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Exploring The Connection Between Fibroids And Obesity

 

Fibroids_weightgainThe relationship between weight and uterine fibroids (also known as leiomyomas) is a complex one. However, while it is not fully understood, a link between obesity – which is typically defined by a Body Mass Index (BMI) ≥24 – and fibroid risk has been identified in multiple research studies. In fact, data suggest that obese women have two to three times the risk of developing fibroids than women of average weight.

Racial Disparities In The Impact of Obesity

Some research suggests that the relationship between BMI and fibroid risk differs between black women and white women. One study produced evidence that premenopausal black women may have higher ovarian hormone levels than white women (Woods et al., 1996). Another revealed that in black women, estradiol levels decrease as BMI increases in black women, whereas this was not the case for white women (Manson et al., 2001).

The Black Women’s Health Study, an ongoing prospective cohort study in the U.S. that was initiated in 1995, found the prevalence of obesity (BMI ≥30 kg/m2) to be nearly twice as high in black women as in white women. The incidence of uterine fibroids is also significantly greater in black women than white women, and the researchers involved concluded that this was not a coincidence: they hypothesized that a connection with the weight factor could partially explain the disparity in the disease burden. Looking more deeply at the results of the cohort study, the research team of Wise et al. noted that “weight gain was positively associated with risk among parous women (those who have given birth) only”.

Understanding the Hormone Connection

To understand the role that weight plays in fibroid development, one must start by looking at the common denominator: hormones. Ovarian hormones, particularly estrogen, play a key role in the development of fibroids. Obesity has been tied to hormonal and metabolic changes in women of reproductive age, included altered estrogen metabolism.

In a May 2012 article for Today’s Dietitian, Krystene DiPaola, MD, a reproductive endocrinologist and infertility specialist at the University of Cincinnati Academic Health Center, explains, “We do know that fibroids respond to estrogen, and that estrogen isn’t produced only in the ovaries but also in peripheral fat in the form of estrone,” she explains. “The estrone can, in higher doses such as in overweight women, affect fibroid growth and cause them to be more symptomatic.”

Does Diet Make a Difference?

The question then becomes, is it possible for an obese woman to minimize the occurrence or recurrence of her fibroids by losing weight? Unfortunately, research has not yet yielded a definitive answer to this question. However, some study data suggest that diet modification – and particularly the weight loss that may result – can make a difference in the presentation of fibroids. Because hormones are the driving force behind fibroid development, dietary choices that promote hormonal balance can potentially impact the development of fibroids and the severity of their associated symptoms.

DiPaola believes any nutritional modification that may lower peripheral fat stores, and therefore reduce estrogen production from those fat stores, only helps women with symptomatic fibroids. “In terms of my personal opinion,” DiPaola says, “the dietary component towards the treatment of fibroids can do nothing but help and may augment the traditional therapies to treat this condition.”

 

>> SEE ALSO:  The Fibroids-Diet Connection

 

SOURCES:

Takeda, T. et al. “Relationship Between Metabolic Syndrome and Uterine Leiomyomas: A Case-Control Study”, Gynecologic and Obstetric Investigation. July 2008; 66:14–17

Woods, MN. et al. “Hormone levels during dietary changes in premenopausal African-American women”,
Journal of the National Cancer Institute. Oct 1996; 88(19): 1369-74

Manson, JM. et al. “Racial differences in sex hormone levels in women approaching the transition to menopause”, Fertility and Sterility. Feb 2001; 75(2): 297-304

Wise, L. et al. “Influence of Body Size and Body Fat Distribution on Risk of Uterine Leiomyomata in U.S. Black Women”, Epidemiology. May 2005; 16(3): 346-354

Tempest, M. “Uterine Fibroids and Nutrition — Studies Suggest Healthful Dietary Modifications May Cut Risk and Ease Symptoms”, Today’s Dietitian. May 2012; 14(5): 40 http://www.todaysdietitian.com/newarchives/050112p40.shtml#sthash.tuDCxUd2.dpuf

 

 

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What Causes Fibroids: The Known Risk Factors

 

Uterine fibroids, also known as leiomyomas, are the most common benign pelvic tumor in pre-menopausal women. According to the American Society for Reproductive Medicine, uterine fibroids will affect 8 in 10 African American women and 7 in 10 Caucasian women before menopause.

Despite the prevalence of the condition and the plethora of studies that have sought to explain it, the cause of fibroids is still not fully understood. However, evidence suggests that fibroids’ development can be attributed to a combination of genetic and hormonal traits.

Hormonal Risk Factors

The link between fibroids and hormones is well documented. Specifically, it is known that fibroids are estrogen-dependent. As a result, fibroids grow during a woman’s childbearing years, while the ovaries are naturally producing estrogen, and they typically shrink after the onset of menopause, when levels of the hormone drop. The influence of hormones on fibroid growth renders the following traits “risk factors”:

Age – The risk of fibroids increases with age, up to the point of menopause. Once menopause is reached and the body’s estrogen production naturally declines, fibroids typically shrink and – in many cases – disappear entirely.
Contraceptive use – Women who began taking oral contraceptives before the age of 16 are at a greater risk of developing fibroids. However, studies have revealed that using progestin-only injectable contraceptives is associated with a reduced risk of fibroids.

Obesity – Researchers believe that being obese increases the risk of uterine fibroid development, possibly due to the association between obesity and high circulating estrogen levels.


Genetic Risk Factors

Race – The connection between race and fibroids isn’t entirely understood, but an abundance of clinical data shows it to be a significant risk factor. Black women are nearly three times more likely to develop fibroids than white women. Furthermore, research has shown that black women tend to have larger and more symptomatic fibroids than women of other races.

