According to Ayurveda, hair is a by-product of the process of bone tissue formation. When the metabolism of this tissue, which is governed by your digestive fire (agni) is impaired, it can reflect poorly on the health of your hair. Pitta dosha, characterized by the elements of fire and water, is responsible for the digestive system and hormones that play a major role in hair health. Excess pitta can cause hair loss and premature graying. Overly sour, salty, and spicy foods can increase pitta, and so can hot weather or being short-tempered.
Hair has a programmed life cycle: a growth phase, rest phase and shedding phase.