The most commonly asked questions about menopause, botanicals and cancer.
1. What are phytoestrogens? And should they be avoided in our diets after oestrogen receptor-positive cancer?
Phytoestrogens are a group of substances naturally found in plants that are structurally similar to the oestrogen molecule that is made in our bodies. There are 2 major classes of phytoestrogens: isoflavones and lignans. Other classes are coumestans and stilbenes, but are less abundant in the diet and less well-studied.
The most common form of phytoestrogens are called isoflavones, with the greatest dietary source being soya. Other legumes such as chickpeas and green peas also contain isoflavones but in significantly lower levels. It’s useful to know that several factors can actually affect isoflavone content, such as the location of a crop, the time of harvest, processing, and preparation. For example, boiling soya beans can decrease isoflavone content by more than half.
The second most abundant class of phytoestrogen, lignans, is mainly present in flaxseed, although whole grains, vegetables, and tea are also sources.
Because phytoestrogens have oestrogenic effects in the body, they can be very useful in supporting menopausal symptoms when our natural levels of oestrogen start to decline. There is plenty of research showing their health benefits, from reducing hot flushes to improving bone health.
And concerns about phytoestrogens primarily relate to these oestrogenic effects and how they may affect hormone-sensitive types of cancer, including breast cancer. Although research to date is not conclusive, epidemiologic studies show that people who have been consuming phytoestrogens through their daily diet since childhood have a decreased risk of developing breast cancer, while the studies examining the effects of adult exposure and risk of breast cancer are quite heterogeneous.
Still, experts believe that there is no reason to avoid phytoestrogens in the form of food after breast cancer, if taken in moderate amounts and as part of a balanced diet low in saturated fats and high in fruits and vegetables. However, the intake of phytoestrogens in the form of a supplement is not recommended after breast cancer. Please also note that most research to date on phytoestrogens and safety after breast cancer has been conducted on soya. For more information, please read on below.
2. Is it safe for me to have soya in my diet following cancer? And what is the difference between soya products and soya extracts or isoflavones?
The relationship between soya consumption and breast cancer has been a subject of considerable research, and findings have evolved over time.
Soya is rich in isoflavones, and early concerns about soya consumption are linked to its oestrogenic effects and how it might impact hormone-sensitive breast cancer. More recent research has provided mixed findings, with some studies suggesting that moderate soya consumption may be associated with a reduced risk of oestrogen receptor-positive breast cancer recurrence and improved survival rates, while other studies have not found significant effects. Moreover, more recent research suggests that soya isoflavones may act differently in the body than oestrogen.
Population studies in Asian countries, where soya consumption is traditionally high, have shown lower breast cancer rates. This has led to hypotheses that the protective effects of soya may be closely linked to its dietary consumption throughout life.
How about soya and hormone receptor-negative breast cancer?
The relationship between soya consumption and hormone receptor-negative breast cancer is less clear and has been less extensively studied. However, some studies suggest that soya may not have the same protective effects in hormone receptor-negative breast cancer as observed in hormone receptor-positive cases.
How about soya and HER2-positive breast cancer?
The relationship between soya and HER2-positive breast cancer is not as well-studied as the relationship with hormone receptor-positive breast cancer. In one study of Korean women, dietary soya intake was associated with a decreased rate of recurrence in HER-2 negative cancer, but an increased rate of recurrence in women whose tumours were HER-2 positive. However, the evidence is limited and not consistent to date, and more research is needed to draw conclusions.
In summary, research shows that eating whole soya foods is unlikely to increase your risk of getting breast cancer, and if you had breast cancer, eating soya foods is unlikely to increase your risk for recurrence.
Experts emphasise that if individuals choose to include soya in their diet after breast cancer, it should be in moderation and in the form of whole foods as opposed to concentrated and highly processed forms such as in the form of a supplement. Wholefood forms of soya include tofu, edamame, and soya milk, which provide a range of nutrients and fibre that have additional health benefits. It is believed that fermented whole food forms of soya – such as Tempeh, Natto and Miso - are even better, as fermentation increases bioavailability and provides probiotic properties. Remember to opt for organic non-GMO soy.
