1 Calcium and vitamin D intake. 2  A diet low in calcium and vitamin D makes you more prone to bone loss. 3  Medication use. 4  Some medicines increase the risk of osteoporosis. 5  Activity level. 6  Lack of exercise or long-term bed rest can cause weak bones. 7  Smoking.
Signs and Symptoms. 1  Nail splitting affects the fingernails and the toenails. The condition may appear as a single horizontal split between layers of the nail plate at the growing end or as multiple splits and loosening of the growing edge of the nail plate.
4. Health Conditions. If your nails are brittle it may be a sign that you are getting an inadequate amount of oxygen to the feet, which can signal a respiratory issue such as asthma. Psoriasis can mimic the symptoms of a fungal infection in the toenails, causing them to become brittle or fall off. Hyperthyroidism or hypothyroidism can also cause the nails to split or separate easily. Dehydration, alopecia areata or eczema can also cause the nails to become brittle.