Can Low Progesterone Cause Hair Loss? | A Meta-Analysis of the Data

Hormonal imbalances are issues that plague many women around the world. From abnormal hair growth to irregular periods and hair loss, wacky hormones can be seriously frustrating.

One question you might be asking is: can low progesterone cause hair loss?

In this article, you’ll learn:

• The science behind progesterone;
• How to know if you have low progesterone;
• The research behind progesterone and hair loss;
• The biological mechanisms that connect progesterone and hair loss;
• How to boost progesterone naturally; and
• If low progesterone truly can cause hair loss.

Just keep reading!

What Is Progesterone?

Progesterone is a steroid sex hormone that is produced mainly by the ovaries (1). Its main role is in the menstrual cycle, where it stimulates a growing ovarian follicle to release its egg mid-cycle. When this happens, other cells begin to form the corpus luteum which is responsible for progesterone production in the second half of the menstrual cycle.

It’s also responsible for the cellular division within the uterine walls, which creates a “home” for an egg to implant if it’s fertilized.

Progesterone functions in the body by binding to progesterone receptors. There are two receptors: PR-A and PR-B.

When progesterone binds to each receptor, they signal different effects. These receptors are expressed in various tissues of the human body, namely the uterus, ovary, brain, and breast.

Progesterone is a complex hormone because its effects are largely contextual, meaning the way it acts is dependent on circumstances outside of progesterone’s “standard” functions.

For example, in the first half of the menstrual cycle, estrogen promotes the growth of the uterine walls while progesterone inhibits it, preventing overgrowth. However, progesterone stimulates cell proliferation in the uterine wall at the end of the cycle.

Additionally, progesterone can also increase the levels cAMP, a messenger in the body that stimulates rapid cell division.

But, that’s not the end of it.

Further complicating our understanding is progesterone’s intricate relationship with estrogen.

Progesterone and estrogen work together and oppose each other to produce their effects in the body. In most cases of hormonal imbalance, the causes are not likely related to the level of one hormone on its own.

What Are the Symptoms of Low Progesterone?

One of progesterone’s functions is stimulating GABA signaling in the brain, the calming neurotransmitter. As a result, women with low progesterone may experience anxiety. This can be in addition to fertility issues and irregular menstrual cycles (1, 2, 3, 4).

Low Progesterone and Hair loss

There isn’t a robust body of research on progesterone levels and their connection to hair loss. Right now, most scientific research supports the association between excess androgens and hormone-related hair loss. Because of this, there isn’t a lot of interest in investigating whether or not progesterone levels might influence hair loss.

But, it’s worth noting that high androgen levels aren’t always the cause of female pattern hair loss (5). This tells us that there is more research needed on the exact cause of female pattern hair loss, including the effects of progesterone.

With the small body of research that we have, let’s talk about how low progesterone might cause hair loss.

Studies On Progesterone in Hair Loss

The main research available on progesterone and hair loss has been using a synthetic progesterone called cyproterone acetate that has anti-androgen properties (6). It should be noted that this treatment is not available in the United States.

One Year Study of Cyproterone Acetate on Women Ages 12 to 79

In one women-only study, cyproterone acetate had similar results to spironolactone, another anti-androgen. Over a 12-month period, 44 percent of women experienced hair regrowth, 44 percent saw no changes, and 12 percent had worsening of hair loss.

While this shows promise that progesterone might impact hair loss and growth, the study of only 80 women between ages 12 and 79 is too small to make generalizations about how progesterone might impact all female pattern hair loss sufferers (7).

Three Month Study of Cyproterone Acetate on Women Ages 18–40

In another cyproterone acetate study consisting of women ages 18–40, 83 percent of women’s hair stopped falling out while 77 percent experienced hair regrowth.

However, this study observed the administration of ethinyl estradiol, a synthetic estrogen, with cyproterone acetate (8). So, it isn’t a good representation of how progesterone alone affects hair loss.

Hormone Samples of 125 Women With Androgenic Alopecia

Of most relevance is one German study that examined hormone levels of female androgenic alopecia sufferers. Only 11 percent of participants had abnormal progesterone levels (9).

A Hair Loss Therapy Review

Most recently, a 2018 review on all therapies for female pattern hair loss suggests that anti-androgen therapies are effective for female pattern hair loss. However, this review still states that this cyproterone acetate doesn’t produce as significant results compared to minoxidil (10).

