Can soy help manage menopause symptoms?
Soy can be a confusing topic, especially in regard to women’s health during menopause. What is the truth about soy and can it help manage menopause symptoms?
To answer these questions, we need to examine the scientific and medical literature. Let’s explore the evidence and see what it says about soy.
What is soy and where will you find it in your diet?
Soy beans grow on a small leafy plant, you can eat the young beans as they are, in this form they referred to as edamame. The mature beans can be processed into other products, of course the most common being tofu. Other soy products include soy milk, soy sauce, tempeh, miso and natto, it’s also commonly found in fake meat products and as an addition to packaged foods like breads, cereals and treats.
What are phytoestrogens and isoflavones?
Phytoestrogen simply means plant (phyto) oestrogen (the hormone oestrogen), so phytoestrogens are any compound found in plants that have a similar effect in the body to oestrogen. Any compound that mimics oestrogen is said to have an oestrogenic effect. Phytoestrogens are commonly associated with soy, yet they are also found in many other foods such as legumes, flaxseed, wholegrains, fruits and vegetables.
There are many types of phytoestrogens, those found in soy are called isoflavones.
Isoflavones are a group of compounds that are classed as phytoestrogens, and although they can be found in a number of different plants and foods, soy products provide the largest amounts of isoflavones in the human diet.(1, 2) There are many types of isoflavones however, the most prominent are genistein, daidzein, and glycitein.
The way the soy bean is processed can greatly affect the amount of isoflavones present in the final product. Certain methods will reduce the isoflavone content while others will preserve or even concentrate it.
In this article, we will be discussing soy isoflavones. However as discussed above there are many other sources of phytoestrogens, please keep in mind other types may have different effects within the body.
How is soy processed in the body?
Soy isoflavones have a similar chemical structure to the human oestrogen hormones. Because of this they can bind to oestrogen receptors in the body. This is where it gets a little more complicated, but hang in there because it will explain why there is so much confusion around soy.
Oestrogen, like all other hormones, helps regulate certain bodily functions. However, it is the level of circulating hormone that will predict the effects it will have within the body. There is a very complicated and delicate balance going on at any one time. Too little oestrogen can have negative health consequences yet so can high levels of the very same hormone.
While adequate oestrogen levels are essential for sexual maturation in females, bone formation, cardiovascular and brain health. Low levels, as seen during menopause, can result in reduced bone density, loss of libido, can affect mood and sleep and of course produce menopausal symptoms such as hot flushes. High levels on the other hand are suspected to increase the risk of developing certain hormone sensitive cancers such as breast cancer. This apparent link between oestrogen and cancer is where the fear of soy products originates. And rightfully so, if high oestrogen levels can cause health problems then would a diet high in isoflavones (remember this is a type of phytoestrogen) also cause health problems?
As with most things in nutrition and science, it’s not so straight forward. The brain ache of understanding soy continues. Soy isoflavones are slightly different to the actual human oestrogen hormone and while they can mimic the effects of oestrogen in some tissues and organs they can also block the effects oestrogen has on other parts of the body. Additionally, they have a weaker effect on most cells than actual oestrogen.
Oestrogen blocking effects on breast tissue and on the uterus can protect against cancers. That’s why scientists are so interested in the oestrogen blocking effects of soy isoflavones. On the other hand, the oestrogen activating effects in other areas of the body may help maintain bone density, cardiovascular health and reduce the severity of hot flushes. Again, this is where the interest arises when considering soy products and their possible ability to counteract menopausal symptoms.
Interesting right!? But wait, this doesn’t really answer the question does it. Will soy help or hinder women going through menopause?
Harmful or helpful?
Unfortunately, there is no definitive answer to this question. There are many conflicting views in medical circles as to whether isoflavones are effective for dealing with menopausal symptoms.
When it comes to the safety of soy, it seems soy consumed as part of the diet does not produce any negative health consequences. Recently after a comprehensive review of all available studies the European Food Safety Authority found that isoflavones in menopausal and post-menopausal women did not have any adverse effects on breast tissue, the uterus or thyroid function.(1) Another study looked at phytoestrogen intakes in menopausal women from over 9600 women (92 individual studies) and found there were no serious negative health effects from phytoestrogens compared to a placebo.(2) Other researchers contradicted these findings slightly by saying more research is needed to make a definitive conclusion.(3)
Let’s look at specific menopausal symptoms one by one.
