Benefits of Soya Isoflavones for Menopause Symptoms

Benefits of Soya Isoflavones for Menopause Symptoms

It is thought that many symptoms of the menopause occur as a result of falling oestrogen levels in the body. When these symptoms - such as hot flushes, night sweats and falling bone density - become severe, the traditional form of treatment is hormone replacement therapy (HRT).

However, HRT is not without its dangers, and in response to this many women choose to investigate alternative treatments.

Of these, soya isoflavones are one of the best-known and most popular options.

What are Soya Isoflavones?

Isoflavones are a group of naturally-occurring chemicals that mimic the overall shape of oestrogen in the body. In many ways they can be thought of as plant-based oestrogen alternatives. It is for this reason that they are sometimes known as “phytoeostrogens” by scientists - with “phyto” meaning “plant”.

When consumed, many experts believe that by binding to oestrogen receptors in the body, they perform a similar role to standard oestrogen. Isoflavones are found in a range of different plants, including red clover and black cohosh, both of which have been used as traditional remedies for generations.

Possibly the most popular plant-based source of these, however, is soya.

It has long been noted that individuals in the East, where soya and soya-based foods like tofu are common dietary constituents, tend to suffer fewer menopause symptoms. Further investigations have revealed the exceptionally high level of isoflavones found in soya.

These days, such is the popularity of soya isoflavones, it is no longer necessary to eat large volumes of soya. Instead, the same benefits can be experienced from specially-made supplements, where simply swallowing a couple of capsules provides a generous volume of isoflavones.

What Do Soya Isoflavones Do for the Menopause?

While soya isoflavones are popular for the menopause, is there any validity to their use? To answer this question we can dive into the world of nutritional science, where a number of studies have aimed to assess the impact of soya isoflavones. In the following sections we'll run through some of the more intriguing discoveries made in recent years as to the potential benefits of soya isoflavones for menopause symptoms.

Hot Flushes & Night Sweats

Soya isoflavones show positive results for helping to reduce the frequency and severity of hot flushes and night sweats.One of the most common symptoms of the menopause is a temporary but uncontrollable feeling of being too hot. These are commonly known as “hot flushes” during daylight hours (or “hot flashes” in the USA) and “night sweats” when experienced in bed.

Despite their differing names, they both stem from the same issue. Principally, falling oestrogen levels during the menopause seem to impact what scientists call “vasomotor function”. Blood vessels at the surface of the skin are a key way in which we control our internal temperature. When we're hot, these blood vessels dilate, allowing hot blood to surge to the surface where the heat can escape.

In contrast, when we're cold these blood vessels constrict, keeping the warm blood deeper within your body. It is believed that hot flushes occur when this system ceases to work as it once did. Instead, hormonal changes can lead to these surface blood vessels suddenly dilating at will, making the individual feel hot, clammy and sweaty.

It goes without saying that such an experience can be uncomfortable and, for some people, embarrassing. Furthermore, they can have a serious impact on sleep quality when they occur during the night.

Possibly the most hopeful potential benefit of consuming soya isoflavones focuses around helping to moderate these hot flushes. While it is rare for them to be eliminated entirely, there is growing evidence that isoflavones may help to reduce the frequency and/or severity of hot flushes.

Over a period of six years, 1,106 women in Japan aged between 35 and 54 were asked to record both their diet and any experiences of hot flushes. The scientists running the research used these food journals to assess total soya isoflavone intake for each participant, before comparing it to the appearance of hot flushes. Of the 101 women that did experience hot flushes within the study period, the results demonstrated that “hot flushes were significantly inversely associated with consumption of soy products”.

But that's not all. A “meta analysis” is considered to be the “gold standard” of scientific investigations. Here the results of numerous previous experiments are collated and combined to provide a more scientifically valid overview of a specific question. Just such a study was carried out on the many investigations addressing the impact of soya isoflavones in menopause-related hot flushes.

