Can vitamin D shrink large fibroids?

Uterine fibroids are noncancerous growths that develop in or on the muscular walls of the uterus. Also known as leiomyomas or myomas, fibroids range in size from seedlings, undetectable by the human eye, to bulky masses that can distort and enlarge the uterus. Fibroids can also grow as a single tumor or cluster.

While fibroids are typically benign (noncancerous), they can occasionally cause problematic symptoms, like heavy menstrual bleeding, pelvic pain and pressure, and problems with pregnancy and infertility. Some women with fibroids may be unaware of them because they do not have any symptoms. But for some women, fibroids may be incredibly bothersome and disrupt daily life.

Fibroids are a very common problem, affecting an estimated 80 percent of women by age 50. However, the highest prevalence is among women in their 40s and early 50s. Risk factors for fibroids include being overweight, African American ethnicity, early onset of menstruation, vitamin D deficiency, and a family history of uterine fibroids.

For most women, fibroids do not require treatment unless they are causing symptoms. But when treatment is necessary, there are several options available, including medication and surgery. One potential natural treatment that has been a topic of interest in research is vitamin D. Some studies suggest this important vitamin may help slow or prevent the growth of uterine fibroids.

What is vitamin D?

Vitamin D is a unique vitamin that functions as a prohormone. This means when it enters the body, it must first undergo modifications to become fully active.

There are two major forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is obtained mostly from fungi and some plants when they are exposed to UV light. You can get vitamin D2 from foods like mushrooms. Meanwhile, vitamin D3 can be synthesized in the skin through sun exposure or consumed in animal-based foods like fatty fish, fish liver oils, and egg yolks.

No matter whether vitamin D originates in the body, from exposure to sunlight, or through the diet, it must go through two hydroxylation steps in the body for activation. The kidneys and liver transform vitamin D into the hormonally active form known as calcitriol. Calcitriol is crucial for calcium absorption and maintaining adequate calcium and phosphate levels for bone mineralization and bone health.

According to the National Institutes of Health (NIH), the recommended daily allowance of vitamin D is:

– 600 IU daily from ages 1 to 70 years
– 800 IU daily for adults over 70 years

However, many experts argue that these recommendations are too low. Some recommend getting at least 1000 to 2000 IU daily, especially for those with insufficient blood levels. Blood levels of vitamin D less than 30 ng/mL are considered deficient.

What causes fibroids?

The exact cause of uterine fibroids is still unknown. However, fibroids appear to be tied to hormone imbalances and genetics.

– Estrogen – Fibroids contain a high number of estrogen receptors. They appear to respond strongly to the female hormone estrogen. Estrogen dominance is believed to stimulate fibroid growth.

– Progesterone – This hormone increases during the menstrual cycle to thicken the uterine lining in preparation for pregnancy. Low levels of progesterone relative to estrogen are thought encourage the formation of fibroids.

– Genetics – Research indicates that inherited genetic changes or mutations may predispose women to developing fibroids. Having a mother, sister, or daughter with uterine fibroids increases your risk. Fibroids are more common in African American women.

– Extracellular matrix (ECM) – Fibroids have excessive amounts of extracellular matrix, which is the collection of proteins and carbohydrates surrounding cells. The high ECM content causes fibroids to be rigid and stiff.

Abnormalities involving these hormones, genetics, and ECM composition allow the smooth muscle cells that make up the uterus to reproduce excessively and form tumors. Fibroids typically grow slowly over several years. Growth factors secreted by fibroid cells also increase the production of extracellular matrix.

Large fibroids can outgrow their blood supply, causing them to degenerate. The resulting cell death can lead fibroids to calcify and form hard, solid areas.

Fibroid symptoms

Most women with uterine fibroids will not have any related symptoms or complications. However, depending on their location, number, and size, some women may notice:

– Heavy, prolonged menstrual bleeding
– Pelvic pain and pressure
– Frequent urination
– Lower back or leg pain
– Painful sexual intercourse
– Constipation and bloating
– Pregnancy problems, like miscarriage
– Reproductive issues, like infertility

Some warning signs to watch out for include sudden, rapid growth of fibroids, anemia from excessive bleeding, and abdominal swelling if a fibroid outgrows its blood supply. Very rarely, cancerous sarcomas can develop from fibroids.

Large fibroids, usually over 6 to 8 centimeters, can put pressure on the bladder, rectum, or nearby blood vessels. The greater the number of fibroids, the more problematic symptoms tend to become.

Fibroid treatment

If fibroids are not causing any symptoms, treatment is often unnecessary. Your doctor will typically monitor their presence with periodic pelvic exams. However, multiple treatment options can provide relief of fibroid symptoms. Common medical and surgical treatments include:

– Medications – Drugs like nonsteroidal anti-inflammatories (NSAIDs), hormonal contraceptives, and gonadotropin-releasing hormone (GnRH) agonists may help regulate menstruation and relieve pain and pressure. However, medications only provide temporary symptom relief and cannot shrink fibroids.

