There are countless myths about how to prevent hair loss and make your hair grow. 

Many swear by keeping regular hair appointments for a trim, while others steer clear of scissors and simply leave hair to grow by itself. Whatever our own quirks regarding our hair, there are two unreputable things that trigger hair growth: the hair growth cycle, and the way in which dihydrotestosterone (known as “DHT”) can interfere with that cycle.

Understanding the way in which your hair grows, and how DHT impacts it, puts you in a better position to prevent hair loss and achieve fuller, thicker and healthier hair.

Hormones are the most common cause of hair loss for both women and men. In both sexes, the specific hormone responsible for hair loss is the same: DHT, a by-product of testosterone production.

Both men and women need testosterone, as it is responsible for several functions in your body, ranging from regulating your sex drive to keeping your bones and muscle tissue healthy and strong.

In men, the body has a large amount of testosterone and a fairly small amount of estrogenic hormones. In women, this ratio is reversed, with a small amount of testosterone and larger quantities of estrogen and progesterone hormones.

Your body uses testosterone as a precursor for several other hormones, including DHT. DHT affects your hairline by miniaturizing hair follicles, causing the hairs to stop growing normally and leading to them eventually falling out.

This hair loss is called androgenic alopecia, or male and female-pattern hair loss. Overall, it’s the most common form of hair loss. Because androgenic alopecia can miniaturize your hair follicles, the hair that you lose is often gone permanently.

In women, hormonal hair loss produces different results from men. Instead of the horseshoe-like hair pattern or a receding hairline common in men, women with hormonal hair loss usually notice a diffuse thinning pattern across the entire scalp. In simple terms, you probably won’t get a receding hairline if you’re prone to female-pattern hair loss, but your hair might become noticeably thinner.

Luckily, androgenic alopecia is treatable in both men and women.  

THE HAIR STRUCTURE

Let’s begin with hair structure. Hair is made up of 2 parts: the hair follicle and the hair shaft.

The hair follicle anchors the hair into the scalp. It is made up of the papilla and bulb, which are located beneath the scalp. The bulb can be found at the bottom of each strand, and contains the active cells which grow the hair around the papilla. The papilla provides the blood supply to the hair follicle to encourage healthy hair growth.

The hair shaft is the visible hair that grows out from the follicle, and is made up of a hard protein called Keratin and a protective layer called the cuticle. There are around 100,000 hair follicles on the scalp, which is why it is normal to lose up to 100 hairs a day (because there are plenty more where they came from!).

There are 3 stages of hair growth in the cycle, from actively beginning growth from the root to hair shedding. These are known as the Anagen, Catagen, and Telogen phases. 

The Anagen phase

The Anagen phase is the period of growth. The cells in the hair bulb divide rapidly, promoting the growth of new hair. Hair actively grows from the roots for an average of 2-7 years before hair follicles becomes dormant. In this time, hair can grow anywhere between 18-30 inches. The length of this phase is dependent on your maximum hair length, which varies by individual due to genetics, age, health and many more factors.

The Catagen phase

The second phase of your hair growth cycle is the Catagen phase. This period is short, lasting only 2-3 weeks on average. In this transitional phase, hair stops growing and detaches itself from the blood supply. This is called a club hair.

The Telogen phase

Finally, hair enters its third and final stage, called the Telogen phase. This phase begins with a resting period, where club hairs rest in the root while new hair begins to grow beneath it. This phase lasts for around 3 months.

After this, the resting club hairs will fall out to allow the new hair to come through the hair follicle. This is nothing to be alarmed about, and is a natural process that should go completely unnoticed. Each follicle is independent and goes through the growth cycle at different times so you will only shed 50-100 hairs a day, and from all over your head, not in patches. Meanwhile, the rest of your hair will be in the Anagen phase, growing long and strong!

Thinning hair and hair loss can be caused by a variety of internal and external factors. However, the most common cause of male and female pattern baldness is genetics. And while the cause of genetic hair loss has been the subject of debate for many centuries, today, the medical community agrees that it is caused by DHT.

