Soy Isoflavones for Hormone Health
- melissarivard
- Jul 19, 2025
- 3 min read
By Melissa Rivard, Registered Clinical Naturopath & Nutritionist
As a registered clinical naturopath and nutritionist, staying up to date with best-evidence practice is both a professional requirement and a personal passion. This year, I’ve taken a deeper dive into women’s health through a comprehensive mentorship with one of the best in our industry: Rhiannon Hardingham at RHR Reproductive Health. The learning has been incredibly valuable, building on five years of focused experience in this area. Each year, my knowledge continues to deepen and expand.
In this blog, I want to share why soy isoflavones are an important nutritional tool to consider, especially for supporting hormone health during perimenopause and menopause.
Why Is There So Much Confusion About Soy?
There’s a heap of conflicting information in the media about soy, especially when it comes to hormones and cancer risk. So let’s break it down.
Whole, minimally processed soy has been well studied and is linked to a variety of health benefits. However, highly processed soy, the kind found in ultra-processed foods with long ingredient lists, does not offer these same benefits and may even be inflammatory for some people.
What Are Soy Isoflavones?
Soy contains naturally occurring plant compounds called isoflavones, particularly genistein and daidzein. These compounds are known as phytoestrogens, meaning they can interact with estrogen receptors in the body.
What’s fascinating is that soy isoflavones can modulate estrogen levels, helping to buffer the effects of both high and low estrogen. That’s why they’re so useful during perimenopause, a time when estrogen levels can swing wildly.
Benefits may include relief from:
PMS and hormonal headaches
Period pain
Vasomotor symptoms like hot flushes
Vaginal dryness
Mood changes
Because estrogen receptors are found throughout the body, research has shown that soy isoflavones may also support:
Cardiovascular health (reducing cholesterol levels)
Bone density
Cognitive function
Metabolic health (improving liver function and insulin regulation)
Soy is a great protein source as well and therefore, can be added to boost your protein intake (an important macronutrient for women's health).
Will Soy Help Everyone?
As with anything in nutrition, individual nuance matters. Not everyone efficiently converts isoflavones into their most active forms (like equol), which can influence the degree of benefit.
Is Soy Safe?
The good news: for most people, whole soy foods are safe and even protective. Research shows that soy may help reduce the risk of estrogen-receptor-positive cancers, rather than increase it, contrary to some outdated myths (see paper below).
Caution: People with soy allergies should avoid it entirely and may wish to explore other phytoestrogens such as flaxseeds.
What Type of Soy Should I Eat?
Choose whole, organic, non-GMO soy foods, such as:
Tofu
Tempeh
Edamame beans
Boiled mature soybeans
Miso
Natto
Soy milk (made from whole soybeans—not soy protein isolate)
Avoid highly processed soy (e.g. soy protein isolates in protein bars or snacks).
How Much Soy Should I Eat?
A great target for general health and hormonal support is around 50 mg of soy isoflavones per day. Your practitioner can help personalise this based on your health profile and needs.
To give you a sense of isoflavone content:
Food (per 100 g) | Isoflavones (mg) |
Boiled soybeans | 65 mg |
Edamame beans | 48.5 mg |
Tempeh | 35–70 mg |
Tofu | 22–34 mg |
Soy milk (whole bean) | 7–10 mg |
👉 Quick math tip: 1 g of soy protein = ~3.5 mg of isoflavones.
Recipes I’m Loving Right Now
Here are a few delicious ways to enjoy soy regularly:
Scrambled Tofu (great for breakfast or lunch) - my go to!
Soy isoflavones can be a valuable ally for hormone balance, especially during the perimenopausal years when estrogen levels are fluctuating and post-menopausal when estrogen is low. If you’re curious to learn more about how to incorporate soy safely and effectively into your diet, speak with a qualified health practitioner for personalised guidance.
NOTE: Soy is safe to use with HRT and may even be complimentary!
Justification:
PMID: 35241506
PMID: 33809928
PMID: 39433088
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