The theory that high levels of hydrogen peroxide in the hair follicle is at the root of gray hair is not new; however, proof was scarce and there was little understanding of the mechanism until now, according to the European researchers.
High levels of hydrogen peroxide
The team, led by Professor Schallreuter from Bradford University, UK, illustrated that in gray hair follicles hydrogen peroxide levels are much higher than in normal hair.
Although the reasons behind these increased levels are not known, the researchers have investigated their effects on important proteins involved in the formation of hair color.
Tyrosinase is an enzyme involved in the formation of hair color and high levels of hydrogen peroxide oxidise methionine (one of the amino acids that make up the enzyme). This change inactivates the enzyme which will lead to a lack of pigment in the hair.
The oxidation of the methionine would under normal circumstances be repaired by two methionine sulfoxide reductases called MSRA and MSRB and the tyrosinase would return to normal function.
However, the high levels of hydrogen peroxide also inactivate these enzymes, explained the researchers.
Furthermore, high hydrogen peroxide levels inactive another protective mechanism, the enzyme catalase.
According to Schallreuter, this enzyme would normally break down hydrogen peroxide into water and oxygen, but when inactivated it cannot, leading to even higher hydrogen peroxide levels.
Adding methionine may help
However, the team noticed that adding unbound L-methionine into the system, can prevent the inhibition of tyrosinase by hydrogen peroxide, perhaps opening up a path to stop or reverse graying hair.
Exactly how the free L-methionine can help, and how it could be administered, is under research at the moment, explained Schallreuter
“We know that it is not possible to get high enough levels of this amino acid through the diet,” she said.
Schallreuter and the team drew parallels with the skin depigmentation disorder vitiligo in which the role of hydrogen peroxide is well known.
“We can already reduce these levels in the skin, but not yet in the hair. Our current research is focusing on how we can influence this system,” she added.