Book Review by Carol Petersen
“Estrogen Matters” by Avrum Bluming and Carol Tavris is a comprehensive guide to understanding the benefits of estrogen therapy, particularly in the context of menopause. However, a critical examination reveals a significant oversight: the authors’ approach to progesterone and medroxyprogesterone acetate (MPA). This review highlights the crucial differences between MPA and natural progesterone, which are essential for effective and safe hormone support.
The Distinction Between MPA and Progesterone
Medroxyprogesterone Acetate (MPA) is a synthetic progestin commonly used in combination with estrogen for hormone replacement therapy (HRT). MPA is known for its stronger effects compared to natural progesterone and is used for various hormonal conditions, including heavy periods and endometriosis. However, research indicates that MPA has several adverse effects compared to natural progesterone. MPA is androgenic, which can lead to undesirable side effects such as acne and hair loss. Moreover, MPA has been shown to negate some of the beneficial effects of estrogen, including its neuroprotective properties and cardiovascular benefits46. Natural Progesterone, on the other hand, has been demonstrated to have neuroprotective effects, enhancing mitochondrial function and protecting against glutamate toxicity, which MPA does not replicate4. Progesterone supports the antiapoptotic protein Bcl-2, crucial for cell survival, a benefit not provided by MPA. Additionally, progesterone does not interfere with the serotonin-enhancing effects of estrogen, unlike MPA, which can block these effects and potentially exacerbate mood disorders4.
Clinical Implications
The Heart and Estrogen/Progestin Replacement Study (HERS) highlighted the risks associated with combination HRT using MPA, including increased venous thromboembolic events and gallbladder disease6. While the study did not show significant differences in cancer rates or mortality, it underscores the need for caution with synthetic progestins like MPA. In contrast, using natural progesterone in HRT could mitigate some of these risks. Progesterone has been shown to enhance the protective effects of estrogen on the cardiovascular system without the detrimental effects seen with MPA36.
Breast Cancer Risk
Observational studies suggest that progesterone may be associated with a lower risk of breast cancer compared to synthetic progestins when used in combination with estrogen. A meta-analysis found that progesterone was associated with a lower breast cancer risk (RR = 0.67, 95% CI 0.55–0.81) compared to synthetic progestins125. This indicates that progesterone might be a safer choice for women undergoing HRT.
Conclusion
While “Estrogen Matters” provides valuable insights into the benefits of estrogen therapy, it falls short by not adequately addressing the superiority of natural progesterone over MPA. The scientific evidence supports the use of progesterone as the preferred progestogen in HRT due to its neuroprotective and cardiovascular benefits, which are not matched by MPA. As such, healthcare providers and patients should consider these differences when making informed decisions about hormone replacement therapy. Recommendation: For women seeking hormone support, it is crucial to opt for natural progesterone over synthetic alternatives like MPA to maximize benefits while minimizing risks. This approach aligns with the latest scientific understanding and could lead to better health outcomes for those undergoing HRT.
References
- PubMed: Progesterone vs. synthetic progestins and the risk of breast cancer
- Endocrine Reviews: Progestogens Used in Postmenopausal Hormone Therapy
- JAMA Oncology: Progesterone and Synthetic Progestin Controversies
- Springer Medizin: Progesterone vs. synthetic progestins and the risk of breast cancer
- Endocrine Reviews: Progestogens Used in Postmenopausal Hormone Therapy
- AAPEC: Progestogens Used in Postmenopausal Hormone Therapy
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