TLDR White hair grows thicker and faster than black hair due to higher activity of growth-related genes and proteins.
The study from over a decade ago found that white hair is not only thicker and grows faster than black hair, but also exhibits a higher expression of genes and proteins related to active hair growth. Specifically, keratin and keratin-associated protein (KRTAP) genes, especially KRTAP4 isoforms, were significantly upregulated in white hair. Additionally, immunoreactivity for keratins KRT6, KRT14/16, and KRT25 was increased in the hair follicle of white hair. The study also noted a downregulation of fibroblast growth factor 5 (FGF5), which inhibits hair growth, and an upregulation of FGF7, which promotes hair growth, in white hair. These results suggest that the process of hair greying may be linked to an increase in hair growth activity. The number of participants or hair samples analyzed was not specified in the study.
56 citations,
November 2010 in “Pigment Cell & Melanoma Research” Brain hormones significantly affect hair color and could potentially be used to prevent or reverse grey hair.
17 citations,
October 2010 in “Pigment cell & melanoma research” Human hair color is influenced by complex biochemical processes involving enzymes and reactive oxygen species.
45 citations,
July 2009 in “Journal of human genetics” A gene variation is linked to hair thickness in Asians.
138 citations,
March 2007 in “Experimental cell research” Only a few hair-specific keratins are linked to inherited hair disorders.
210 citations,
May 2006 in “The FASEB journal” Oxidative stress causes hair to gray by damaging and killing pigment cells.
71 citations,
August 2005 in “The journal of investigative dermatology. Symposium proceedings/The Journal of investigative dermatology symposium proceedings” Hair keratin-associated proteins are essential for strong hair, with over 80 genes showing specific patterns and variations among people.
27 citations,
June 2005 in “The journal of investigative dermatology/Journal of investigative dermatology” The study found that variations in hair protein genes are likely due to evolutionary deletions or duplications.
24 citations,
November 2013 in “Trends in pharmacological sciences” Increasing ABC transporters in hair follicles may prevent chemotherapy-induced hair loss.
