some nail abnormalities result from injuries such as pressure put on the nail plate during manicure or a misdirected hammer blow. Nail are also subject to their own diseases principally ringworm of the nails, called time unguim, include green discoloration of yellowing of the ends of the nails and nail fold and a lifting of the nail plate. Because these symptoms are also associated with psoriasis an accurate diagnosis is important.
The prescription drug griseofulvin (trade names Fulvicin, Grifulvin V and Grisactin) is the cornerstone for treatment of ringworm, but full recovery takes four to six months. Over-the-counter drugs containing anti-fungal ingredients are not usually effective in treating this nail disorder.
Warts are hard to treat for a number of reasons. For instance, they may exist in in apparently healthy tissue surrounding the nail or extend far below the surface. The patient with many warts is probably a nail biter whose nibbling spreads the infection.
Freezing with liquid nitrogen is a common treatment for warts around the nails. Others are topical catharidin (a prescription drug) or salicylic acid (an over-the-counter product). Surgery is sometimes necessary, but it can be tricky because of the danger of distorting the nail structure.
While some insults to the nails can’t always be avoided, many can be prevented by common-sense nail care. For instance, wearing protective gloves while doing household and gardening chores will prevent overexposure to water, harsh chemicals, and microorganisms that live in the soil. Nails should be kept neatly manicured, using cosmetics judiciously. Nail polish should not be removed too often, as some polish removers may be harsh and can dry and irritate the nails. It is best to keep polish on for five or six days, then remove it, and wait a day or two to reapply.
While malnutrition may have an effect on nails—experts agree that there is no magic diet to improve them. Some years ago many women fell prey to the myth that eating plain gelatine would give them beautiful nails. There is no scientific evidence that it does.
The best advice is to eat a well-balanced diet to maintain optimum overall health. Then the nails will take care of themselves.