The experts carrying out the analysis found that the results were quite uniform, with many different volumes showing positive improvement. They summarized that the “consumption of 30mg/day of soya isoflavones… reduces hot flashes [sic] by up to 50%” but that “the greatest benefit may be realized when the isoflavone-rich food or supplement is taken in divided doses by subjects who experience at least four hot flashes [sic] per day”.

Other studies have aimed to identify the speed of action. A study from Shanghai noted that while soya isoflavones do seem to show effectiveness in repeated tests, it can require an extended period of use before the full impact of isoflavones are experienced. They noted that most studies (especially those showing little or no benefit of soya isoflavones) typically occur over a short period of time, whilst their analyses suggest that soya isoflavones “require at least 48 weeks to achieve 80% of their maximum effects”.

The message here seems to be that we shouldn't be too hasty with measuring the impact of isoflavones. While a number of studies have indicated positive results, it is unlikely that these will be experienced immediately. Instead, one may need to continue treatment for some months before a noticeable impact is experienced.

Cholesterol Levels

Soya isoflavones may help to reduce unhealthy cholesterol levels and protect the heart.Hormonal changes during the menopause can have a considerable impact on cholesterol levels in the body. Repeated studies have demonstrated that high cholesterol is a risk factor for cardiovascular disease; one of the most common sources of mortality in western nations. As a result anything that helps to improve blood chemistry balance is of potential benefit.

Here there is growing evidence that soya isoflavones - when taken in a suitable volume - may help.

But first it is important to understand the basics of cholesterol balance in the body. While cholesterol has developed a bad name over the years, cholesterol itself is not necessarily bad. Quite the opposite; cholesterol is a naturally-occurring substance that is crucial to every cell in the body.

Cholesterol exists in two main forms - LDL cholesterol (often known as “bad” cholesterol) and HDL or “good” cholesterol. The critical element is keeping these two different versions at a suitable balance. Reducing LDL or increasing HDL can both have the same benefit of reducing the risk of cardiovascular problems.

But do soya isoflavones actually have any impact at all on either of these forms of cholesterol?

One scientific study that aimed to answer this question divided 66 menopausal women into three different groups. The first group were the “control” and received no isoflavones. The second and third groups received daily isoflavones in different volumes. After a period of six months, changes to cholesterol were measured to identify any effect of isoflavones. The results showed that both the soya isoflavone groups experienced reductions in bad cholesterol levels as well as increases in good cholesterol.

This led the scientists to summarize that soya isoflavones “may decrease the risk factors associated with cardiovascular disease in menopausal women”.

Other studies have found similar impacts. In one, 80 women were given 100mg of soya isoflavones for a period of four months, before cholesterol changes were measured. The results indicated that low density (“bad”) cholesterol experienced a significant decrease, adding further weight to the possibility that isoflavones may offer benefits to the cardiovascular system.

One of the key reasons why high levels of cholesterol can be harmful is that they can begin to stick to the inner surface of arteries; those critical blood vessels that carry large volumes of blood in or out of the heart. This “plaque” as the build-up is often known, can reduce the diameter of the artery, meaning less blood can pass through and the heart has to work harder.

Another study looked at how “pliable” the arteries of menopausal women are, and whether isoflavones can have any positive impact. While sadly the study group was small - just 21 women - the results did show positive improvements. The volunteers received 80mg of isoflavones per day for a period of 10 weeks, after which their “arterial compliance” was tested. The experts were surprised to find that this measure improved by an astonishing 26% in their test group, which is a similar result to what would be expected from more traditional hormone replacement therapy.

Once again, while the evidence is not conclusive, recent studies do seem to point to some impressive potential benefits for the circulatory system. As many of us could do with improving our cholesterol profile, it might just be that exploring soya isoflavones would be time well spent.

Bone Mineral Density

Bone mineral density might not sound like the most extreme problem experienced by menopausal women, but the impacts can be devastating. Our skeletons are not fixed components of the body; instead they are being continuously broken down and rebuilt. Hormonal changes can impact this process, resulting in bones becoming thinner and, as a result, weaker. This process is typically referred to by doctors as “osteoporosis”. Weak bones can greatly increase the chances of suffering from fractures.

