Phytoestrogens – how to use these fascinating plant phytonutrients in menopause
Some of the most commonly discussed plant compounds associated with perimenopause and menopause are phytoestrogens. With a structure similar to oestrogens, phytoestrogens are naturally occurring plant compounds that weakly bind to human oestrogen receptors.
- Eating foods rich in phytoestrogens can be part of a balanced and healthy diet, and provides protein, fibre, vitamins and minerals.
- The effect of phytoestrogens on menopausal hot flushes varies between individuals, as only a third to a half of women have the gut bacteria that convert the phytoestrogens to a more potent form.
- Some studies have shown potential benefits of phytoestrogens in regard to cardiovascular risk, bone density and menopausal symptoms.
- There is growing evidence to suggest that phytoestrogens may help with bone and cardiovascular health, but this remains unclear.
- It is not recommended that woman at high risk of breast cancer, or who have had breast cancer, take soy supplements or highly processed soya.
Phytoestrogens can be helpful because they bind our oestrogen receptors weakly, meaning they can help mimic oestrogen in times when natural levels are low; or block stronger oestrogens from binding. Although they do stimulate oestrogen receptors, they do so in a much weaker way than our own endogenous oestrogen.
The different types of phytoestrogens include:
- Isoflavones (such as genistein and daidzein)- found in soy and other legumes such as lentils, beans, peas, chickpeas, mung beans, alfafa and red clover.
- Coumestans -found in alfalfa and clover sprouts, and sprouted legumes such as mung beans and soy sprouts.
- Lignans -found in linseeds/ flaxseeds, grains and vegetables.
Moderately including phytoestrogens in your diet is beneficial and may be helpful in reducing some menopausal symptoms. A diet containing legumes, beans, flax seeds and organic non GMO fermented soy has nutritive value, and can be part of a balanced Mediterranean diet which is to be recommended as a healthy and sustainable food plan. It is best to avoid highly processed soya - tofu, edamame and tempeh are safer alternatives and including these foods in your diet is also safe if you are taking HRT.
Dietary soya products and isolated isoflavones supplements are not the same and can have different effects in the body, with isoflavone supplements being more concentrated. Isoflavone supplements are the phytoestrogens used in the majority of studies, either extracted from soy beans or red clover; and have been shown to have modest efficacy in some menopausal symptoms in particular hot flushes, poor brain function, depression and anxiety. According to a review by The Journal of The North American Menopause Society in 2011, the minimal dose at which significant benefit was seen was 50 mg of total isoflavones/day, which could be considered the starting dose. A trial of 12 weeks was generally sufficient to see whether improvement would occur. Safety was found with long-term intake of up to 150 mg isoflavones per day ingested for the duration of at least 3 years.
(Consensus: soy isoflavones as a first-line approach to the treatment of menopausal vasomotor complaints by M Schmidt · 2016)
There are two different types of oestrogen receptors within our bodies, alpha oestrogen receptors (ERα ) and beta oestrogen receptors (ERβ ). ERα are present mainly in mammary glands (breasts), uterus, bone, liver, and fat tissue. By contrast, ERβ are found mainly in the bladder, colon, fat tissue, and immune system. Both types are found in the cardiovascular and nervous systems. ERβ seems to have a more profound effect on the nervous and immune systems, and ERα is more responsible for promoting cell growth in the breast and uterus.
Most research on the binding of phytoestrogens to oestrogen receptors has been conducted with the major soy isoflavones genistein and daidzein, and it has been found that genistein seems to have a higher affinity to bind to ERβ and daidzein has less, meaning it has been observed to relatively affect the ERα receptors more.
The gut microbe plays an essential role in how phytoestrogens are broken down in the body and utilised. Lignans from fruit, vegetables and flax seeds are converted by bacteria in the gut, which helps their absorption into the body. Both isoflavones and lignan metabolism is dependent on gut flora and dietary fibre which affects the absorption, reabsorption and excretion of oestrogens and phytoestrogens. Only about 30% of North American women have the ability to metabolize daidzein to equol, which is an oestrogen-like compound that binds to both oestrogen receptors and has been shown in some studies to help reduce menopausal symptoms like hot flushes.
After phytoestrogens are broken down in the gut and transported to the liver and into the body, they have also been shown to have neuroprotective effects and some general antioxidant and anti-inflammatory effects, decreasing allergic responses and autoreactive immune responses.
It has long been noted that Asian women have lower bone density and lower calcium intake than Caucasian women and yet have stronger bones and fewer osteoporotic fractures during menopause. They also have a lower risk of developing cancer and heart disease. A diet rich in phytoestrogens has been thought to be a possible reason. The link between eating phytoestrogens and a decreased risk of developing breast cancer seems mostly to be seen in women who have been consuming phytoestrogens through their daily diet since childhood, and in the form of traditional and fermented food sources.
Studies have found evidence that complicates the relationship between phytoestrogens and breast cancer however this does focus on the highly processed and concentrated soya isoflavones. Evidence indicates that these products may show a proliferative effect, encouraging tumour growth. This may depend on several factors - age, phytoestrogen type, cancer subtype, concentration and dose have all been observed as factors that determine how these phytoestrogens will affect breast cancers. Until there is more clarity it is best to avoid highly processed soy or soya isoflavones supplements if there is a history of breast cancer.
A diet containing food sources in moderation is however a safe option and lignans found in flax seeds, fruits, grains and seeds do have some positive research to support their use and may help to reduce tumour cell growth. Ground flaxseeds are also rich in Omega 3 essential fatty acids and fibre and can be taken at a dose of two tablespoons per day. They can be added to porridge or mixed into smoothies.Dr Sally Moorcroft
Integrative and Functional Medicine Doctor
Orchard Barn Integrative Health Centre, Stallingborough, Grimsby, NE Lincolnshire.