Most "Hair Loss" People See Is Shedding, Not Breakage, Global Study Finds

A new data analysis published in the International Journal of Cosmetic Science pins down something hair care marketing has long left vague: most of what people collect in the shower or on a brush is not breakage at all. Researchers led by Yingjie Li and colleagues at what appears to be an industry-academic collaboration pooled data from 12 clinical studies spanning 805 participants across eight countries, then took a close look at two recent Chinese studies and one Indonesian study to separate hairs shed from the root from hairs that simply broke.

The distinction matters because the two have different causes and, by extension, call for different product responses. Shed hairs come out with a club-shaped root end, marking the natural end of a hair's growth cycle, while broken hairs snap partway along the shaft, often from mechanical or chemical stress. The analysis found root-shed hairs made up 96.5% of total hair fall in Chinese female participants, 98.8% in Chinese male participants, and 72.2% in Indonesian female participants. A review of nine older clinical studies from other regions backed up the pattern, with shed-hair proportions ranging from 67.1% to 97.7% regardless of geography or gender.

The researchers also traced when hair actually comes out. Mining data from the two Chinese studies, they found washing accounted for the largest share of hair loss, 49.6% in women and 74.1% in men, with drying and post-dry combing trailing behind. That sequencing is a useful fact for anyone evaluating a shampoo or conditioner claim: a product marketed around reducing shedding is, per this dataset, largely being judged on what happens during the wash step itself, not on daily wear.

Age also showed up as a measurable factor, but only on one side of the gender line. Using Spearman correlation analysis, the authors found hair shedding increased with age in female participants. A follow-up comparison using the Mann-Whitney U test split women into a younger group (18 to 42 years) and an older group (over 42), and again found more shedding in the older cohort. The paper does not report the same age effect for men, a gap that leaves an open question for any product positioning aimed at hair-thinning concerns across a general adult audience rather than one calibrated to sex and age.