A number of studies suggest soy isoflavones supplements can help reduce the duration and severity of hot flush episodes and vaginal dryness.(6, 7, 8, 9, 10) However, these results are not conclusive. Some women will benefit more than others from soy isoflavone treatments, a trial period of 6 weeks should be enough to determine if soy isoflavones will work for you.
There is not enough evidence to suggest soy isoflavones will help maintain bone density.(11, 12) Consuming sufficient calcium and participating in weight bearing exercises are likely more effective to protect against bone loss.
Some evidence suggests soy intake and supplementation may benefit cardiovascular health in post-menopausal women.(7, 13) This is still an emerging age of research and again no definitive conclusion has been reached yet.
This does not necessarily encompass genetically modified (GM) soy, the oestrogenic properties of GM soy require more research. Any difference in the effects of GMO soy, compared to conventionally grown soy, are likely from the pesticides used rather than the actual genetic modification.(14, 15)
The answer to the question is soy beneficial or harmful for menopausal women. Well, it does appear that eating moderate amounts of soy based products is unlikely to have any harmful effects on healthy women. As to the beneficial effects more research is needed to conclusively answer this question. Whether soy will be beneficial for you depends on many factors including your age, your current health status, the type of soy products or supplements consumed and even if you have a certain bacteria present in your gut.
1.Munro IC, Harwood M, Hlywka JJ, Stephen AM, Doull J, Flamm WG, et al. (2003) Soy isoflavones: a safety review. Nutrition Reviews; 61, 1-33.
2.Kurzer MS, Xu X (1997) Dietary phytoestrogens. Annual review of nutrition; 17, 353-81.
3.Food A (2015) Risk assessment for peri-and post-menopausal women taking food supplements containing isolated isoflavones. EFSA Journal; 13.
4.Tempfer CB, Froese G, Heinze G, Bentz E-K, Hefler LA, Huber JC (2009) Side effects of phytoestrogens: a meta-analysis of randomized trials. The American journal of medicine; 122, 939-46. e9.
5.Rietjens IM, Louisse J, Beekmann K (2017) The potential health effects of dietary phytoestrogens. British journal of pharmacology; 174, 1263-80.
6. Franco OH, Chowdhury R, Troup J, Voortman T, Kunutsor S, Kavousi M, et al. (2016) Use of plant-based therapies and menopausal symptoms: a systematic review and meta-analysis. Jama; 315, 2554-63.
7.Clarkson TB, Utian WH, Barnes S, Gold EB, Basaria SS, Aso T, et al. (2011) The role of soy isoflavones in menopausal health: report of The North American Menopause Society/Wulf H. Utian Translational Science Symposium in Chicago, IL (October 2010). Menopause; 18, 732-53.
8. Taku K, Melby MK, Kronenberg F, Kurzer MS, Messina M (2012) Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause; 19, 776-90.
9.Chen M, Lin C, Liu C (2015) Efficacy of phytoestrogens for menopausal symptoms: a meta-analysis and systematic review. Climacteric; 18, 260-9.
10.Jacobs A, Wegewitz U, Sommerfeld C, Grossklaus R, Lampen A (2009) Efficacy of isoflavones in relieving vasomotor menopausal symptoms–a systematic review. Molecular nutrition & food research; 53, 1084-97.
11.Ricci E, Cipriani S, Chiaffarino F, Malvezzi M, Parazzini F (2010) Soy isoflavones and bone mineral density in perimenopausal and postmenopausal Western women: a systematic review and meta-analysis of randomized controlled trials. Journal of Women’s Health; 19, 1609-17.
12.Lagari VS, Levis S (2013) Phytoestrogens in the prevention of postmenopausal bone loss. Journal of Clinical Densitometry; 16, 445-9.
13.Dong J-Y, Wang P, He K, Qin L-Q (2011) Effect of soy isoflavones on circulating C-reactive protein in postmenopausal women: meta-analysis of randomized controlled trials. Menopause; 18, 1256-62.
14.Padgette SR, Taylor NB, Nida DL, Bailey MR (1996) The composition of glyphosate-tolerant soybean seeds is equivalent to that of conventional soybeans. The Journal of Nutrition; 126, 702.
15.Duke SO, Rimando AM, Pace PF, Reddy KN, Smeda RJ (2003) Isoflavone, glyphosate, and aminomethylphosphonic acid levels in seeds of glyphosate-treated, glyphosate-resistant soybean. Journal of Agricultural and Food Chemistry; 51, 340-4.