The 50-50-50 Grey Hair Rule: Was it an overestimation?

Approximately 6-23 % of the World’s Population has 50 % of their Hair Grey by Age 50

There has long been a rule of sorts known as the 50-50-50 Rule. It states that by age 50, about 50 % of the caucasian population has 50 % of their hair grey.

Authors set out to evaluate if this is true or not. They evaluated 4192 healthy male and female volunteers through the comparison of each volunteer's hair with standard swatches. Hair colour was studied according to age, gender and ethnic or geographical origin.

Overall, the authors observed that between 45 and 65 years of age, 74% of people were affected by grey hair with a mean intensity of 27%. Men had significantly more grey hair than women. Both age at onset and rate of greying with age were closely linked to ethnic/geographical origin. Patients of Asian and African descent showed less grey hair overall than those of caucasian origin (at comparable ages). This is in keeping with prior data.

The authors calculated that the percentage of people showing at least 50% grey hair coverage at age 50 years leads to a global range of 6-23% rather than 50 %. The widely held view that 50% of the population has 50 % grey hair by age 50 seems to therefore be an overestimation.

REFERENCE

Panhard S et al. Greying of the human hair: a worldwide survey, revisiting the '50' rule of thumb. Br J Dermatol. 2012 Oct;167(4):865-73.