What Does All This Mean?

The issue with studies on cyproterone acetate is that they study the effects of synthetic progesterone. Our body’s natural progesterone is so complex that it can’t possibly mimic it, which may not best represent what natural progesterone can do.

In terms of low progesterone and hair loss, it’s hard to estimate whether or not low progesterone levels are truly associated with hair loss based on one study of 125 women’s hormone samples.

How Low Progesterone Might Impact Hair Loss

There’s such a small amount of concrete data that connects hair loss to low progesterone levels. But, there are some plausible ways that progesterone might influence hair loss and growth.

Progesterone Is an Anti-Inflammatory

Progesterone has been shown to reduce inflammation in brain cells and the digestive system. Researchers have also observed progesterone’s ability to lower blood and tissue levels of inflammatory proteins like IL-6 and TNF-α and markers of oxidative stress which is mediated by free radicals.

This might mean that progesterone can reduce inflammatory protein production directly and upregulate the body’s natural antioxidant systems (11).

So, what does this mean for hair loss?

Inflammation and scalp tension are some of the primary underlying factors in the development of androgenetic alopecia. These factors alone and the free radicals they produce can signal downstream events like increased androgens on the scalp, blood vessel calcification, fibrosis development around hair follicles, and thickening of the skin around the hair follicle.

As a result, the hair follicle is miniaturized, growth space is restricted, and blood flow is impeded. The result is a miniaturized hair or even complete loss of growth due to poor nutrient delivery (12).

Free radicals themselves can also damage the stem cells in the hair matrix, preventing them from producing hair (13).

If progesterone truly does lower inflammation and boost natural antioxidant defense systems, progesterone may be able to prevent hair loss by resolving some of the underlying factors that can cause it.

Progesterone Stimulates cAMP

Dermal papilla cells are key in the production of the hair shaft, so much so that researchers believe harnessing their potential to stimulate the differentiation of cells around it might be a treatment for alopecia (16).

So, how can we do that?

Cyclic adenosine monophosphate, or cAMP, is a compound that is involved in cell signals. One of its functions is regulating cell division and proliferation. In dermal papilla cells, an increase in cAMP concentration was shown to enhance upregulation FGF-7 expression, which is key for hair growth (14, 15, 17).

Although the chemical adenosine is most classically used to increase cAMP, progesterone has also been shown to boost cAMP levels in brain cells. This is promising, however, whether this action of progesterone translates to the hair follicle hasn’t been explored (1).

In one study, androgenetic alopecia scalps have shown markers of progesterone receptors. However, more studies are needed to see how many progesterone receptors are present as well as how this might impact cAMP signaling within the hair follicle (18).

By stimulating cAMP, progesterone may be able to promote healthy hair.

Hair Diameter Increases During Pregnancy

Pregnancy is a time characterized by high estrogen and progesterone levels. Progesterone is required for implantation, maintenance of pregnancy, and preventing the mother’s immune system from attacking the baby (19).

Besides many women’s reports, research has demonstrated that hair actually increases in diameter during pregnancy (20).

While this isn’t necessarily indicative of progesterone and hair loss alone, it does suggest that progesterone plays a role in hair growth. This means that healthy progesterone levels have the potential to boost hair fullness.

Progesterone Receptor A and Androgens

The majority of the scientific literature points to androgens as a critical factor in androgenetic alopecia. This is the basis of many anti-androgenic drugs designed to treat hormonal hair loss. However, activation of one progesterone receptor, Progesterone Receptor A (PR-A), has also been shown to diminish androgen activity (1, 12).

Progesterone and estrogen both increase the expression of PR-A in the body at high concentrations (21). In this way, progesterone (by increasing the concentration of PR-A receptors) may theoretically help decrease the activity of androgens in hair follicles and surrounding tissues.

However, whether this increased expression can occur independently of normal estrogen levels warrants more research. Additionally, estrogen may compensate for PR-A expression in the presence of low progesterone.

Progesterone and Iron

A balance between estrogen and progesterone is essential for a regular and normal menstrual cycle.

