What Is the Hormone Responsible for Hair Growth?

Hair growth is completely natural. All mammals who have hair experience a hair growth cycle, but humans are the only mammals whose hair shedding is random and not seasonal.

When it comes to the randomness of human hair growth and hair shedding, one reliable factor always plays a part: our hormones. Did you know that hormones affect our moods and can also be responsible for hair growth and loss?

So, how exactly do hormones affect the hair? Read on to find out what hormones are responsible for hair growth and hair loss, as well as the best products to encourage thicker, fuller looking hair.

Understanding the Hair Growth Cycle

To understand the process through which we grow and lose our hair, it's important to understand the hair growth cycle.

The hair growth cycle is a dynamic process that has three phases. The duration of each phase has a direct effect on how long and full-looking the hair is. The first phase is called the anagen phase and this is where active mitotic division occurs in the basal matrix of the hair follicle. This promotes the growth of hair and this stage is usually the longest in areas like the scalp where hair is continuously growing — sometimes two to six years.

Once the hair grows out, the follicle enters a transitional phase called the catagen stage where no hair growth occurs and the hair root begins to shrink away from the scalp or skin. The third phase of the growth cycle is called the telogen phase, which is a resting phase. This phase can last up to 100 days and during this phase, the human head sheds anywhere from 25-100 hairs a day. Then, the cycle repeats itself.

Different hair follicles are in different stages at any given moment, although the largest percentage of hair is in the anagen phase. The hair growth cycle usually stays consistent during our lifetimes but sometimes factors like genetics and hormones can play a role in disrupting it.

Read: How Long Does It Take to Grow Hair 12 Inches?

How Hormones Influence Hair Growth

While the shedding of hair in humans is random, hair growth and loss can be influenced by hormones.

Hormones like DHEA (a hormone produced by the adrenal glands) and testosterone play the largest role in hair growth in general. When levels of these hormones are too high, people can experience excessive hair growth, particularly on the body and face. When hormone levels drop, however, the reverse can occur. This leads to thinning hair and in some cases, hair loss. As women age, androgens actually increase female hair loss.

One hormone in particular called dihydrotestosterone (DHT) carries most of the blame when it comes to hair loss. DHT is a male sex hormone and derivative of testosterone that is found in both men and women. How DHT affects hair loss isn't entirely understood, but the thesis is that some people have higher levels of DHT in the body and some are more sensitive to it.

"While androgens are present in both men and women, they're typically at much higher levels in men. This is why hair loss is more common in men than women," said Dr. Alpana Mohta. "That doesn't mean that women are immune to androgen-related hair loss. In fact, hormonal imbalances are one of the most common causes of hair loss in women."

DHT attaches to the androgen receptors on the hair follicle and shrinks them, making the anagen phase of the hair growth cycle shrink and the telogen (resting phase) increase. This leads to male pattern hair loss, usually most visible in a receding hairline. This problem isn't exclusive to men, even though male pattern baldness is much more commonplace in conversations about hair loss.

"There are a few different ways that hormones can contribute to hair loss in women," said Dr. Mohta. "One is by directly affecting the hair follicles. The hair follicles are sensitive to androgens, and when they're exposed to high levels of androgens, they can shrink. This is called follicular miniaturization, and it's a major contributing factor to hair loss."

The hormones produced by the thyroid gland also play a part in hair thinning. If someone experiences a thyroid disease like hypothyroidism (a condition in which the thyroid isn't active enough) their metabolism slows down. To compensate for that, the body begins to shut down less vital functions like hair growth.

Even pregnancy can affect the hair. Many women experience the sensation of having thicker hair during pregnancy. This is because during pregnancy the hair follicles spend more time in the anagen phase. Once the pregnancy is over and estrogen levels return to normal, women can experience hair thinning as the hair returns to its normal growth cycle.

Other women could experience hair loss due to telogen effluvium, which can occur as a woman's hormones swing back to pre-pregnancy levels, or simply when stress is present.

"Telogen effluvium is often caused by stress, but it can also be caused by hormonal fluctuations," Dr. Mohta explained. "The most commonly implicated hormones are cortisol and thyroid hormones. An imbalance in the levels of estrogen and progesterone during pregnancy can also cause post-partum telogen effluvium."

Read: Everything You Need To Know About PCOS Hair Loss

Hormone Imbalances

Another way hormones can affect hair growth and hair thinning is when hormone imbalances occur. Some hormone imbalances occur due to a medical condition, while others have to do with lifestyle.

