I'm in my fifties now but experienced major hair loss from my late 20's to my early forties. After a lot of research (supplements, OTC treatments, doctors, naturopaths, articles) I came to realize that hair fall for most men and women comes from the after affects of Candida and leaky gut syndrome. Sugar of all types (even fruits) accelerates it. The candida/leaky gut comes from too many antibiotics and not enough Probiotics to clean up the mess that they leave and/or simply eating very poorly and causing bacteria proliferation in different pockets in the gut over a period of years.
Try this if you're losing hair in the shower-
FAST for 24 -48 hours on water or broth. NO SUGAR. If your hairfall diminishes significantly or completely then your answer is there.