Search

Phytoestrogens

What are phytoestrogens?

Phytoestrogens are natural, plant-derived compounds present in a healthy and balanced diet. They are most notably found in soy products as well as flaxseeds, sesame seeds, wheat, oats, lentils, carrots, apples and many other fruit and vegetables. They get their name from being oestrogen-like in structure and function and being present in plants. Oestrogen is the predominant female hormone involved in reproduction including roles in sexual maturity and menstruation. Oestrogen is produced naturally by the body but can be present in some foods as an added hormone. Phytoestrogens, in some ways, act similarly to oestrogen and can reap positive health benefits such as reduced risk of certain diseases. It can also, however, be considered an endocrine disruptor and could potentially have adverse effects on our bodies. First let’s talk about the normal functions and importance of our female hormones.


Oestrogen and progesterone

The two major female hormones are oestrogen and progesterone and are made by our bodies in our ovaries. Oestrogen is an important reproductive hormone which causes changes in the uterus and vagina throughout the menstrual cycle and triggers sexual behaviours. Progesterone is important for preparing the body for a potential pregnancy and works with oestrogen throughout the body. Both are extremely important, in the correct quantities, for healthy sexual development. Our reproductive systems are more vulnerable to changes during our developmental years, such as before birth, in our early years and during puberty. The manipulation of these sex hormones can have a huge effect on our future sexual health if they occur during these sensitive windows. The consumption of phytoestrogens during this time has the most effect.


Let’s consider the positive health impacts of phytoestrogen, this plant-derived compound…


Benefits of phytoestrogens

Everyone is aware that the components of fruit and vegetables are beneficial for our health; phytoestrogens are one of these which contribute to our overall wellbeing and health.

1. Perimenopausal symptoms

It is thought that, due to its close likeness to oestrogen, phytoestrogens have beneficial effects on our reproductive system. It has been suggested that the consumption of phytoestrogens via soy-rich foods helps relieve symptoms of the perimenopause such as hot flushes and night sweats. During this time, the body stops producing oestrogen and so the presence of phytoestrogens may contribute to alleviating the effects that come with this, in a way, allowing the menopause to approach more calmly.

2. Bone density

Phytoestrogens may have preventative or therapeutic actions towards decreased bone density, which also occurs with increased age and around the menopause. Oestrogen itself helps to maintain normal bone density in normal conditions and so its suggested that phytoestrogens have similar properties. These beneficial effects towards bone density in turn reduce the risk of osteoporosis and bone degradation.

3. Cardiovascular health

Phytoestrogens may improve cholesterol levels; they have been found to reduce cholesterol to a small degree in hypercholesterolemic women by increasing consumption of soy protein. Elevated cholesterol levels develop fatty deposits which can increase the risk of heart disease and other cardiovascular problems such as atherosclerosis. By lowering cholesterol levels to a normal and healthy amount, phytoestrogens may help to prevent, or reduce the risk of occurrence of cardiovascular diseases. Those who are at risk of heart disease could consider swapping out a portion of meat for a soy-containing product once a week such as tofu or soy protein alternatives to meat.

The benefits of phytoestrogens seem to be evident in groups of increased risks or abnormal conditions, such as increased risk of heart disease, elevated cholesterol levels, increased occurrence and persistence of perimenopausal symptoms and increased risk of osteoporosis and bone density loss. As a healthy individual who eats a balanced and varied diet, including more soy-rich or phytoestrogen-containing foods could be a good idea, but don’t be disappointed when you don’t see any noticeable effects!


Phytoestrogens as endocrine disruptors

Phytoestrogens are a controversial topic in nutrition and all research is suggestive, even the potential benefits. More concern surrounds the adverse effects of phytoestrogen exposure which is also inconclusive but suggestive. This is because phytoestrogens could be considered as endocrine disruptors.

Endocrine disruptors are chemicals which could interfere with our endocrine system by blocking or mimicking hormones, causing adverse effects. These chemicals can be naturally occurring or man-made. With phytoestrogens, they are naturally occurring in plants and are thought to disrupt processes involved with oestrogen. As mentioned before, our reproductive systems are extremely sensitive to change and the hormones that drive it and so endocrine disruptors could hugely impact our reproductive health. Let’s consider a few aspects that research suggests phytoestrogens could affect …

1. Breast cancer

As oestrogen has direct roles in breast development, it is no surprise that interreference of this hormone could have adverse effects in this area. Research is unclear whether phytoestrogens have a direct impact on breast cancer occurrence but there is evidence to say that a high intake of progesterone could increase the risk of breast cancer reoccurrence in survivors. Typically, survivors or those at risk of breast cancer should include soy products or other high-phytoestrogen-containing products with caution.

High soy intake in early life and development has been associated with increased breast density later in a life, a risk factor for breast cancer. This suggests that phytoestrogens interfere with the function of oestrogen for breast development during these crucial times. Although these risks sound concerning, women without risk to breast cancer or increased density should include soy products in their balanced diet without significant concern.

2. Reproductive function

It has been found that the consumption of some soy foods can reduce the amount of oestrogen and progesterone that circulates your body naturally. Suppression of our vital reproductive hormones could cause reproductive abnormalities like, for example, uterine bleeding, increased symptoms of premenstrual syndrome or irregular periods. In women who experienced these symptoms over a long period of time, their symptoms improved with the reduced intake of soy products, with some seeing improved fertility. These were specific cases and very much applied on an individual basis so it’s important to remember this when considering to completely rule out soy products from your diet. It’s suggested that women who experience menstrual cycle irregularities or are trying to get pregnant should reduce their intake of soy.



Phytoestrogens may have an effect on behaviour. Oestrogen plays a key role in initiating oestrous behaviour – a part of the menstrual cycle that can increase/decrease libido and prepare the body for sex. It has been suggested that phytoestrogens can affect sex, social, aggressive and anxiety-related behaviours by suppressing naturally occurring oestrogen levels. This research is only suggestive and by no means implies that eating soy-rich foods will cause anxiety or decrease libido, it only means that research is beginning to explore the possibility.


As a whole, phytoestrogens are a controversial topic. It’s easy to get spooked by articles out there suggesting that soy directly causes cancer or that phytoestrogens kill your sex drive. However, there is no research to show this, and although some research suggests at risk groups should be cautious of soy, there are also a myriad of positive benefits we can reap from including moderate phytoestrogen sources in our diet. We don’t need to make conscious efforts to include phytoestrogen in our diet if we are already eating enough fruit and vegetables so don’t stress about including it singly in your meals.

Be conscious of how many soy products you’re eating, especially if you are vegetarian or vegan or in an at-risk group, as this is important for any balanced diet.

Blog post by Beth Mulholland

16 views