From straight to curly, thick to thin: here’s how hormones and chemotherapy can change your hair
From puberty to pregnancy to chemotherapy, various factors can change the texture, thickness, and color of our hair. Hormones and genetics play a significant role in these transformations.
Head hair comes in many colours, shapes and sizes, and hairstyles are often an expression of personal style or cultural identity.
Many different genes determine our hair texture, thickness and colour. But some people’s hair changes around the time of puberty, pregnancy or after chemotherapy.
So, what can cause hair to become curlier, thicker, thinner or grey?
Curly or straight? How hair follicle shape plays a role
Hair is made of keratin, a strong and insoluble protein. Each hair strand grows from its own hair follicle that extends deep into the skin.
Curly hair forms due to asymmetry of both the hair follicle and the keratin in the hair.
Follicles that produce curly hair are asymmetrical and curved and lie at an angle to the surface of the skin. This kinks the hair as it first grows.
The asymmetry of the hair follicle also causes the keratin to bunch up on one side of the hair strand. This pulls parts of the hair strand closer together into a curl, which maintains the curl as the hair continues to grow.
Follicles that are symmetrical, round and perpendicular to the skin surface produce straight hair.
Mosterpiece/Shutterstock
Life changes, hair changes
Our hair undergoes repeated cycles throughout life, with different stages of growth and loss.
Each hair follicle contains stem cells, which multiply and grow into a hair strand.
Head hairs spend most of their time in the growth phase, which can last for several years. This is why head hair can grow so long.
Let’s look at the life of a single hair strand. After the growth phase is a transitional phase of about two weeks, where the hair strand stops growing. This is followed by a resting phase where the hair remains in the follicle for a few months before it naturally falls out.
The hair follicle remains in the skin and the stems cells grow a new hair to repeat the cycle.
Each hair on the scalp is replaced every three to five years.
Just Life/Shutterstock
Hormone changes during and after pregnancy alter the usual hair cycle
Many women notice their hair is thicker during pregnancy.
During pregnancy, high levels of oestrogen, progesterone and prolactin prolong the resting phase of the hair cycle. This means the hair stays in the hair follicle for longer, with less hair loss.
A drop in hormones a few months after delivery causes increased hair loss. This is due to all the hairs that remained in the resting phase during pregnancy falling out in a fairly synchronised way.
Hair can change around puberty, pregnancy or after chemotherapy
This is related to the genetics of hair shape, which is an example of incomplete dominance.
Incomplete dominance is when there is a middle version of a trait. For hair, we have curly hair and straight hair genes. But when someone has one curly hair gene and one straight hair gene, they can have wavy hair.
Hormonal changes that occur around puberty and pregnancy can affect the function of genes. This can cause the curly hair gene of someone with wavy hair to become more active. This can change their hair from wavy to curly.
Researchers have identified that activating specific genes can change hair in pigs from straight to curly.
Chemotherapy has very visible effects on hair. Chemotherapy kills rapidly dividing cells, including hair follicles, which causes hair loss. Chemotherapy can also have genetic effects that influence hair follicle shape. This can cause hair to regrow with a different shape for the first few cycles of hair regrowth.
Igor Ivakhno/Shutterstock
Hormonal changes as we age also affect our hair
Throughout life, thyroid hormones are essential for production of keratin. Low levels of thyroid hormones can cause dry and brittle hair.
Oestrogen and androgens also regulate hair growth and loss, particularly as we age.
Balding in males is due to higher levels of androgens. In particular, high dihydrotestosterone (sometimes shortened to DHT), which is produced in the body from testosterone, has a role in male pattern baldness.
Some women experience female pattern hair loss. This is caused by a combination of genetic factors plus lower levels of oestrogen and higher androgens after menopause. The hair follicles become smaller and smaller until they no longer produce hairs.
Reduced function of the cells that produce melanin (the pigment that gives our hair colour) is what causes greying.
Theresa Larkin, Associate professor of Medical Sciences, University of Wollongong
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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Stop Cancer 20 Years Ago
Dr. Jenn Simmons shares vital tips on preventing cancer and inflammation, advocating for lifestyle changes and proactive health management at any age.
