Can progesterone help reduce or get rid of Fibroids? 

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Fibroids (uterine leiomyoma, myomas, fibromyoma) are benign, usually painless tumours found in the uterus, and are made of smooth muscle and connective tissue. They are characterised by overproduction of extracellular matrix. Although the aetiology is unknown, there's strong evidence they are caused by oxidative stress. Starting as microscopic bodies, they can grow to the size of a grapefruit or larger, sometimes filling the entire uterus.

There are five main types...

  • submucosal
  • subserosal
  • intramural
  • pedunculated
  • cervical

From 15 to 20% of reproductive women develop fibroids. In the United States it's estimated that up to 70% of white women develop fibroids at some point by age 50; among African-American women, that number is closer to 80%. But they occur most frequently in women from the mid thirties on, affecting 30 to 40%. It's from about the age of thirty five that anovulatory cycles begin.

During these cycles when ovulation does not occur, progesterone levels drop sharply. This in effect allows oestrogen to rise. Oestrogen is a mitogenic, excitatory, inflammatory hormone and fibroids are directly related the the oestrogen environment. i.e. increased oestrogen leads to increased growth. HRT also statistically increases uterine fibroid volume.

Oestrogen's implication in fibroids is well known, so much so that women nearing Menopause are often advised to do nothing until menopause begins. With the drop in oestrogen levels the fibroids are absorbed back into the uterus.

As a study puts it...

"Progesterone is known to be not only a progestational compound but also to exert various anti-oestrogenic actions: it prevents oestrogen-induced abdominal fibroids, oestrogen-induced growth of the myometrium, and oestrogen-induced excessive luteinization."

Very heavy bleeding, clots, very long periods, with a short break in between are the hallmark of fibroids. They often cause irregular, sometimes painful periods, and pressure (due to their size and number).

Bleeding is generally the most common feature.

In less than 1% of cases, cancer can arise, usually forming leiomyosarcomas. The malignancy is more common in older, post menopausal women, who are found with rapidly growing tumours, bleeding, and some pelvic pain or discomfort.

Matrix metalloproteinases (MMPs) are proteolytic enzymes involved in tissue remodelling. They degrade collagen IV and stimulate chemokines and cytokines. Although limited activity of MMPs are essential, excessive activity is harmful to the healing process.

Excessive activity is involved in a wide variety of pathological processes, leading to several Inflammatory diseases. Including the spread of metastatic cancer cells, osteoarthritis, rheumatoid arthritis, atherosclerosis, pulmonary fibrosis, emphysema, neuroinflammation, tuberculosis, skin diseases, lupus, continual, heavy bleeding, endometriosis and fibroids.

Progesterone is a known inhibitor of MMPs, whereas oestrogen stimulates their secretion. Studies ranging from stroke, various cancers, brain inflammation following trauma, endometriosis, arthritis and more, where MMPs are involved, have found progesterone to inhibit their production.

This from one paper...

"These results suggest that activation of PR-B (progesterone receptor-B) by progesterone results in tumor suppression by inhibiting cell growth and invasiveness via suppression of the expression of MMPs."

MMPs are an essential part of Menstruation. When progesterone withdrawal occurs at the end of the monthly cycle, the level of MMPs rise. Their role is to break down the uterine lining and then bleeding commences.

But a high level of MMPs, plus a high level of oestrogen, which stimulates them further, will ensure continual bleeding. With oestrogen building the lining, and the MMPs breaking it down this vicious cycle needs to be broken. Progesterone does this safely and effectively.

Vitamin D as the hormone, 1,25(OH)(2) vitamin D3, suppresses the production of MMPs. But many studies have found low vitamin D levels are statistically associated with the occurrence of fibroids. Not only that, but the lower the level, the larger the fibroid. Sufficient vitamin D is associated with a reduced risk of uterine fibroids.

They are three to four times more common in African American women, who also have a ten times higher incidence of low vitamin D than white women. And yet few if any women are advised to take vitamin D and get their levels up high. In spite of studies finding vitamin D reduces the volume of fibroids.

In fact one 2011 study concludes with...

"Thus, hypovitaminosis D appears to be a risk factor for uterine fibroids."

N-acetyl cysteine (NAC) was shown to completely suppress MMP-2 and MMP-9 activity in one study on fibroids. A potent antioxidant, it's also effective for heavy bleeding, suppressing the same MMPs which break down the lining.

Low taurine levels are found in any dysfunctional uterine problem. i.e. irregular bleeding, endometrial cancer, cystic endometrial hyperplasia and fibroids.