WHAT IS DHT?

DHT is derived from testosterone.  Testosterone is a hormone that’s present in both men and women. In men, DHT contributes to male sex characteristics when you go through puberty. These traits include:

• a deep voice

• increased body hair and muscle mass

• growth of the penis, scrotum, and testicles as sperm production begins

• changes in how fat is stored around your body

As you get older, testosterone and DHT have many other benefits to your body, such as maintaining your overall muscle mass and promoting sexual health and fertility.  

Men typically have more testosterone present in their bodies than women. About 10% of testosterone in all adults is converted to DHT with the help of an enzyme called 5-alpha reductase (5-AR).

Once it’s flowing freely through your bloodstream, DHT can then link to receptors on hair follicles in your scalp, causing them to shrink and become less able to support a healthy head of hair.

And DHT’s potential to cause harm goes beyond your hair. Research has linked DHT, especially abnormally high levels of it, to:

• slow healing of skin after an injury

• enlarged prostate 

• prostate cancer

• coronary heart disease

HAVING TOO LITTLE DHT

High levels of DHT can increase your risk for certain conditions, but having too little DHT can also cause problems in your sexual development as you go through puberty.  

Low DHT may cause delays in the onset of puberty for all sexes. Otherwise, low DHT doesn’t appear to have much effect on women, but in men, low DHT may cause:

• late or incomplete development of sex organs

• changes in body fat distribution, causing conditions such as gynecomastia  

• increased risk of developing prostate tumors  

WHY DHT AFFECTS PEOPLE DIFFERENTLY

Your proclivity to hair loss is genetic, meaning that it’s passed down in your family.

For example, if you’re male and your father experiences male pattern balding, it’s likely that you’ll show a similar balding pattern as you age. If you’re already inclined to male pattern baldness, the follicle-shrinking effect of DHT tends to be more pronounced.

The size and shape of your head may also contribute to how quickly DHT shrinks your follicles.

DHT’S CONNECTION TO HAIR LOSS

If you’ve noticed that your hair starting to thin or recede, it’s easy to stress over what’s causing it to happen. Is it stress? A bad diet? Unlucky genetics? Or is it a lifestyle factor you can fix through a change in behavior?

The reality is that hair loss in men and women is primarily caused by DHT. It binds to receptors in your scalp and -- in genetically susceptible men and women -- is responsible for hair loss.

DHT can seem complicated, but its role in hair loss and thinning is fairly easy to understand once you have a basic knowledge of how your body produces DHT and the effect DHT has on hair follicles.

While DHT is necessary during the early stages of life, it is of no known benefit to adults as we age. Unfortunately, once formed, DHT causes havoc on the hair follicles. It connects to the androgen receptors at the base of the hair follicles, leading to the miniaturization process that causes thinner hair to grow during the anagen phase. These hairs become so weakened that once they fall out, they do not regrow.

In order for men and women to prevent and reverse hair loss, DHT in the hair follicle must be blocked. By blocking DHT, the miniaturization process can be prevented, halted and/or reversed, allowing thicker, fuller and healthier hair to regrow. But while there is one FDA-approved medication that can help reduce the amount of DHT in your body (finasteride, also known as Propecia), it is only approved for men and can have serious side effects.

There are hundreds of topical products that claim to block DHT and help reverse hair loss. However, almost none of them contain ingredients that are clinically proven to help block DHT, which is necessary in order to reverse hair loss. Thus, they are of little to no value. Should you choose to treat hair loss or thinning with a topical product, you need to ensure that it contains ingredients clinically proven to help block DHT.

When we block the effects of DHT on the hair follicle and hair growth cycle, we will start seeing results, such as improved hair growth and hair thickness. The best way to block DHT (if you are unable or unwilling to use finasteride) is to use a topical hair care product with ingredients clinically proven to block DHT.