"Hormone imbalances affect hair growth and hair thinning in a variety of ways," said Dr. Liz Jane, a medical doctor and writer specializing in internal medicine, gynecology and nutrition. "Polycystic ovarian syndrome and menopause both involve hormone imbalance, and are associated with hair thinning," she adds. "Additionally, androgenic alopecia is a common hormonal hair loss condition that results in thinning all over the scalp."

Menopausal women and women with polycystic ovary syndrome (PCOS) might notice changes in their hair. These hair changes are usually due to imbalances in estrogen and progesterone levels. The largest dip in estrogen occurs in peri-menopausal women and menopausal women, which is why some women notice hair loss as they move into their menopausal years.

"Hormone imbalances can result in hair loss on the scalp, as well as on the face and body," said Dr. Jane. "They can also result in the formation of fine, weak hairs called vellus hairs."

There are a variety of lifestyle factors that can contribute to hormonal imbalance like poor diet, vitamin deficiencies and stress. "A poor diet can take a toll on the whole body, including the hair follicles," explains Friese. In some cases practicing intermittent fasting might also affect your hormones.

When it comes to diet, processed foods, soy and dairy products, caffeine and even red meat can affect your hormones. If you want to rebalance your hormones, try eating healthy foods like:

• Cruciferous vegetables (like brussels sprouts, broccoli, kale and cauliflower)
• Healthy fats (found in olive oil, avocado oil, raw nuts, seeds, nut butters and avocado)
• Quality protein 
• Flaxseeds
• Whole fruit (in moderation)
• Whole grains
• Herbs and spices (like ginger, turmeric, paprika and garlic)
• Magnesium-rich foods (foods like avocado, nuts, seeds, quinoa and dark leafy greens)

To reduce stress, practices like yoga, meditation, journaling and other mindfulness techniques can help. Be sure to talk with your healthcare provider before beginning any kind of fasting practice or extreme dieting as this can also affect your hormones.

Treatments for Hormone-Related Hair Thinning

If hormonal imbalances such as menopause trigger hair loss, doctors might recommend hormone replacement therapy to help. Possible treatments for hormonal hair loss in women include birth control pills to introduce more estrogen or progesterone into their system. Other options include anti-androgen medications, as androgens can speed up hair loss in some women, especially those with PCOS.

Men who are genetically predisposed to male pattern baldness are thought to be more sensitive to DHT, while others tolerate it better and don't experience male pattern hair loss. Men who experience male pattern hair loss are often prescribed DHT blockers like finasteride as a hair loss treatment that works to block the DHT hormones from disrupting the hair growth cycle.

In some cases, hair loss is treated with a treatment called platelet-rich plasma (PRP). In this case, a person's blood is extracted and the platelets are separated and converted into a protein-rich plasma, which is beneficial for tissue healing. This plasma is then injected into the upper layer of the scalp to promote hair regrowth.

Consider a Natural Approach to Hair Wellness

If you're looking to encourage thicker looking hair, there are natural options you can use to nourish your body and promote healthy, thicker, fuller looking hair. VEGAMOUR's GRO Hair Serum and GRO Biotin Gummies can be used in tandem to boost hair health naturally. This powerful combo nourishes your strands inside and out with a delicious daily gummy that is fortified with biotin, folic acid, zinc, vitamins B5, B6 and B12, as well as vitamins A, C and E to help neutralize follicle-damaging free radicals.

The Takeaway

Whether hair loss is caused by stress, the natural aging process or hormonal disorders, understanding the science behind hair, the hair growth cycle and the reasons for hair loss can arm you with the knowledge you need to decide how to best take care of your hair and body. Maintaining a healthy, balanced diet and practicing mindfulness techniques are important for overall wellness but also for your hair wellness. If you experience changes in your hair as a result of hormonal changes, it may be a sign that it's time to talk with your healthcare provider and make some healthy lifestyle changes to improve the balance of your hormones for the sake of your overall health and well-being.

More From VEGAMOUR

• Shop: The Best Hair Products for Thicker Looking Hair
• How Does Cortisol Affect Hair Loss and Growth?
• 5 Things You Should Avoid If You Have Thinning Hair
• What Your Hair Can Tell You About Your Overall Health

Photo credit: Tachina Lee/UnSplash