What is dandruff and why do I have more of it than my friends? I can’t wear any dark shirt without snow on my shoulders. What can I do about it? Please help me understand what is happening to my scalp!
Skin is not static. It changes and we shed it like a snake sheds its skin, but we do this a little each and every hour of the day. In two weeks, the average person will shed their entire skin surface and replace it with new skin. Scalp skin takes about a month to turn over, so the process is a bit longer. To understand dandruff, let’s take a quick look at psoriasis. “Psoriasis is a skin disease that causes scaling and swelling. Skin cells grow deep in the skin and slowly rise to the surface. This process is called cell turnover, and it normally takes about a month. With psoriasis, it can happen in just a few days because the cells rise too fast and pile up on the surface.” (source: NIAMS). Dandruff is like psoriasis in that the skin turnover is faster than normal (not anything as fast as psoriasis) and before it can be shed, it cakes up to form the flakes that you are observing and complaining about (dandruff).
Skin on different parts of the body shed at different rates and as we age, it is the genes in our body that determine how quickly the normal aging process occurs in our skin and the turnover rate of that skin for our age. The rate of aging and the daily changes in our skin can be influenced by extrinsic factors that can act together with the normal aging process to prematurely age our skin. Sun exposure is one of the most important factors that cause our skin to age but the way we use our body also impacts us. Exposure to varying environments will change the rate of skin turnover as well as the moisture that our skin has in it. Other external factors include things we do, like smoking, which has a duel effect, not only aging the skin and changing the water content of our skin, but it also decreases blood flow to some part of our skin anatomy (scalp). Over time, exposure to the sun damages our skin and impacts our ability to repair itself. Much of the damage is probably related to our exposure to ultraviolet (UV) light which damages our skin’s ability to repair itself. The skin which envelops our body becomes loose as we age and this process is accelerated when we do not protect our skin from sun exposure. The rate of skin turnover varies between people and dandruff is probably a reflection of the rate of skin turnover of our scalp skin for the flakes of dandruff are actually pieces of our skin which are shed prematurely. The higher the turnover rate, the worse the dandruff and the more frequent will be our complaints (e.g. itching, dryness) which plagues many of us.
The best way to manage your skin is to develop a sensible skin care routine. The scalp is no different. The use of moisturizers will soften and wet our skin; conditioners made for dry skin and dry hair will help restore moisture that is lost from the shampoos we use, which remove many of the protecting oils made by our sebaceous glands (sebum) that are designed to hold in moisture. Most important of all is the way you protect your skin from sun exposure, which can produce structural changes in your skin that are permanent. Older skin does not hold on to water very well, so older skin dries easily. Our outer skin layer (stratum corneum) may shed less as we age and the normal texture of the skin changes to reflect the loss of the supporting structures below the top skin layer. An older person’s skin appears dry and crinkly and this reflects a slowing down of collagen production as well as the fibrous elements that we call elastin. Elastin brings the recoil that returns the skin back to its normal position if we pull on it. In the typical aging person, the skin does not recoil very well when pulled upon and as such, it stands up after being pulled upon and it is also more fragile to injuries and environmental factors. Aging is a continuous process that normally begins in our mid-20s when most of our skin is healthy and hopefully not yet damaged by environmental factors. Dead skin cells do not shed as quickly and turnover of new skin cells will decrease as we age. The signs of aging are typically not visible for decades and this reflect the fact that our skin can take considerable abuse before it shows its age.
The dandruff on your head reflects many of the elements discussed above and the scalp skin is constantly exposed to drying from air and UV exposure, building up more damage over time.
Our body’s ability to replace itself varies significantly by body part and organ. For example, the outer layer of our skin completely replaces itself in about 2 weeks (scalp 4 weeks), while the lining in our intestine does it every 5 days. Our red blood cells replace themselves every 4 months (about 1/120th per day) and our bones about 10 years. Our chest muscles last 15 years, and our brains, well the part of it reading this blog, is as old as you are. So next time you get frustrated over the dandruff, think about what you have learned here, as it is a lot easier to moisturize and protect your scalp skin from sun damage than to simply ignore it as most of you do now.