After it became apparent that biotin strengthens animal hooves, studies were performed on humans. The results of three separate trials, in which subjects were given 2.5 mg of biotin per day for up to six months, suggest that biotin may be an effective treatment for splitting, thin or brittle fingernails, according to the Linus Pauling Institute at Oregon State University. Biotin is found naturally in food, although supplements will provide higher levels. Talk to your physician if your nails don't improve.
Incorporate biotin-rich foods into your daily diet. Foods containing biotin include organ meats such as liver, egg yolks, whole grains and cereals, yeast, cauliflower, soybeans, fish, milk, lentils, soybeans, peanut butter, bananas and mushrooms.
Take daily biotin supplements if diet fails to strengthen your weak nails. Commercial biotin supplements are available in 10, 50 and 100 mcg doses, according to the University of Maryland Medical Center. The recommended dosage for adults is 30 mcg.
Talk to your physician or dermatologist if your nails are still weak or if you want to take a higher dosage of biotin. Research participants were given 2.5 mg of biotin per day, which is a high level that must be supervised by a physician, advises Health Services at Columbia University. Although biotin is believed to be non-toxic, there is potential for side effects and possible interactions with prescription medications.