Soy Isoflavones For Menopause: Benefits, Side Effects & Common FAQS

What are Soy Isoflavones?

Soy isoflavones are dietary supplements derived from soybeans and contain phytoestrogens. Phytoestrogens are compounds derived from plants and are similar in structure to estrogen¹.
Because soy isoflavones can bind to estrogen receptors in our bodies, they can mimic the hormone and kickstart the processes that estrogen is responsible for. Some research on animals suggests that isoflavones may even support bone health².

Benefits of Soy Isoflavones for Menopause

Before the advent of soy isoflavones for menopause, many women used hormone replacement therapy to manage menopause symptoms. However, recent research has revealed that prolonged use of some HRT methods may increase the risk of serious conditions such as blood clots, stroke, and breast cancer³.

Phytoestrogen soy isoflavones can be an alternative method for treating menopause symptoms that yields similar results. A 2021 analysis of the effect of soybeans on menopausal hot flashes, found that the women who added half a cup of soybeans to a low-fat, vegan diet experienced an up to 79% reduction in menopause hot flashes⁴.

Menopausal women who use isoflavones from soy for menopause may experience a:

• Decrease in hot flashes
• Improvement in mood
• Reduction in fatigue levels
• Preservation of bone strength⁵

Possible side effects of soy isoflavones

Despite soy isoflavones being a natural way to manage menopause symptoms, they also may carry some side effects to be aware of. Examples include⁶:

• Stomach upset
• Constipation or diarrhea
• Gas
• Allergic reactions

This list of side effects related to the use of soy isoflavones is not exhaustive, if they persist it’s never a bad idea to reach out to a healthcare professional for guidance.

Using soy isoflavones properly 

While contemplating if isoflavones are good for you, you should:

• Take soy isoflavone supplements with food. Food in your stomach reduces the risk of irritating your gastrointestinal system as it breaks down your supplements.
• Follow product instructions carefully. Always pay close attention to dosage guides to ensure you take the proper amount of your supplement at the right time of day.
• Talk to your doctor. If you have health concerns that may impact how you use soy isoflavone, such as a pre-existing hormonal condition or an allergy to soy, it’s a good idea to talk with a doctor before getting started⁶.

Common FAQs About Isoflavones

• Do soy isoflavones cause cancer?
• Research has found that soy isoflavones may even reduce the risk of breast cancer⁷.
• What menopause symptoms can isoflavones help with?
• Research suggests that isoflavones can help to reduce hot flashes, improve mood, and lessen fatigue⁵. These changes can help you feel more stable throughout each stage of menopause.
• Do isoflavones increase estrogen levels?
• Consuming soy isoflavones does not necessarily increase estrogen levels in the body; instead, it introduces similar compounds that can mimic estrogen. Research shows that isoflavones work by emulating estrogen rather than stimulating its production⁸.
• Is estrogen the same as isoflavones?
• Isoflavones are not the same as estrogen produced in the body. Isoflavones are a structurally similar, plant-based type of estrogen¹. When consumed, they simply mimic the estrogen that our bodies typically create rather than attempting to replace it, like estrogen hormone replacement therapy would do.
• Is soy the best source of isoflavones?
• Soy is the richest source of isoflavones in the human diet. Other sources of isoflavones are fruits, vegetables, beans, legumes, nuts, and seeds¹.
• Are isoflavones safer than hormone therapy?
• Only a healthcare professional can help you determine what risks hormone replacement therapy may hold for you. In general, soy isoflavones may be considered safer since they are not linked to any major side effects⁶. Still, whether soy isoflavones are a safer option for you depends on your circumstances.
• How long does it take for soy isoflavones to work?
• Although results vary, studies suggest it can take up to 13 weeks for soy isoflavones to reach about half of their maximal effects. Around 48 weeks of treatment or more were necessary to see over 80% of the treatment’s effects⁹.
• Are there soy isoflavone drug interactions?
• Soy isoflavones have drug interactions with¹⁰:
• Repaglinide
• Valproic acid
• Celecoxib
• Theophylline
• Danofloxacin
• Imatinib
• Paclitaxel
• Midazolam
• Carbamazepine
• Omeprazole
• If this is a potential concern for you, be sure to speak with a doctor.

Using Soy Isoflavones for Menopause: Final Thoughts

Soy isoflavones are phytoestrogens that are structurally similar to estrogen. They have estrogen-like effects in the body that may help women in menopause manage symptoms like hot flashes, mood swings, fatigue, and more⁵. Your doctor can help you decide whether soy isoflavones are an appropriate treatment method for you.

References:

1. Krizová, L. et al. (2019, March 19) Isoflavones. Molecules 24(6):1076. DOI: 10.3990/molecules24061076. Retrieved July 19, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6470817/  
2. Mathey, J. et al. (2007) Modulation of soy isoflavones bioavailability and subsequent effects on bone health in ovariectomized rats: the case for equol. Osteoporos Int 18:671-679. DOI: 10.1007/s00198-007-0351-y. Retrieved July 19, 2023, from https://link.springer.com/article/10.1007/s00198-007-0351-y  
3. Mayo Clinic Staff. (n.d.) “Hormone therapy: Is it right for you?” Mayo Clinic. Retrieved July 19, 2023, from https://www.mayoclinic.org/diseases-conditions/menopause/in-depth/hormone-therapy/art-20046372 
4. Barnard, N.D. et al. (2021, October) The Women’s Study for the Alleviation of Vasomotor Symptoms (WAVS): a randomized, controlled trial of a plant-based diet and whole soybeans for postmenopausal women. Menopause 28(10):1150-1156. DOI: 10.1097/GME.0000000000001812. Retrieved July 19, 2023, from https://journals.lww.com/menopausejournal/Fulltext/2021/10000/The_Women_s_Study_for_the_Alleviation_of_Vasomotor.12.aspx 
5. Ahsan, M. and Mallick, A.K. (2017, September) The Effect of Soy Isoflavones on the Menopause Rating Scale Scoring in Perimenopausal and Postmenopausal Women: A Pilot Study. J Clin Diagn Res 11(9):FC13-FC16. DOI: 10.7860/JCDR/2017/26034.10654. Retrieved July 19, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5713750/ 
6. Cleveland Clinic. (n.d.) “Soy Isoflavones Oral Dosage Forms.” Retrieved July 19, 2023, from https://my.clevelandclinic.org/health/drugs/20099-soy-isoflavones-oral-dosage-forms 
7. Boutas, I. et al. (2022, March-April) Soy Isoflavones and Breast Cancer Risk: A Meta-analysis. In Vivo 36(2):556-562. DOI: 10.21873/invivo.12737. Retrieved July 19, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8931889/ 
8. Messina, M.J. and Wood, C.E. (2008, June 3) Soy isoflavones, estrogen therapy, and breast cancer risk: analysis and commentary. Nutr J 7(17). DOI: 10.1186/1475-2891-7-17. Retrieved July 19, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2443803/ 
9. Li, L. et al. (2014, October 15) Quantitative efficacy of soy isoflavones on menopausal hot flashes. British Journal of Clinical Pharmacology 79(4):593-604. Retrieved July 19, 2023, from https://doi.org/10.1111/bcp.12533 
10. Soyata, A., Hasanah, A.N. & Rusdiana, T. (2021, December 31) Isoflavones in Soybean as a Daily Nutrient: The Mechanisms of Action and How They Alter the Pharmacokinetics of Drugs. Turk J Pharm Sci 18(6):799-810. DOI: 10.4274/tjps.galenos.2020.79106. Retrieved July 19, 2023, from https://pubmed.ncbi.nlm.nih.gov/34979737/