Trauma to the nail bed (slamming it in the car door), excessive stress to the nails (think acrylics and frequent polish changes), and other damage can cause brittle nails. Bad Habits. Smoking, excessive alcohol consumption and biting the nails all can cause weak, brittle nails. Aging. As we age, the fingernail also ages. The aging process causes lack of collagen and keratin, a decrease in moisture, and dull, yellowish nails.
White flaky nails