Family health history – Researchers and medical practitioners have long observed a familial predisposition to fibroids. To date, various clinical studies have identified over 100 specific genes as having potential links to fibroid development. OB-GYN Dr. Donald Galen frequently observes the genetic trend in his fibroid patients: “It is common for a woman with fibroids to have a history of her mother, maternal aunt, or sister who also have fibroids, ” he says.


Other Risk Factors

Certain lifestyle and environmental traits have been thought to play a role in the development of fibroids, though clinical studies have yielded somewhat contradictory results.

Diet – Research has shown that women who eat a vegetarian diet are less likely to develop fibroids than women whose diets include meat. Some studies suggest that consuming more fruits, vegetables, and low-fat dairy products could reduce the risk of developing fibroids; however, the effectiveness of changing dietary habits in slowing the growth of existing fibroids or preventing the development of new fibroids has not been conclusively established.
While the exact cause of fibroids remains unclear, existing research points to a confluence of genetic and hormonal traits. Given the prevalence of the condition of uterine fibroids, its epidemiology will undoubtedly continue to be the subject of research. The risk factors that have been established, however, help us to understand who is susceptible to developing fibroids and what physical and lifestyle changes may prevent or minimize fibroids’ occurrence.

 

SOURCES:

  1. American Society for Reproductive Medicine, “Fibroid Tumor Video Transcript”, ReproductiveFacts.org: 2011.
  2. Retrieved July 13, 2015, from http://www.reproductivefacts.org/Fibroid_tumor_video/
  3. Stewart, E. “Uterine Fibroids”, New England Journal of Medicine. 2015; 372: 1646-55.
  4. Wise, L. et al. “Age-Specific Incidence Rates for Self-Reported Uterine Leiomyomata in the Black Women’s Health Study”, Obstetrics & Gynecology. Mar 2005; 105(3): 563–568.
  5. Levy, B., “Modern management of uterine fibroids”, Acta Obstetricia et Gynecologica. April 2008; 87: 812-823
  6. Burbank, F. Fibroids, Menstruation, Childbirth, and Evolution, pp. 89-90. Wheatmark, 2009. Tucson, AZ.

Fibroids Are Not Color Blind

Over the years, researchers have examined the epidemiological connection between a wide variety of patient characteristics and the occurrence of uterine fibroids, seeking to identify risk factors. Age, weight, diet, geographic location, lifestyle factors like cigarette smoking, medical conditions, and history of childbirth have all been studied, and many have been correlated with fibroids in one way or another. But time after time, study after study, one characteristic has stood out as a major indicator of fibroid risk: race. And the conclusion that researchers have consistently reached is this: uterine fibroids (also known as leiomyomas) disproportionately affect women of color.

Certain, specific differences have been seen in the cases of black women: research shows that, in comparison to white women, black women tend to develop a larger number of fibroids and experience more fibroid-related symptoms. A study published in 2013 by the American Society for Reproductive Medicine reported that, “African-American women had substantially more fibroids” with an average of 9.9 fibroids compared to the Caucasian subjects’ average of 4.5 fibroids. Additionally, Weiss et al. conducted a multi-ethnic, multisite, longitudinal study of 3,302 women ages 42-52 and concluded that “previously diagnosed leiomyomas were presenting symptoms more frequently in African-American woman than Caucasian women (85% vs. 63%)”.

The racial disparity in fibroid occurrence isn’t fully understood. The research that exists mostly defines the relative risk of the condition in terms of black and white. Obviously, black and white women aren’t the only ones affected by uterine fibroids. While very little data exists on the differences in susceptibility and symptoms between other ethnicities, a 2011 study conducted by the U.S. Armed Forces identified the relative risk of fibroids for multiple ethnic groups. The study looked at the population of active military women who were diagnosed with fibroids between 2001 and 2010: 11,931 cases were recorded. The researchers concluded that, relative to the white, non-Hispanic population, the risk of fibroids was slightly higher (1.1 times) for Hispanics and Asians/Pacific Islanders, and slightly lower (.9 times) for American Indians/Alaskan Natives. By comparison, African American women were 4.4 times more likely to have the same diagnosis, and women in the ethnic category of “Other” had almost double (1.9 times) the incidence of fibroids. These findings are depicted in the graph below.

Fibroids--race_MSMRgraph

As of now, there are no clear answers to explain why symptoms and presentation of uterine fibroids are different in women of color. However, the connection between fibroids and race is certainly a topic of interest to researchers, physicians and fibroid patients alike, and one that continues to be the subject of medical research.

Sources:

  1. Schwartz, S.M. “Epidemiology of uterine leiomyomata”, Clinical Obstetrics & Gynecology. June 2001; Vol.44(2):316-26
  2. Moorman, P.G. et al. “Comparison of characteristics of fibroids in African American and white women undergoing premenopausal hysterectomy”, Fertility & Sterility, March 2013; Vol.99(3)768-776>
  3. Weiss, G. et al. “Racial differences in women who have a hysterectomy for benign conditions”, Women’s Health Issues, May-June 2009; Vol.19(3):202-10
  4. Eltoukhi, H.M. et al. “The health disparities of uterine fibroid tumors for African American women: a public health issue”, American Journal of Obstetrics & Gynecology, March 2014; Vol.210(3)
  5. “Uterine Fibroids, Active Component Females, U.S. Armed Forces, 2001-2010”, Medical Surveillance Monthly Report, December 2011; Vol.18(12):10-13

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