Damage to the hair can be self inflicted either by intentional or unintentional means. Some people going through stress continuously pull at their hair until it comes out. Styling hair by bleaching, braiding and straightening can also cause damage and results in hair being lost.
Overbrushing is one of the leading causes of mechanical damage to the hair.

Caring for Mechanically Damaged Hair
Brushing massages the scalp, helping to remove loose scales, and distributes sebum evenly through the hair, helping it to shine. However, over-brushing can make your hair greasy and may damage the hair and scalp. When brushing use a firm regular stroke, pull the brush through the hair close to the scalp in a smooth motion and repeat until the scalp feels warm and tingly. Do not brush hair when wet as it can break. Combing may help to untangle knots gently. Ensure that your brush and comb have smooth rounded bristles. Don't use metal combs and brushes, which can damage the hair cuticle.

Dietary changes for Damaged Hair
Since hair is made of protein you need a properly balanced diet to maintain hair growth. Your hair can't thrive without enough zinc, iron, magnesium, potassium and B complex vitamins. Be sure to eat plenty of fresh fruit and salad with protein sources such as lean meat, eggs and fish.