Alas, there is as yet no definitive answer to this question. Some studies suggest no change in risk, some show decreased risk (in rats), some show an increased risk. Bottom line, we don't know for sure.
I can say this - the phytoestrogens in soy can be harmful or beneficial depending on the woman and the amount ingested. Soy is one of the top food allergens, although that is rarely publicized. And it can adversely affect thyroid function, which may decrease in Menopausal women anyway. Best advice? If you do ingest soy milk without bloating, cramping or other signs of food sensitivity - keep the amount low. And if your breast cancer risk is high (family history, etc.) then you may want to avoid it altogether. It's good to assess your risk with your gynecologist or nurse practitioner. Remember, that plant phytoestrogens may have the same risk as HRT for some women.
Here's some further info about soy for Menopause symptoms from our blogsite:
Menopause Goddess Blog
For just about a year, my hot flashes, insomnia, and mood alterations were down to a dull roar thanks to my natural progesterone cream. And then I started down the next dip on the Menopause roller coaster.
Early in perimenopause, progesterone levels drop. Later in the transition, estrogen levels decrease as well, causing a resurgence of hot flashes, mood swings, insomnia, vaginal dryness, and more. The progesterone cream that worked initially is no longer enough. We may feel the need for estrogen supplementation. I surely did. Following the rules and guidelines for remedies, I wished to start with the least heavy duty, most "natural" remedy first. Enter natural remedy #1: soy.
Natural Soy – The Good News
I decided to do a little research – here’s what I found. Soy has been touted as a healthy food alternative to almost everything: meat (tempeh, tofu), milk (soy milk), cheese (yep, soy cheese), appetizers (edamame soybeans), snacks (soy crackers and chips.) and so on. Soy is also a phytoestrogen or plant estrogen precursor. Ergo, if you want to have "natural" symptom relief from your hot flashes, insomnia, and the like – eat soy. Still have symptoms? Eat more soy. Don’t like the taste or texture of bean curd? You can ingest soy in the form of pills or capsules. A number of popular products can be found in the health food aisle of your grocery store, such as Estroven. For many women, soy has made the transition much milder.
Needless to say, this sounded like THE ANSWER. (However, in my excitement, I forgot the all important rule that "There Is No Silver Bullet" or single panacea for the menopause maladies.) I started taking a natural soy remedy and switched to soy milk.
And I got worse. My hot flashes increased. I couldn’t sleep. I was REALLY cranky. Add to this bloating, stomach aches, and nasal congestion and you have the makings of a Menopausal Monster. I decided a little MORE research was in order. And here’s what I found:
Soy Vey – The Bad News
While soy is a healthy choice for many people, it makes the list of the top 8 food allergens, along with milk, eggs, peanuts, tree nuts, fish, shellfish, and wheat. (source: Mayo Clinic.com) The FDA now requires that all food be labeled if it contains any of these.
Although it is estimated that only 1% of the population has true allergies to these foods, a large number of the population may be intolerant or sensitive to them. What "intolerance" means is that they can ingest small amounts of these substances with no ill effects, but with larger doses symptoms appear. (Those who have true allergies cannot tolerate even a tiny amount of the reactive food without a serious allergic reaction: difficulty breathing, hives, swelling of face, neck, tongue, or shock).
In a nutshell, many of us are unknowingly sensitive to soy. When we increase our intake of soy, we may develop symptoms consistent with food intolerance such as cramping, diarrhea, bloating, dizziness, nasal congestion, and flushing. If we are soy-sensitive, we may actually find our hot flashes and other Change symptoms increasing, as we stress our body beyond the already overwhelming stressors of menopause. Luckily, those of us with soy intolerance have the option of soy-free herbal preparations that contain phytoestrogens, which we’ll touch on in the next blog.
For those who are not allergic or sensitive to soy, ingesting tofu, soy milk, and soybeans might be a godsend. Beware, however, of taking too many soy pills which contain high levels of soy isoflavones. More is not better. There is concern about interference with thyroid function (which translates to even more symptoms for a menopausal goddess). Monitor yourself and your response along with your trusted health practitioner. (See April 3 and March 28 blog entries for guidelines in "Choosing The Right Menopause Remedy for You.")
So what happened? I stopped the soy. And while my menopause symptoms continued unabated, they decreased slightly while the bloating, stuffy head, and abdominal pains disappeared. (My MD tested me for food intolerances – the only one I was sensitive to was indeed soy.) I tried various other remedies: black cohosh, dong quai, primrose oil. None of them seemed to have any effect (except some flushing and heat sensations with the dong quai.) Yet, I knew women where each of these remedies had worked like magic.
What next? My estrogen levels were subterranean. My thermostat was in the nuclear zone. How was I going to cool off literally and emotionally? The saga continues in the next blog entry where we’ll discuss [ominous drum roll please] HRT, also known as Hormone Replacement Therapy.
(material adapted from our book "The Big M")
Hope this helps. Good luck and keep us posted.
Lynette Sheppard RN Menopause Health Maven
Menopause Goddess Blog