What do the cracked hooves of racehorses have to do with brittle nails in humans? Believe it or not, there is a connection. Both the cracking of a horse’s hoof and brittle nails are attributed to dryness and dehydration of the protein keratin which is what hooves and nails are made of. There is another connection – both can be treated successfully with biotin supplements.

When thoroughbred racehorses develop cracked hooves, they cannot race; the approach taken by veterinarians and farriers (those who watch over these prized competitors) to remedy the problem is to feed them large doses of biotin. This treatment, which veterinarians have used since the mid-1980s, is successful in healing the cracked hooves so that the horses can race again. A group of researchers in Switzerland reasoned that if biotin repaired cracked hooves, it might also have a positive effect on brittle human nails. They set out to study the effect biotin supplements would have on women with brittle nail problems.

The study tested 32 women: a control group of 10 women with normal nails, a second group of eight women with brittle nails before and after being treated with biotin supplements, and a third group of 14 women who were administered biotin irregularly throughout the study. The biotin dosage was 2.5 mg. daily for at least six months and for as long as 15 months. Both researchers and subjects found the results impressive; the thickness of the nails in the second group of women increased up to 25%, and splitting of the nails was reduced. Thickness of he nails in the third group was increased by 7%, and splitting was reduced as well.

After these investigators published their data in 1990 in the Journal of the American Academy of Dermatology, the nail research center at Columbia University, under my direction, in New York City set out to do its own study in a similar population. We were able to confirm their results in two out of three patients, a somewhat lower success rate than what was described in the Swiss data, but nevertheless impressive.

Biotin is one of the minor B vitamins whose function has not been entirely evaluated. It is found in most multivitamin preparations, but only in minute quantities. Foods containing biotin include eggs and organ meats legumes, cauliflower, broccoli, and mushrooms. How biotin works on brittle nails and cracked hooves is unknown. It appears to be safe, with no side effects and is available without a prescription from health-food stores and pharmacies. However, since its effectiveness is dependent on very high doses to work, it would be prudent to check with one’s physician prior to starting biotin treatment.

A nail technician can recommend biotin but should refer clients to a doctor for appropriate dosage. For a benefit to nails, the vitamin is taken on a daily basis. Usually a minimum of 6-8 weeks must go by before improvement is noticed. Because of the high dosage requirement, it is definitely not advisable to take biotin during pregnancy until more is known about the vitamin; your client should at least consult with her obstetrician. About 20% of the female population is affected with brittle nails. Since this disorder – the so-called brittle nail syndrome – is due to moisture loss in the nail plate, it is best treated by rehydration. Soaking the nails at night in warm water for about 10 minutes and applying a good moisturizer will help retain moisture and improve their texture. Using formaldehyde-free enamels and acetone-free remover is also beneficial. Women with brittle nails should avoid excessive use of soap and water, contact with harsh detergents, and exposure to caustic cleaning agents. The nails should be filed toward the center bilaterally rather than from side to side, which can increase tearing. In sum, our nails should always be treated with respect and handled with care, brittle or not.


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