Cranberry proanthocyanidins has been found to inhibit the production and activity of MMPs in a concentration-dependent manner.

As many studies have found, fibroids generally decrease during Pregnancy due to the high level of progesterone. But conversely they are also found to enlarge rapidly. This has been found to be due to the influence on cellular proliferation by hCG (human chorionic gonadotrophin).

hCG is produced in response to pregnancy, one of it's roles is to stimulate the corpus luteum to continue secreting progesterone. But in excess it also causes cells to proliferate. In the event of low progesterone production by the corpus luteum, this will not prevent fibroids from enlarging during pregnancy.

The following risk factors for Fibroids have been found...

  • high levels of oestrogen
  • oxidative stress
  • hypertension
  • diabetes
  • pelvic inflammatory disease
  • chlamydial infection
  • IUD when it causes infectious complications
  • perineal talcum powder use
  • low serum adiponectin levels
  • high levels of IGF-1
  • tamoxifen
  • genistein
  • organochlorine pesticide exposure

Adiponectin is an adipocyte-secreted hormone, low levels are found in fibroids, Insulin Resistance and diabetes. There is also an inverse relation between adiponectin levels and body mass index.

Insulin-like growth factor-1 (IGF-1) promotes tissue growth, and plays a role in fibroids through stimulating proliferation and inhibiting apoptosis. Progesterone treatment significantly decreases IGF-1 in fibroids.

Moreover, IGF-1 enhances aromatase activity. Aromatase is a key enzyme in the biosynthesis of oestrogen. High levels of IGF-I lead to increased levels of oestrogen, which in turn stimulates further growth of the fibroids. Progesterone is an aromatase inhibitor.

High levels of IGF-1 are found in cows treated with bovine somatotropin (bST) or growth hormone. The majority of the milk produced in the States is from cows treated with bST, women drinking this milk are at increased risk of developing fibroids.

Tamoxifen, a weak oestrogen given to women to prevent recurrence of breast cancer, increases the risk of not only endometrial cancer, but also for uterine leiomyosarcoma. Furthermore it was found that tamoxifen causes the development of new fibroids and ovarian cysts.

Genistein, an isoflavone found primarily in legumes, with soy having the highest content, has weak oestrogenic activity. It's been found to stimulate the growth of fibroids by increasing IGF-1 and oestrogen receptor activity. Women eating soy or other legumes are at increased risk of fibroids.

Endocrine Disruptors, in particular the organochlorine pesticides, many of which mimic oestrogen, have been found to stimulate the proliferation of fibroid cells.

Natural treatment for Fibroids

The amount of progesterone needed will be dependent on the individual and the severity of the problem. Use between 100-200mg/day of progesterone. In severe cases start on no less than 200mg/day, vary the amount used following symptoms as a guide. If heavy, continual bleeding is a feature, 400mg/day is needed.

Consider taking at least 2000mg/day NAC, 2000mg/day taurine and at least 5000iu vitamin D (dependant on levels). And if heavy bleeding is an issue add 1000mg/day bioflavonoids.

Many women are under the mistaken impression that as they make only 5-20mg/day progesterone, some say up to 40mg/day, that that should be sufficient when supplementing. It is if there are no problems at all.

But once oestrogen rises, for whatever reason, far more progesterone is needed to overcome it. Some of the reasons for its rise are given above.

For more information see How to use progesterone cream

Before using progesterone it's essential to read the page on Oestrogen Dominance.

A vitamin D test is essential, see the following websites for more information on testing...

Conventional treatment for Fibroids

Current medical treatment is a hysterectomy, uterine artery embolisation (UAE) or laparoscopic myomectomy (LM) to remove them. Or anti-inflammatory drugs for the pain, and oral contraceptives to control the heavy bleeding. Fibroids are the leading cause for hysterectomy in the United States.

Website references

Mayo Clinic




Patient UK

Reference papers

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Uterine Fibroids Cost the U.S. Billions, Study Finds

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Aberrant Serum Adiponectin Levels in Women with Uterine Leiomyomas

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Why is Parity Protective for Uterine Fibroids?

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Paracrine Mediators of Endometrial Matrix Metalloproteinase Expression

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Increased milk levels of insulin-like growth factor 1 (IGF-1) for the identification of bovine somatotropin (bST) treated cows

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Expression of gelatinase B by trophoblast cells: down- regulation by progesterone

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Progesterone inhibits glucocorticoid-dependent aromatase induction in human adipose fibroblasts

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