Oral birth control doesn’t cause PCOS or uterine fibroids; wild yam and castor oil are unproven treatments

In July 2024, a claim that oral contraceptive pills are the “number one” cause of polycystic ovary syndrome (PCOS) circulated via an interview with naturopath Barbara O’Neill on social media platforms including Instagram and YouTube. O’Neill, who has a track record of spreading health misinformation, claimed that both conditions were due to hormone “imbalance”. She also recommended wild yam and castor oil to “rebalance” hormones and treat both PCOS and uterine fibroids.

Investigation by the New South Wales Health Care Complaints Commission (HCCC) in 2019 revealed that O’Neill was an unregistered practitioner who lacked any recognized health-related credentials. The commission permanently banned her from providing any health services in Australia after they found that O’Neill actively discouraged the use of antibiotics, vaccinations, and proven treatments for cancer.

This interview originally appeared as part of the George Janko Show and was viewed more than 400,000 times on YouTube. The show previously hosted known spreaders of health disinformation such as Russell Brand and Robert F. Kennedy, Jr..

O’Neill’s claims on uterine fibroids and PCOS are inaccurate, as we’ll detail below.

Oral birth control doesn’t cause or worsen uterine fibroids and polycystic ovary syndrome

Uterine fibroids and polycystic ovary syndrome (PCOS) are two common medical conditions.

Uterine fibroids result from the excessive growth of smooth muscle and connective tissue in the uterus. They’re thought to affect between 40 to 80% of people with a uterus at some point in their lives. While fibroids are often asymptomatic, they can cause symptoms such as heavy menstrual bleeding, frequent or difficult urination, constipation, and pelvic pain. Risk factors for fibroids include obesity, diet high in red meat, and a family history of fibroids.

PCOS is a condition in which the ovaries produce a higher than normal amount of hormones called androgens. Despite being classified as male sex hormones, androgens are also present in female bodies, though at lower levels. This hormonal imbalance can disrupt the menstrual cycle and prevent eggs from leaving the ovary. As a result, this can lead to the accumulation of fluid-filled follicles, or cysts, in the ovaries.

Symptoms of PCOS include heavy, long, or unpredictable periods, excessive hair growth, acne, and weight gain. PCOS is a leading cause of infertility and affects about 15% of people with ovaries. It’s also linked to a higher risk of developing type 2 diabetes and high cholesterol.

The exact causes of both uterine fibroids and PCOS remain unknown, though both conditions appear to be linked to hormonal levels. For example, fibroids often grow during pregnancy when estrogen levels are elevated and shrink after menopause when estrogen levels decrease[1].

Although both conditions are linked to hormonal imbalances, and oral birth control affects hormone levels, it’s inaccurate to claim that oral birth control causes or contributes to either fibroids or PCOS, as suggested by O’Neill.

Science Feedback reached out to the American College of Obstetricians and Gynecologists (ACOG) for details. In an email response, ACOG fellow Michael Belmonte explained:

“While uterine fibroids can grow in the presence of excess estrogens, hormonal birth control, particularly at the dosages available in modern day, do not appear to affect fibroid growth. In fact, hormonal birth control can help to decrease bleeding associated with fibroids, along with other non-contraceptive benefits.”

Regarding PCOS, Belmonte added: “Hormonal birth control has not been shown to cause PCOS.”

Hugh Taylor, a professor of obstetrics, gynecology, and reproductive sciences at Yale University, also told Science Feedback that O’Neill’s claims were “incorrect”. He added that PCOS is actually treated with oral birth control as they help reduce the activity of testosterone (an androgen) and regulate the menstrual cycle.

In summary, oral birth control doesn’t cause or increase the risk of uterine fibroids and PCOS, contrary to O’Neill’s claim. In fact, it can be used to alleviate some of the symptoms of these conditions.

Wild yam and castor oil aren’t proven cures for uterine fibroids or PCOS

O’Neill claimed that wild yam and castor oil can be used to treat uterine fibroids and PCOS. However, Belmonte stated that “there is a lack of sufficient evidence to support these claims”. He warned that it’s “important to discuss with a healthcare professional before starting any supplement, as they may have side effects or interact with other medications [that people are] taking”.

Wild yam (Dioscorea villosa) is often touted as a natural source of estrogen and progesterone useful to alleviate menopausal symptoms. However, its effectiveness remains uncertain, as only a few small studies have investigated it, and their results have been inconclusive. Mount Sinai explained that “several studies have found that wild yam does not reduce the symptoms of menopause, such as hot flashes, or raise levels of estrogen or progesterone in the body”.

Science Feedback explained in a previous review that investigations from the European Medicines Agency (EMA) in 2016 and 2023 showed the lack of health benefits from castor oil—a yellowish oil made from the seeds of the castor bean plant (Ricinus communis). In fact, it is only medically recognized as a laxative.

Conclusion

The claims made by Barbara O’Neill regarding the causes of PCOS and uterine fibroids, as well as her recommendations for wild yam and castor oil to alleviate symptoms of these conditions, aren’t supported by credible scientific evidence. Oral birth control doesn’t contribute to or worsen these conditions, and, in fact, may provide relief for their symptoms.

Similarly, the purported benefits of wild yam and castor oil in treating these conditions lack reliable scientific backing. While wild yam is sometimes marketed for menopausal relief, its efficacy remains unproven. Castor oil is only medically recognized for its use as a laxative.

While uterine fibroids can grow in the presence of excess estrogens, hormonal birth control, particularly at the dosages available in modern day, do not appear to affect fibroid growth. In fact, hormonal birth control can help to decrease bleeding associated with fibroids, along with other non-contraceptive benefits.

Polycystic ovary syndrome is a disorder characterized by an excess of a specific category of hormones, called androgens, impairment of ovulation (release of an egg from the ovaries), and multiple ovarian cysts. While the cause is not completely clear, genetics and obesity tend to be the biggest factors. Hormonal birth control has not been shown to cause PCOS.

Home remedies such as castor oil or wild yam have been touted as miracle cures for various hormonal concerns, as they claim to be natural sources of hormones or help to “rebalance”, but there is a lack of sufficient evidence to support these claims. It is important to discuss with a healthcare professional before starting any supplement, as they may have side effects or interact with other medications you are taking.

Both the claim that the contraceptive pill is “the number one cause” of PCOS and that a combination of castor oil and wild yam can cure PCOS and uterine fibroids are incorrect.

Fibroids grow in response to estrogen and progesterone, however the levels [of these hormones] are not higher in women with [fibroids]. It is a mutation in the fibroid cells that makes them grow abnormally. Lowering hormones dramatically works but there is no evidence for the “balancing” of hormones.

PCOS is treated with oral contraceptives. They help to reduce testosterone action and regulate [menstrual] cycles.

REFERENCES

• 1 – Reis et al. (2016) Hormones and pathogenesis of uterine fibroids. Best Practice & Research Clinical Obstetrics & Gynaecology.
• 2 – Emanuel et al. (2022) A review of the hormones involved in the endocrine dysfunctions of polycystic ovary syndrome and their interactions. Frontiers in Endocrinology.