As per Ayurveda greying of hair is called palitya and hairfall is known as khalitya, which occurs due to the imbalance of Pitta dosha. So you should avoid the diets and lifestyle that increase your pitta dosha. The other factors like low levels of iron, folic acid and Vitamin B12, prolonged periods of stress and anxiety can and also lead to premature graying and hair fall. 

Dietary and Lifestyle modification : 

•  Avoid excessive use of pungent, sour, salt and fried food items.
• Avoid refined sugar, refined foods, junk food and carbonated drinks.
• Increase intake of green leafy vegetables, fresh fruits, poultry, eggs, milk, walnuts, broccoli and seafood in your diet.
• Practice yoga regularly and include asanas like Kapalabhati, Sarvangasana, Sirsasana, Vajrasana as these reduce your stress levels and promote healthy hair growth by increasing the blood circulation.

Remedies :

1. Take a handful of curry leaves and boil it in 1 cup of coconut oil for six to eight minutes.Allow it to cool and massage your scalp with this mixture once a week.

2.Warm up some Kalonji seed oil and massage the hair and scalp thoroughly with it. Keep it overnight and wash with milk herbal shampoo.Do this 1-2 times in a week.