Shocking figures from the National Osteoporosis Foundation in the USA report that approximately half of all women over age 50 will break a bone because of osteoporosis at some point, while the risk of breaking a hip after the menopause is equal to your combined risk of breast, uterine and ovarian cancer.

In other words, while many people don't put much thought into their skeletal health, this is certainly a major factor for ongoing longevity and health for more mature women.

Evidence suggests that a range of lifestyle factors can help to minimize the loss of bone mineral density, including maintaining an active lifestyle involving physical exercise, together with ensuring you are consuming enough calcium, vitamin D and phosphorous.

At the same time, however, soya isoflavones may also offer benefits here too.

Two hundred and three women were provided with either a placebo, a 40mg daily dose of soya isoflavones or an 80mg dose. All were provided with calcium and vitamin D supplements alongside their treatment regime. 12 months later, changes to bone mineral density were measured. It was found that both of the isoflavone groups experienced a “favourable change” in the mineral density of their hip bones. Whilst the impact was reasonably mild, it was still considered “significant” in the fight against osteoporosis.

Once again, this impact is also demonstrated in other studies. For example, a smaller study of Japanese women provided them with either a placebo or 40mg of isoflavones per day for a period of ten weeks. During this time, samples were taken to measure the concentrations of isoflavones in the body, together with chemical signals suggesting the breakdown of minerals from the skeleton. Unsurprisingly, the isoflavone group showed significant improvements in their bone mineral density, while no changes were observed in the placebo group.

The findings seem to suggest that while it would be folly to prioritise the consumption of soya isoflavones over more traditional lifestyle changes, their use may offer just one more tool for the avoidance of osteoporosis as caused by the menopause.

Mental Cognition

Some scientific studies suggest that soya isoflavones may also help to improve some of the mental changes sometimes seen during the menopause.The changes that occur during the menopause aren't just restricted to physical symptoms. There is also some evidence that a fall in oestrogen may also impact certain elements of brain function, such as increasing negative feelings or issues with the memory.

Thirty-three women suffering from the menopause were given either 60mg of soya isoflavones per day or a placebo as a control. This regimen was continued for a period of 12 weeks, after which they underwent a barrage of cognitive tests. The results were startling. The soya isoflavone group experienced improvements in a range of categories, including the recall of pictures, sustained attention and planning.

The experts summarized that “significant cognitive improvements” could be gained from the “consumption of a supplement containing soya isoflavones”.

Other studies have stumbled across potential benefits from ingestion of isoflavones. For example, scientists in Ecuador were carrying out experiments on the impact of soya isoflavones on hot flushes, but found that treatment also seemed to reduce negative emotions in their participants. Indeed, the data demonstrates that 93% of menopausal women experienced a depressed mood at the beginning of the study.

After three months of treatment with 100mg of soya isoflavones per day, however, the number of women suffering from depressive episodes fell to just 28.9% - a significant improvement.

That said, the experts were clear to point out that this impact could come directly from the soya isoflavones themselves, or as an indirect effect from the alleviation of other menopause symptoms.


As with all complementary and alternative treatments, the conclusions are far from clear. Whilst there are numerous studies that demonstrate all manner of positive impacts of soya isoflavones on menopause symptoms, there are others that show far smaller benefits, if any.

Medical professionals right now are quite divided with strong proponents on both sides of the fence.

To a degree it seems possible that these less successful trials may be as a result either of sub-optimal volumes of isoflavones being consumed, or the tests not running for long enough for positive results to develop. What we can say, however, is that there are more than enough positive studies to make soya isoflavones at least worthy of consideration.

If you are struggling with hot flushes, night sweats and other menopause symptoms that are negatively impacting your quality of life then you may want to consider trying isoflavones. In closing, we are all different, and the results of isoflavones may differ from one person to another. Only you can decide if you're willing to try isoflavones as a possible treatment for your condition.

Does soy really help to naturally treat the symptoms of the menopause? If so, how does it help, and how much soy should you be taking to reduce hot flashes and night sweats?