Several Factors Contribute to Dry Hair Issues

Happy Fall! Depending on where you are, the air is crisp, the leaves are changing, sweaters are required and the sun is still shining. With the change in seasons comes a change in climate, reduced humidity, and that centralized forced air that keeps your home warm is drying out your skin. Well, what about your hair? We all know what dry hair feels like, but what is actually going on in there?

Dry hair can be the result of internal factors, environmental factors or grooming practices. Hair is rooted in the scalp, which is a part of the skin. A dry, flaky scalp cannot produce healthy hair. Maybe the scalp’s sebaceous glands are not producing enough oil or sebum. Sebum travels down the hair shaft to protect the hair from damage and provide natural shine.1 This may be the result of taking oral isotretinoin (formerly Accutane), which works by shrinking the sebaceous gland in the skin—excellent for treating acne, but not so great for hair. Remember—your scalp is skin. Maybe you have really curly, coiled, or kinky hair. If this is the case, because your hair is so curly, it is not sufficiently bathed by sebum as it grows and exits the scalp, leaving your hair dry, when compared to straight hair that is coated with oil and may become oily. This is why coily or tightly curled hair types do not get as oily, even if they wash their hair less frequently.

So, let’s talk about what is going on inside. Dermatology is the study of skin, hair, and nails—and skin is not good at keeping secrets. It reveals what is going on inside. So, what may dry hair be saying? Dry, lusterless hair can be a sign of hypothyroidism, reduced estrogen with age and vitamin deficiencies. These vitamin deficiencies may be a result of a poor diet or a serious eating disorder such as anorexia nervosa or bulimia. Some medications can also cause dry hair and even hair loss. For example, statins, a type of cholesterol-lowering medication, can make skin more porous, allowing more water to escape, which in turn dries skin. The scalp is skin and the hair cuticle is partly composed of cholesterol. This is no reason to stop prescribed medication, just moisturize your hair well.  

Now let’s talk about what we, as humans do every day that causes us to lose the moisture in our hair. This topic is too big to cover in one column, so this is a short synopsis of the top three—color, relaxer, heat.

Cuticle Questions
This section is all about the cuticle. The cuticle is the outermost part of the hair shaft and is composed of keratin (just as your skin and nails are). It protects the hair cortex, which is what gives hair its strength and color, from chemicals, water and weathering (such as pollution or climate). I like to think of the cuticle as shingles on a roof. Shingles must be tightly interconnected to avoid having a leaky roof. A healthy, intact cuticle is smooth, with low friction, giving hair its shiny appearance. The outer aspect of the cuticle contains fatty acids, ceramides, and cholesterol, like your skin—notice the recurring theme?

Permanent hair dyes containing paraphenyenediamine (PPD) or ammonia are alkaline, as are hair relaxers. These processes cause lifting of the cuticle by damaging the disulfide bonds, so that the chemicals may enter the cortex causing color change and straightening, respectively. Hair coloring and bleaching can lead to fiber swelling, cuticle detachment and complete exposure of the cortex.¹ Bleached hair is more porous, so it is different in texture, vulnerable to humidity, may appear dull and is in great need of moisture. Poor hair shaft! The damage is even worse in hair that has been chemically-treated and colored.

Thermal styling or thermal straightening with the use of blow dryers, flat irons, curling irons and the pressing comb disrupt the protein linkages that that maintain the strength of the hair shaft. Healthy hair burns at 451.4°F, while previously damaged hair burns at lower temperatures.1 When the cuticle is exposed to high temperatures, damage occurs in the form of splitting, cracking or peeling of the cuticle, bubble hair, and subsequent breakage. Bubble hair was first described by Dr. Len Sperling as a result of blow drying. Heat causes the expulsion of water, in the form of vapor, from the cortex and cuticle. Microscopic holes are left in the cuticle, leaving the hair fragile and susceptible to breakage.

Hair care faux pas that often contribute to dry hair include:

• Washing hair too often. Daily shampooing can rob hair of its protective oils and lead to dryness. Try washing your hair once or twice a week instead. You can also apply hair oils or leave-in conditioners to add luster and softness.
• Using harsh shampoos, conditioners or styling products. Some dandruff shampoos such as ketoconazole (Nizoral) increase the charges on the hair, causing dry hair in textured hair types.
• Dyeing or chemically treating hair.
• Regularly blow-drying hair.
• Using electric curling irons, straighteners, or curlers; i.e., heat.

Water Damage
Humidity is great for moisture in your skin, but how about for your hair? Hair is porous, which means that it can absorb water from the environment. An increase in humidity increases the water content in hair causing swelling in the hair fibers, and increased volume and frizz.1 The water content in hair is not synonymous with moisturization—it just causes more frizz. However, if you live in a climate that is dry or is usually windy, you will suffer from dry hair. Now that you know what causes dry hair, how can you treat it? Here are several suggestions:

1. Get a physical exam every year. Your primary care physician will probably screen you for vitamin D deficiency and thyroid disease. Always ask to be sure.
2. Keep a healthy diet. Pescetarians have an advantage here because a Scandinavian study showed that a diet rich in marine proteins increased hair elasticity, moisture, and increased the anagen phase (growing phase) of the hair cycle. This is the entire basis for the Viviscal product line.
3. Use a mild, sulfate-free shampoo. Products made specifically to help dry hair will have fewer drying detergents.
4. Use a conditioner. Choose a moisturizing conditioner. It’ll keep hair cuticles lying flat so they hold in natural oils.
5. Avoid gels that contain alcohol. It dries out your hair, so choose hair products without it.
6. Trim split ends. They contribute to that frizzy look and feel. Removing them can make hair feel smoother.
7. Take your vitamins (and minerals). Iron, vitamin D, vitamin A, omega oils, folate, vitamin B12, and selenium  help keep hair healthy. 

References:

1. Aguh, C and Okoye, G. Fundamentals of Ethnic Hair. The Dermatologists’s Perspective. Springer International Publishing 2013.

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Sharleen St. Surin-Lord
Dermatologist
derm@visagederm
www.visagederm.com

Dr. Sharleen St. Surin-Lord is a board-certified dermatologist who has been practicing for more than 13 years. She is in private practice at Visage Dermatology, Largo MD. She also practices at the University of Maryland Capital Regional Health System in Maryland and she is an assistant professor of dermatology at Howard University College of Medicine. Dr. Sharleen is a member of the American Hair Research Society and you can follow her on Twitter, Instagram, and Facebook as DermHairDoc.