1. Taking too much stress a chemical norepinephrine is released in our body which spreads throughout our body and affects our follicles and stops pigmentation and the hair starts turning grey.
2.Please stop smoking, because a harmful toxic chemical is found in people who smoke, called as nicotine. It greatly affects the melanin production in our follicles, due to which the hair starts turning grey.
3. Genetics is also responsible to some extent for this.
4. Not eating enough nutritional food and vitamins also causes a lot of problems, if your body is deficient in essential vitamins like calcium, vitamin b6, vitamin E, D, or vitamin b12
some effective ways to prevent this
use onion juice, yes it is a great remedy to prevent grey hair, onion juice completely stops the formation of hydrogen peroxide in our body and it is also very effective.
Massage with coconut oil, massage your head with coconut oil at least two to three times every week
Using black seed is considered very effective, which prevents graying of hair to a great extent because linoleic acid is present in it which prevents the lack of pigments in our head
You can also use a mixture of rosemary and sage, both help in turning the hair black.