To be precise, rubbing nails for near about 5 minutes, twice daily is pretty effective in prevention of grey hair. For those who don't believe, yes it is true; rubbing nails on your left hand with nails on your right hand is a beautifully simple solution for people having the problem of grey hair. This side effect free method consumes a small amount of time and its effects are remarkable. It helps in improving blood circulation through the scalp and imparts strength to hair roots. Although this method requires time and patience; it is still then a remarkably effective method popularized by the Ayurveda experts.