Loss of Hair Pigmentation
A: As a part of the aging process, various cells throughout our bodies break down and slowly decrease production or simply stop functioning as intended.
The cells of our body are constantly being replicated and replacing themselves. This is what allows our bodies to heal and enables us to grow from infancy into adulthood. However, this process does not continue indefinitely at the same rate. As we age, many cells become less efficient at reproducing and repairing themselves, and some specialized cells eventually become damaged, depleted, or stop functioning altogether.
How Hair Follicles Produce Color
The cells in our body differ according to the function they serve. Dozens of cell types are found in the skin alone, each with a specific job. The health and activity of these cells directly affect the appearance and function of the tissues they support.Among these are the cells that make up the thousands of follicles that produce hair. Hair follicles contain specialized pigment-producing cells called melanocytes, which produce melanin: the pigment that gives our skin and hair its color.
Hair color is determined largely by the type and amount of melanin produced by melanocytes in an individual follicle:
• Eumelanin produces dark brown and black shades.
• Pheomelanin produces red and yellow shades.
This pigment is transferred into the growing hair shaft as the strand forms. The particular combination and amount of pigment produced is influenced by genetics, creating the wide range of natural hair colors found among humans.
The cellular breakdown associated with aging directly impacts this pigment system. Hair follicles rely on melanocyte stem cells to supply new, active melanocytes during each growth cycle. Over time, these stem cells become damaged, fail to self-renew, or become trapped in non-pigment-producing states. When a follicle lacks functional melanocytes, it ceases supplying melanin to the hair strand, causing new growth to appear white or transparent.
The Gradual Onset of Graying
This graying process does not happen simultaneously across all follicles. Individual hair follicles lose their pigment-producing ability at different rates, which is why the first signs of gray hair are often scattered strands among normally pigmented ones. Over time, more follicles produce hair with reduced melanin, and the overall hair appears increasingly gray. Eventually, a follicle may produce hair with no pigment at all, appearing completely white.An individual hair strand does not turn white after it emerges from the scalp. Once hair grows out of the follicle, it is a nonliving keratin structure. The visible color is determined entirely inside the follicle before the strand emerges. If the follicle stops supplying melanin to the newly forming shaft, the new growth simply lacks pigment.
The gradual decline in melanocyte function is a normal part of biological aging, but the timing varies considerably. Genetics plays the dominant role in determining when someone begins to gray, influencing genes that regulate melanin production and storage. This explains why some people develop their first gray hairs in their twenties, while others retain natural hair color well into late adulthood.
What we commonly refer to as "gray hair" is an optical illusion: a visual mixture of normally pigmented strands intermingled with white strands, rather than a distinct gray pigment being produced by the follicles.
Age-related Mechanisms
Several age-related mechanisms contribute to graying:• Oxidative Stress: As hair cells process energy, they generate reactive oxygen species. Over time, hydrogen peroxide naturally accumulates within the hair follicle. In younger follicles, enzymes like catalase break this down, but aging reduces catalase levels, allowing hydrogen peroxide to build up and essentially bleach the melanocytes from the inside out.
• Cellular Exhaustion: Repeated hair-growth cycles (anagen, catagen, and telogen phases) gradually wear out the stem cell reservoir in the follicle's bulge region.
• Environmental & Lifestyle Factors: Factors like smoking, severe stress, and nutritional deficiencies (such as Vitamin B12 or iron deficiency) can accelerate cellular damage and speed up pigment loss.
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See also:
Gray hair and age
Pigmentation Aberration
Why does gray/white hair turn brown when wet?