The graying of hair, the age-related exhaustion of the pigmentary potential, is thought to be mainly genetic,

with a family history of premature graying present in up to 90 percent of cases. But if the rate of graying is caused by oxidative

damage, as I described in the last video, what role might be played by antioxidants

and systemic oxidative stress outside of the hair follicle? Those with premature grang

do seem to have higher circulating markers of oxidative damage

and lower antioxidant levels in blood.

The higher prevalence of premature graying among smokers also supports this possibility that

exogenous free radicals may speed up the accumulation of oxidative insults in the aging hair follicle.

Obeses individuals also tend to gray early, consistent with the oxidative stress concept,

though drinkers do not. Alcohol consumption clearly causes oxidative stress, yet is not

significantly associated with premature graying.

Those trying to maximize their intake of antioxidants by eating plant-based must deal with the

Achilles heel, the risk of vitamin B12 deficiency for those not actively supplementing their

diets with B12, whether from supplements or fortified foods,

B12 deficiency is one of the rare reversible causes of hair graying through some unknown mechanism.

Thankfully, hair can repigment after B12 repletion.

Another reversible cause is hypothyroidism, which can be reversed with thyroid hormone replacement.

Rather than oxidative stress, what about regular stress?

Does fight or flight turn hair white?

Marie Antoinette syndrome refers to the rapid graying of hair due to stress or trauma,

based on the likely apocryphal story of her hair going completely white on the eve of her

beheading.

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