Get Abreast And Keep Abreast
This is Dr. Jenn Simmons. Her specialization is integrative oncology, as she—then a breast cancer surgeon—got breast cancer, decided the system wasn’t nearly as good from the patients’ side of things as from the doctors’ side, and took to educate herself, and now others, on how things can be better.
What does she want us to know?
Start now
If you have breast cancer, the best time to start adjusting your lifestyle might be 20 years ago, but the second-best time is now. We realize our readers with breast cancer (or a history thereof) probably have indeed started already—all strength to you.
What this means for those of us without breast cancer (or a history therof) is: start now
Even if you don’t have a genetic risk factor, even if there’s no history of it in your family, there’s just no reason not to start now.
Start what, you ask? Taking away its roots. And how?
Inflammation as the root of cancer
To oversimplify: cancer occurs because an accidentally immortal cell replicates and replicates and replicates and takes any nearby resources to keep on going. While science doesn’t know all the details of how this happens, it is a factor of genetic mutation (itself a normal process, without which evolution would be impossible), something which in turn is accelerated by damage to the DNA. The damage to the DNA? That occurs (often as not) as a result of cellular oxidation. Cellular oxidation is far from the only genotoxic thing out there, and a lot of non-food “this thing causes cancer” warnings are usually about other kinds of genotoxicity. But cellular oxidation is a big one, and it’s one that we can fight vigorously with our lifestyle.
Because cellular oxidation and inflammation go hand-in-hand, reducing one tends to reduce the other. That’s why so often you’ll see in our Research Review Monday features, a line that goes something like:
“and now for those things that usually come together: antioxidant, anti-inflammatory, anticancer, and anti-aging”
So, fight inflammation now, and have a reduced risk of a lot of other woes later.
See: How to Prevent (or Reduce) Inflammation
Don’t settle for “normal”
People are told, correctly but not always helpfully, such things as:
- It’s normal to have less energy at your age
- It’s normal to have a weaker immune system at your age
- It’s normal to be at a higher risk of diabetes, heart disease, etc
…and many more. And these things are true! But that doesn’t mean we have to settle for them.
We can be all the way over on the healthy end of the distribution curve. We can do that!
(so can everyone else, given sufficient opportunity and resources, because health is not a zero-sum game)
If we’re going to get a cancer diagnosis, then our 60s are the decade where we’re most likely to get it. Earlier than that and the risk is extant but lower; later than that and technically the risk increases, but we probably got it already in our 60s.
So, if we be younger than 60, then now’s a good time to prepare to hit the ground running when we get there. And if we missed that chance, then again, the second-best time is now:
See: Focusing On Health In Our Sixties
Fast to live
Of course, anything can happen to anyone at any age (alas), but this is about the benefits of living a fasting lifestyle—that is to say, not just fasting for a 4-week health kick or something, but making it one’s “new normal” and just continuing it for life.
This doesn’t mean “never eat”, of course, but it does mean “practice intermittent fasting, if you can”—something that Dr. Simmons strongly advocates.
See: Intermittent Fasting: We Sort The Science From The Hype
While this calls back to the previous “fight inflammation”, it deserves its own mention here as a very specific way of fighting it.
It’s never too late
All of the advices that go before a cancer diagnosis, continue to stand afterwards too. There is no point of “well, I already have cancer, so what’s the harm in…?”
The harm in it after a diagnosis will be the same as the harm before. When it comes to lifestyle, preventing a cancer and preventing it from spreading are very much the same thing, which is also the same as shrinking it. Basically, if it’s anticancer, it’s anticancer, no matter whether it’s before, during, or after.
Dr. Simmons has seen too many patients get a diagnosis, and place their lives squarely in the hands of doctors, when doctors can only do so much.
Instead, Dr. Simmons recommends taking charge of your health as best you are able, today and onwards, no matter what. And that means two things:
- Knowing stuff
- Doing stuff
So it becomes our responsibility (and our lifeline) to educate ourselves, and take action accordingly.
Want to know more?
We recently reviewed her book, and heartily recommend it:
The Smart Woman’s Guide to Breast Cancer – by Dr. Jenn Simmons
Enjoy!