Hormones and Vitamins play an important role in the Hair growth. Hair consists of a pigment called "Melanin" which also occurs in the skin of human beings. This pigment is responsible for the dark nature of the skin and hair. In Young people, hair has large number of melanin pigments which leads to Dark nature of the hair and with the increase of the age, the no. of melanin pigments decreases, leading to whitening of the hair in old People. In older people, the follicles produce thin and long hair, and also sometimes also do not produce any hair. This is the cause for the Baldness in old people.

Alcohol effects hair growth, i.e. Alcoholics have poor hair growth or they experience hair loss due to malnutrition.
The Essential mineral for the growth hair is - Zinc (Zn) which is responsible for hair growth and also prevents hair from becoming Greyish in nature. Hormones and vitamins also have an essential role in hair growth -
Androgens are helpful in hair growth and also helps in Strengthening of Hair Shaft but are present in different ratio in men and women.

The Female hormones called Oestrogens decreases the growth of hair during the growth of the individual. During Pregnancy there is difference in hair growth as blood cntains more amount of Oestrogens at that time.

The effect of Androgens in male is different in many people, that is the reason some people do not get beard and hair on the chest upto a certain age of above 25 and a few get at an age of near 20.
Vitamin B - Panthenol Helps in maintaining the growth of hair and also contributes to the elastic nature and strength of the hair. Steroids taken by Asthma patients through inhalation does not effect the hair growth, but if taken orally, will slow down the hair growth.

Finally, Hormones are genetically produced and are determined and they help in growth of the hair.