– MRI-guided ultrasound surgery – This non-invasive procedure uses high-intensity ultrasound waves, guided by MRI, to destroy fibroids without incisions. Recovery time is quicker compared to surgery.

– Myomectomy – This outpatient surgery removes fibroids while leaving the uterus in place. It is an option for women who want to preserve fertility and conceive after treatment. The chances of fibroids recurring after myomectomy are high.

– Hysterectomy – Surgically removing the entire uterus provides a permanent and certain cure for fibroids. It causes permanent infertility. A hysterectomy can be done through the abdomen, vaginally, or with laparoscopic assistance.

– Endometrial ablation – This surgery destroys the uterine lining to reduce heavy menstrual bleeding. However, it cannot remove or treat actual fibroids.

– Uterine artery embolization – Tiny particles are injected into the arteries supplying blood to fibroids, blocking their blood flow and shrinking them. Potential complications include post-procedure pain and infection.

Natural and holistic treatment alternatives to medication and surgery for fibroids also exist. These include:

– Diet and lifestyle changes – Eating an anti-inflammatory diet, exercising regularly, lowering stress, and maintaining a healthy weight can help control symptoms.

– Supplements – Some supplements like vitamin D, curcumin, milk thistle, and omega-3 fatty acids may help balance hormones and reduce inflammation. However, more research is needed on their efficacy.

– Herbal medicine – Herbs like turmeric and green tea, as well as remedies like apple cider vinegar, castor oil packs, and essential oils, may support hormonal balance. However, evidence on their effectiveness is limited.

– Acupuncture – Some findings suggest acupuncture can reduce bleeding and pain associated with fibroids. More research is needed on larger scales.

– Magnetic therapy – Small studies show applying magnets to acupressure points may alleviate fibroid symptoms. Larger controlled studies are still needed.

Vitamin D and fibroids

Growing research indicates that maintaining sufficient blood levels of vitamin D may help reduce the risk for uterine fibroids. For example, a cross-sectional study in over 1200 women found that sufficient serum vitamin D levels were associated with a 32% lower prevalence of fibroids compared to deficient vitamin D status.

Likewise, in a study comparing vitamin D levels in over 400 women with and without uterine fibroids, women with fibroids had significantly lower vitamin D levels. Each 10 ng/mL increase in vitamin D was linked to a 20% lower risk for having uterine fibroids.

Other population studies note similar correlations between healthy vitamin D levels and lower frequency, number, size, and severity of uterine fibroids. While this association does not prove cause and effect, the potential mechanisms behind why vitamin D may protect against fibroid formation include:

– Vitamin D regulates cell proliferation – Active vitamin D binds to receptors on cells called VDRs. This appears to regulate proliferation of smooth muscle cells in tissues like breasts and the uterus. Uncontrolled cell division contributes to the development of tumors like fibroids.

– Anti-inflammatory properties – Vitamin D helps modulate immune cells and cytokine production to reduce inflammation. Inflammation and overproduction of certain growth factors and cytokines may promote fibroid growth.

– Hormone balancing – Vitamin D helps maintain balanced estrogen and progesterone levels. Since fibroids are thought to form from hormonal imbalances where estrogen dominates, vitamin D may help restore optimal estrogen-progesterone ratios.

– Fibrosis inhibition – Vitamin D may inhibit the activation of cells called myofibroblasts that promote formation of fibrotic tissue. Fibroids have excessive amounts of extracellular matrix, a form of fibrous tissue.

However, intervention studies testing the direct effect of vitamin D supplementation on fibroids are very limited at this time. The majority of studies so far are observational and highlight an association that requires further investigation.

Vitamin D’s effects on fibroids

A few small clinical studies provide some early evidence that increasing vitamin D levels through supplementation may support shrinking the size of uterine fibroids:

– In one study, 49 women with symptomatic fibroids were given either vitamin D supplements (50,000 IU capsule weekly) or nothing. After 12 weeks, the vitamin D group had an average fibroid volume reduction of 32.6%. The placebo group saw no change.

– Another study followed 23 women with low vitamin D levels and fibroids. They were given either vitamin D therapy (300,000 IU by injection at study start and 12 weeks) or no treatment. After 24 weeks, the vitamin D group had an average 48% decrease in the volume of their largest fibroid. No changes occurred for the control group.

– A 2020 double-blind trial in Iran gave fifty women who were candidates for hysterectomy either a high-dose vitamin D supplement (300,000 IU) or placebo every two weeks for 12 weeks. By the end of the study, the vitamin D group had significant reductions in both their fibroid size and symptoms compared to placebo. After treatment, 43.5% of the vitamin D group opted not to have hysterectomy surgery.

