What can cause hair to gray prematurely?

Dear Graying prematurely,  

White hair is one of the most common and obvious signs of aging. For some people, however, those silvery strands sprout at a younger age. Broadly speaking, premature graying is defined as graying that occurs before the age of 20 in people of Caucasian descent, before 25 in people of Asian descent, and before 30 in people of African descent. Your genes often determine the age you start to gray. That said, mental and emotional stress, exposure to ultraviolet (UV) rays, and many other factors may also cause early graying.  

Why does hair turn gray with age?  

Your hair gets its color from melanin, a pigment made by cells called melanocytes. Hair turns gray when there is a loss of pigment. Gray hair has little pigment, while white hair has none.  This usually happens because the number of melanocytes in the hair follicles has decreased.  

Hair follicles use support systems to break down toxic byproducts that accumulate naturally in the hair. As you age, these systems tend to stop working properly. Over time, hydrogen peroxide and other chemicals naturally build up in the hair follicles, causing an imbalance of free radicals and antioxidants. This is known as oxidative stress, a process which can damage melanocytes and prevent them from making pigment therefore turning your hair gray.   

What can cause premature graying?  

Scientists don’t have all the answers as to why someone may gray early. However, research shows that graying has a genetic basis. If your family has a history of early graying, you might find yourself sporting the salt-and-pepper look earlier in life. Additionally, where your ancestors are from may affect how likely you are to inherit genes that affect when your hair grays. One study found that the onset of gray hair is highly heritable among people of Caucasian descent but less heritable among people from Latin America.  

Beyond genetics, there are other reasons why a person might experience premature graying. These include:  

• Exposure to free radicals: UV rays from the sun, pollution, drinking alcohol, and smoking cigarettes can increase oxidative stress in your body. These damage melanocytes and lead to premature graying. 
• Stress: Your sympathetic nerves are connected to your hair follicles—they're the reason why you get goosebumps when it’s chilly! In times of stress, these nerves release noradrenaline, the hormone responsible for your body’s “fight-or-flight" response. Noradrenaline causes melanocyte stem cells in the hair follicle to rapidly change into actual melanocytes. This results in less production over time, as there are fewer stem cells in the hair follicle to make pigment.  
• Hypothyroidism: Thyroid hormones stimulate the production of melanin in the hair follicle. Low levels of thyroid hormones can lead to gray hair.  
• Nutritional deficiencies: Insufficient levels of protein, Vitamin B12, copper, or iron in your diet can lead to gray hair.  
• Vitiligo: This condition occurs when your body’s immune system attacks melanocytes, causing patches of white skin or hair where melanin has been lost.  

Can gray hair be reversed? 

Emerging research suggests that some gray hairs can naturally revert to their original color after reducing stress. However, this phenomenon is rare and limited to specific hair follicles. Only hair follicles which are at the threshold of turning gray will respond to the presence—or absence—of stressors by changing color.  

If thyroid problems or nutritional deficiencies are the reason for premature graying, hormonal treatment or supplements may be able to reverse the condition. If premature graying is caused by genetic factors, however, it’s unlikely that the gray hairs can return to their original color.  

It’s unclear whether shampoos containing antioxidants such as vitamins C and E or other “anti-aging” compounds like green tea extract can restore hair color. This is because of the brief period of contact these items have with the hair follicles and scalp. 

What are some remedies for gray hair?  

Color depositing shampoos and hair dyes can help to tint gray hair or restore color to it. However, the color may not hold for long because gray hair tends to be coarser and stiffer than hair rich in pigment.  

If premature graying is a cause of concern, you may consider speaking with a health care provider to rule out any underlying health issues. From genetics to lifestyle factors, there are plenty of reasons why your hair might make you look wise beyond your years. But at the end of the day, age is just a number—and every gray hair has a silver lining!