7 Things Your Hair Says About Your Health

Anyone who has watched presidential hair change from campaign to campaign has noticed that stress seems to make hair turn gray. One study suggested that chronic stress may indeed contribute to graying hair by causing DNA damage and reducing the supply of pigment-producing cells in hair follicles. Stress can also cause your hair to fall out.

Another type of stress, known as oxidative stress, may also play a role in gray hair. “Oxidative stress (when cell-damaging free radicals inhibit the body’s repair processes) may affect pigment-producing cells,” says Paradi Mirmirani, MD, a dermatologist with The Permanente Medical Group in Vallejo, California.

Going gray is a natural part of aging, as your hair follicles produce less color as you get older. Your genes also play a role in when your hair turns gray, adds Dr. Mirmirani. Ask your parents how old they were when they saw the first sign of silver, and you might follow suit. In fact, one study identified the gene responsible for gray hair.

Brittle hair is one symptom of Cushing’s syndrome, a rare condition caused by too much cortisol, the body’s primary stress hormone. But there are many other more obvious symptoms of Cushing’s syndrome, including high blood pressure, fatigue, and back pain, says Mirmirani.

Treatment for Cushing’s syndrome may include changing the dose of medication that could be causing the condition, such as glucocorticoids, which are steroids used to treat inflammation caused by a variety of illnesses. Other people might need surgery, chemotherapy (if a malignant tumor is the cause of Cushing’s), or radiation therapy to correct the adrenal gland’s overproduction of cortisol.

People who have hypothyroidism, a condition that occurs when your thyroid gland doesn’t produce enough thyroid hormones, might notice increased hair shedding and a change in hair appearance, says Mirmirani.

About 4.6 percent of the U.S. population ages 12 and older has hypothyroidism, according to the National Institute of Diabetes and Digestive and Kidney Diseases, although most cases are mild. It can cause thinning hair and other symptoms, such as tiredness, cold intolerance, joint pain, muscle pain, a puffy face, and weight gain. A thyroid-stimulating hormone (TSH) test will diagnose the condition, and treatment involves taking thyroid medication.

In addition to thinning hair, certain thyroid disorders put you at risk for an autoimmune hair-loss condition called alopecia areata. This type of hair loss causes round patches of sudden hair loss. It happens when the immune system attacks hair follicles.

If you’re suddenly noticing a lot more hair in your hairbrush or on your shower floor, this could be a sign that your body has low iron stores, or anemia, and may warrant testing. ”This is another blood test we do when you complain of hair changes,” says Mirmirani. She says she is particularly likely to order this blood test for people who are vegetarian or for women who have heavy periods, both of which increase the chance that hair changes are due to low iron.

It’s not completely known why low iron can cause hair loss, but iron is critical for many biological and chemical reactions, perhaps including hair growth, says Rebecca Baxt, MD, a dermatologist in Paramus, New Jersey. If your doctor determines that you are truly iron deficient, eating more foods that are high in iron, or taking an iron supplement, might help with hair loss, she adds.

Hair shedding can also happen (temporarily) with sudden changes in estrogen levels and is often noticed after pregnancy or stopping birth control pills.

Protein is essential for hair health and growth (a lack of protein has been linked to hair thinning and loss). Protein deficiency isn’t a problem for most Americans, says Mirmirani — most adults need 0.8 grams of protein per kilogram of body weight. Good sources of protein include nonfat Greek yogurt, tilapia, chickpeas, and chicken breast.

People who have gastrointestinal difficulties or who just had gastric bypass surgery may have problems digesting protein. These specialized situations will have to be managed with your doctor's help. But most hair thinning, even in women, is likely due to genetics.

Yellow or white flakes in your hair, on your shoulders, and even in your eyebrows are a sign of dandruff, a chronic scalp condition. Dandruff doesn’t usually indicate a serious health problem, and it can usually be treated with over-the-counter specialty hair shampoos or a prescription shampoo.

One of the most common causes of dandruff is a condition called seborrheic dermatitis, according to the Mayo Clinic. Those with seborrheic dermatitis have red, greasy skin covered with flaky white or yellow scales. A yeast-like fungus called malassezia can also irritate the scalp. Not shampooing enough, sensitivity to hair care products, and dry skin can also cause dandruff. (Dandruff is usually worse in winter, when indoor heating can make skin drier.)

Although hair can tattle on your health conditions, Mirmirani says that patients more commonly complain about the damage done by coloring and using heat to style hair.

Too much heat, from daily flat iron use or blowouts, can certainly damage your hair, making it dry, brittle, and hard to maintain, says Tania Moran, a licensed hairstylist at Swank Hair Salon in New York City. Moran recommends using no more than one hot tool per day (infrequent double heat processes are okay, but not daily).

Whenever you’re applying heat to your hair, always use products with protective ingredients, she adds. “Serums and shine drops tend to have qualities that preserve the hair when using direct and indirect heat,” she explains.

Getting your hair professionally colored is unlikely to cause much damage, Moran says, but bleaching your hair and using boxed hair color at home can have adverse effects. You can mitigate any damage to your hair by using the right products. “Post-color treatment, use proper color-preserving and moisturizing shampoo,” Moran recommends.

Highly treated hair may mask certain problems and make it difficult to see or feel what your hair can tell you about your health.