Hair dye may almost double the risk of prostate cancer, according to a large prospective study from Finland.
The researchers tracked the health of 29,000 middle-aged male smokers over three decades, as part of a broader randomised controlled trial of the effects of vitamin E and beta-carotene on lung and other cancers.
In that time, 2703 participants were diagnosed with prostate cancer. Out of the total cohort, 75 reported using hair dye at the start of the study, and 13 of them were diagnosed with prostate cancer over the observation period.
After adjusting for confounders such as age, the number of cigarettes smoked daily, years of smoking and family history, researchers found that men who dyed their hair had almost twice the risk of being diagnosed with prostate cancer than those who were not using hair dye at the beginning of the study.
Fortunately, they did not find that baldness and grey hair put men at higher risk.
The link between hair dye and prostate cancer has been raised and disputed over many years. “Epidemiological investigations of hair dye use have for the most part focused on the risk of breast and bladder cancer and leukemia, with findings being inconsistent, and no prospective analysis has been conducted for the prostate cancer risk,” said the study’s authors.
Nevertheless, the study only involved a relatively small number of men who admitted to dyeing their hair. Furthermore, hair dye composition has changed since the study captured that data in 1985-1988, and the authors noted hair dyes used in Finland in the 1990s contained chemicals of concern. It was also not known how long men had been dyeing their hair prior to the study.