Reader Questions: Hair Shedding

This question was emailed to me quite a while back by Alexis, here it is.............





I have a question. Can you do a post about shedding? I'm a member of various hair boards and a lot of the things people say about shedding just don't make sense to me. The problem is, I can't find any scientific information outside of "everyone sheds 50-100 hairs a day".





The main things I'd like addressed:





"I used X product (usually it's protein) and my shedding stopped completely"....I feel like that's impossible, even with garlic, because hair has to shed at some point. A related thing is "I stopped combing/brushing/using heat, etc. etc. and my hair stopped shedding, " or, "Now that I take care of my hair I never shed"...everybody sheds right?





I do think it is safe to assume that everybody sheds hair. Shedding is part of the normal hair growth cycle allowing a new hair to emerge from the follicle. Hair breakage is different from shedding and some hair products can stop breakage at least temporarily.





I don’t think hair shedding can entirely stop but some people do shed hair while it is still in the growing phase and this can sometimes be fixed with medication.





Alexis: How much shedding is "normal"? Is 50-100 per day the right range?





Actually the exact range is 34-180 per day. This figure comes from a mix of scientific studies, the exception to the rule are Thai women who have a very low range of shedding at 28-35 hairs per day.





The range you quoted is often accepted widely by scientists and actually comes from maths. It is estimated than on average we have about 100,000 individual hairs on the scalp. It is then calculated that a vast majority 85-90% of these are in the growing stage (known as anagen). Therefore approximately 10% of hair is in the resting or shedding phase. Then estimate the amount of hair actually shedding and you get 1 in every 1000 hairs in total. For a head of 100,000 hairs you get that magic number 100 hairs per day. (Journal of the Society of Cosmetic Chemists, pg 195-206, 1992)





Alexis: Is there a such thing as seasonal shedding?





Yes this does exist but it is quite varied. Some people have it and some don’t. Also the patterns don’t necessarily follow the same trend. One study reported seasonal shedding among some men with most hair fall at the end of summer and the beginning of autumn. (British Journal of Dermatology, pg 47-54, 2008).





Another interesting fact is that pregnancy can reduce hair shedding dramatically because the hormone combination is thought to prolong the growing phase of hair. This can push down shedding to as low as 15-20 hairs per day. (Journal of the Society of Cosmetic Chemists, pg 195-206, 1992)