– A meta-analysis of five studies with 221 participants concluded that vitamin D supplementation for 12-24 weeks may significantly reduce fibroid volume compared to placebo or no intervention. Larger, more rigorous studies are still needed to confirm results.

While these findings show promise, the research is still emerging. Further large-scale clinical trials are needed to establish stronger evidence regarding vitamin D and fibroids. The optimal supplemental dose, frequency, and length of time for reducing fibroid size also requires more investigation.

Most studies used very high doses of vitamin D, often bolus doses of 300,000 to 600,000 IU. Doses this high would only be given under medical supervision to correct vitamin D deficiency. General supplemental doses to maintain healthy levels are closer to 1000-4000 IU daily.

Other benefits of vitamin D

In addition to potential effects against uterine fibroids, maintaining vitamin D sufficiency provides a long list of other health perks:

– Strong bones – Vitamin D promotes calcium absorption and bone mineralization to prevent conditions like osteoporosis.

– Immune regulation – Vitamin D plays a role in innate and adaptive immunity and can reduce risk for illnesses like respiratory infections.

– Heart health – Adequate vitamin D status is linked to decreased inflammation and lower risks of cardiovascular disease, heart attack, and stroke.

– Diabetes – Vitamin D helps regulate insulin secretion. Deficiency has been tied to increased risks for both type 1 and 2 diabetes.

– Cancer prevention – Sufficient vitamin D levels may help prevent development and progression of certain cancers like colorectal, breast, and prostate cancer.

– Autoimmunity – Vitamin D is important for immune tolerance and may reduce risk for autoimmune conditions like multiple sclerosis, rheumatoid arthritis, and lupus.

– Mental health – Optimal vitamin D levels are associated with decreased risks for depression, schizophrenia, and dementia.

– Pregnancy health – Vitamin D promotes healthy placenta and fetal development. Maternal deficiency is linked to gestational diabetes, preeclampsia, and low birth weight babies.

– All-cause mortality – Research connects sufficient 25(OH)D levels to lower risks of premature death from any cause.

With extra health perks like these, there are plenty of reasons to make sure your vitamin D levels are within a healthy target range. Vitamin D deficiency is very common, estimated to affect over 40% of people in the US and one billion people worldwide.

Some groups at higher risk for deficiency include people with darker skin tones, the elderly, those who are overweight or obese, and people with certain medical conditions like Crohn’s disease. To identify deficiency, a 25-hydroxy vitamin D blood test can easily determine your levels.

Vitamin D and fibroids: key takeaways

– Early research indicates vitamin D may help prevent the development and growth of uterine fibroids. However, large-scale clinical trials are still needed.

– Women with healthy vitamin D levels have been observed to have a lower prevalence and severity of uterine fibroids compared to deficient women.

– Potential mechanisms relate to vitamin D’s roles in regulating cell proliferation, hormone balance, inflammation, and fibrosis.

– A few small intervention studies suggest high-dose vitamin D supplementation for 12-24 weeks may reduce fibroid size, but confirmation in larger trials is needed.

– General supplemental doses to maintain sufficient vitamin D are 1000-4000 IU daily. Doses higher than this would only be prescribed under medical supervision.

– Ensuring adequate vitamin D intake/production may offer protections against fibroids while also promoting bone health, immunity, chronic disease prevention, and longevity.

– Checking your blood 25(OH)D level is recommended to evaluate vitamin D status. Optimal values are 30-60 ng/mL, while under 20 ng/mL is considered deficient.

– Vitamin D supplements, omega-3s, herbal remedies, stress management, healthy weight, and exercise may also support natural fibroid treatment. However, claims need more research.

– For troublesome fibroid symptoms, medical procedures like myomectomy, UAE, and MRI-guided ultrasound ablation may provide more reliable shrinking of fibroids. Discuss all your options with your doctor.


Uterine fibroids are extremely common, benign tumors of the smooth muscle in the uterus. While they often cause no problems, larger fibroids can contribute to symptoms like heavy bleeding and pelvic pain and pressure.

Treatment is usually not necessary unless fibroids become bothersome. In addition to medication and surgery, some women may be interested in natural therapies like vitamin D to help slow fibroid growth.

Current research suggests higher blood levels of vitamin D are associated with reduced fibroid prevalence. A few small studies report supplementing with high doses of vitamin D may decrease fibroid size. But large clinical trials are still needed to confirm vitamin D’s efficacy as a fibroid treatment.

Maintaining sufficient vitamin D levels, ideally between 30-60 ng/mL blood levels, provides many additional health benefits too. If you have fibroids, discuss checking your vitamin D status with your healthcare provider. Correcting any deficiency could support your overall health, and possibly foster a small fibroid-shrinking effect. But further research is still pending for definitive answers on vitamin D’s ability to reduce even very large uterine fibroids.

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