Why Hair Goes Gray

Graying hair is a telltale sign of aging. Rarely, it can happen to children and young people as well. Studies reveal that 40 years is the average age in which hair starts to change colors for American people. The exact causes of hair graying have not been conclusively proven yet. There are several streams of theories and hypotheses regarding hair graying. Many scientists believe that genetics is a major factor. The defect of premature graying of hair is usually transmitted to the next generation through genes.

Causes Of Hair Graying

One can broadly classify hair graying into two types. The first is obviously related to aging, while the second is related to some other specific causes that are almost always associated with some diseases and unhealthy conditions. Examples include malnutrition and diseases such as albinism, vitilago, Werner syndrome, and pernicious anemia. The graying caused by malnutrition can be reversed if the person starts taking food with sufficient nutritional content. External factors such as excessive smoking might also cause premature graying.

Scientists have been researching about the exact chemical or physiological process that takes place when the color of hair changes to gray. They have made great progress, but have not yet found the clinching evidence supporting any of the theories so far. There are two kinds of theories that have been endorsed by a large number of scientists. The first one is associated with the increasing hydrogen peroxide content in hair and the other is associated with the loss of melanocyte cells from hair. It is not known now whether these two phenomena are inter-related or they occur independently of each other.

Hydrogen Peroxide And Hair Graying

The latest research finding in this field is that a chain reaction triggered by the increasing quantity of hydrogen peroxide in hair follicles bleaches hair. This will eventually result in gray-colored hair. This happens when the quantity of an enzyme called catalase decreases in hair follicles. This enzyme decomposes hydrogen peroxide into its constituent elements. It has to be noted that hydrogen peroxide occurs naturally in hair.


If this enzyme is not present in sufficient quantity, a large portion of hydrogen peroxide will not be decomposed. The situation becomes worse in case other enzymes that control the activity of hydrogen peroxide are not present. In such cases, the excess quantity of hydrogen peroxide will trigger a chemical chain reaction that eventually causes hair graying. Scientists are hoping that if one manages to halt this chain reaction, graying can be prevented.

Loss Of Melanocytes And Hair Graying

Before the advent of the hydrogen peroxide theory, the most prominent theory about graying hair had been the melanocyte theory. Even now, many scientists believe that the lack of melanocytes can be a major reason for hair graying.

The basis of this theory is the fact that hair color is determined by a combination of certain types of cells called keratinocytes and some kinds of pigments. The pigments are manufactured by and stored in melanocyte cells. When the quantity of melanocyte cells decreases, the pigment production is affected, this in turn, affects the hair color. The lack of sufficient quantity of pigments imparts a gray color to hair.

What adds solidity to both the above-mentioned theories is the fact that the reduction in catalase and melanocyte is associated with aging. The function of melanocytes is impaired by aging process as well. Therefore, the theories succeed in explaining the hair-graying phenomenon associated with aging.


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