Please also note that individual responses to soya and phytoestrogens in general can vary, and factors such as age, type of breast cancer, hormonal receptor status, diet, gut microbiota profile, and overall health should be considered. Some women may tolerate soya well, while others may choose to limit their intake.
3. Is it safe to add flaxseeds to my diet after breast cancer?
Flaxseed, also known as linseed, is the richest source of the second most abundant class of phytoestrogens, called lignans.
A clinical trial has shown that 25 g per day of dietary flaxseed has the potential to reduce tumour growth in postmenopausal breast cancer patients. However, the research on flaxseed in breast cancer is still limited. The general recommendation seems to be that moderate amounts of ground flaxseeds (up to two tablespoons per day at most) through diet, in the form of wholefoods, are considered safe.
Flaxseed is also a rich source of Omega-3 in the form of alpha-linolenic acid (ALA) and fibre, providing additional health benefits in regards to cardiovascular and gut health.
4. Is it safe for me to use turmeric in my cooking following breast cancer?
Turmeric's main active component - curcumin - has been shown to have several properties including anti-inflammatory, metabolic-regulating, immune-modulating, mood-enhancing and even anti-cancer benefits.
Using turmeric as a spice in cooking is generally considered safe after breast cancer, when incorporated into a balanced diet. Cooking with turmeric adds flavour to dishes without necessarily providing high concentrations of curcumin.
Remember that curcumin is usually poorly absorbed, and that addition of black pepper and fat to a dish, increases its bioavailability.
In regards to safety of turmeric in the form of a supplement, which typically contains higher concentrations of curcumin than those found in food, concerns are mainly linked to breast cancer patients who are undergoing treatment, particularly chemotherapy and tamoxifen. For instance, research has shown that taking curcumin alongside tamoxifen could reduce drug concentration below the threshold for efficacy, in potentially 20–40% of patients. It should be acknowledged however that this study used very high concentrations of curcumin, and significantly higher than those seen in supplements. In regards to turmeric and chemotherapy drugs, the data so far is inconclusive. Some studies show a potential negative interaction while others actually suggest that curcumin can increase effectiveness of chemotherapy by reducing toxic effects. Nonetheless, the current evidence has been mainly obtained from breast cancer preclinical models, therefore the clinical significance is not yet known. At this stage, if undergoing cancer treatment for breast cancer it is advisable to check with your healthcare provider before taking turmeric in the form of a supplement.
Research shows that eating whole soya foods is unlikely to increase your risk of getting breast cancer, and if you had breast cancer, eating soya foods is unlikely to increase your risk for recurrence.
5. What common botanicals in menopause supplements contain phytoestrogens and should I avoid them following cancer?
Botanicals commonly used to relieve menopausal symptoms that have significant levels of phytoestrogens include soya, red clover, sage, hops, and black cohosh. Experts generally recommend that women with a history of oestrogen receptor-positive breast cancer should avoid supplements containing phytoestrogens, particularly in highly concentrated forms.
However, research does support the safety, and even a potential protective effect, of phytoestrogens in the form of wholefoods.
A whole body and mind approach to menopause.
Regardless of our journey into menopause, we believe that the best route through is to address the whole body and mind. From mindset to nutrition, from rethinking how we secure sleep to rethinking how we move, we may find we need to add new elements to our toolkit to feel well.
The role of naturopathy in your menopause journey.
Naturopathy has a truly holistic view of health, offering a 360 view to nourish and balance our bodies and minds. It relies on science-backed tools such as nutrition, botanicals/herbal medicine, and lifestyle modifications, which can (and should) be implemented alongside conventional medicine. It may also explore additional evidence-based complementary practices such as CBT, EFT, yoga and acupuncture.