Estrogen is important for thickening the uterine lining in the first phase of the menstrual cycle. Progesterone antagonizes this, as mentioned earlier, and prevents the uterine lining from overgrowing. If progesterone levels drop in relation to estrogen, something called endometrium hyperplasia, or excessive growth of the uterine lining, occurs. This can lead to excessive bleeding at the end of the menstrual cycle (1, 22).

Iron is easily conserved in the body unless there is excessive blood loss, like in the case of heavy menstrual bleeding (23). Thus, low progesterone levels may lead to excessive iron loss following abnormally heavy periods.

When matched for age and sex, premenopausal women who suffer from female pattern hair loss have much lower iron stores compared to those who don’t experience hair loss. Although we don’t know exactly how iron might influence hair loss, we do know that in a low oxygen environment, more testosterone is converted to DHT than estrogen by the enzyme aromatase.

Iron is essential for providing oxygen to the blood. Additionally, the aromatase enzyme that converts is from a class of enzymes known as the cytochrome P-450 enzymes. These are monooxygenase enzymes that are dependent on iron for their function (24, 26, 27).

Moreover, progesterone is recognized as a regulator of hepcidin and may increase its production (25). This is a peptide hormone that regulates the release of iron from storage cells into the blood to be used by the rest of the body. In this way, progesterone helps mediate iron availability in the body. So, decreased progesterone may result in decreased hepcidin production and lower blood iron levels.

Considering low blood iron levels and hair loss are related, this may be a mechanism by which low progesterone levels might cause hair loss. It also means that healthy progesterone levels may help you achieve healthy hair by regulating iron levels.

How to Boost Progesterone Naturally

Certain nutrients from food act as precursors and cofactors for progesterone production. The good news is that by eating these foods, you may be able to boost progesterone levels!

Polyunsaturated Fatty Acids

In vitro studies have shown that arachidonic acid, a type of omega-6 fatty acids in the body, plays an important role in the production of sex hormones like progesterone. Although it’s important to maintain a healthy balance between omega-6 and omega-3 fatty acids to prevent excessive inflammation, the critical function of this fatty acid shouldn’t be ignored (28, 29).

Some healthy sources of omega-6s include:

• Pumpkin seeds
• Flax seeds
• Sunflower seeds
• Almonds
• Walnuts
• Brazil Nuts

You should always eat these foods with a diet high in fatty fish and seafood to keep inflammation low.

Cholesterol

Cholesterol is the precursor to all the sex hormones of the body.

An enzyme called CYP11A1 converts cholesterol to pregnenolone in the mitochondria of cells. Pregnenolone is the converts into progesterone or testosterone, which is aromatized into estrogen (30).

Eggs and meats are just two foods with high cholesterol levels.

Some sources of cholesterol in the diet are:

• Eggs
• Red meat
• Dairy

By including a healthy amount of these foods in your diet, you can provide your body with the precursors to progesterone.

Cofactors for CYP11A1

With the consideration that CYP11A1 produces pregnenolone needed for progesterone production, it’s important that this enzyme functions properly.

This means it needs to have all of the cofactors it needs to produce. One of these is NADPH which requires niacin (vitamin B3). By eating a diet high in niacin, you can ensure adequate levels of NADPH needed for progesterone production (31, 32).

Food sources of niacin are (33):

• Turkey breast
• Salmon
• Tuna
• Pork
• Beef products
• Peanuts
• Rice
• Potato

Niacin is a water-soluble vitamin and isn’t stored by the body. So, it’s important to consistently replenish your levels with food.

Does Low Progesterone Really Cause Hair Loss?

So, does low progesterone really cause hair loss? Honestly, it’s hard to say.

There are almost no studies that examine a real link to progesterone levels and hair loss. Although there have been studies on synthetic progesterone supplementation that have been successful for women, it’s not a great representation of how our body’s natural progesterone levels might work.

There’s also not a whole lot we know about progesterone’s role in hair growth either, compared to what we know about estrogen and testosterone. But, some of progesterone’s known functions may help hair loss sufferers, in theory.

Overall, more research is definitely warranted on a possible link between low progesterone and hair loss.

If you believe that your low progesterone levels and hair loss are related, you can boost levels naturally using food. Cholesterol, polyunsaturated fatty acids, and niacin are just a few nutrients that are involved in the production of progesterone.

If you ever have any questions or just want to say hey, don’t hesitate to leave a comment here or on any of my other posts!