Can phytoestrogens relieve common menopausal symptoms like hot flashes and night sweats?

Q: Can phytoestrogens relieve common menopausal symptoms like hot flashes and night sweats? What about women with breast cancer?
I experienced my first hot flush one March afternoon in Pullman, Washington. Standing in front of 120 pharmacy students, I was explaining how a particular weight loss medicine worked when suddenly I felt my temperature spike and my scalp get hot and prickly. A few seconds later, sweat gushed out of my neck and back, soaking my white oxford shirt. Yikes!
Chilled and shivering, I looked over at the clock and announced to the class, “Let’s take a 10-minute break, okay?” 
Can phytoestrogens relieve the physical and social discomfort of menopausal symptoms like sudden hot flashes/flushes or their night-time equivalent, night sweats? 
For decades, researchers have noticed how Asian women don’t suffer as much from hot flashes during menopause as Western women do, labeling it the "Japanese Effect." The primary reason for this difference is believed to be diet. 
A typical Asian diet contains a lot more soy than a standard American diet. Foods containing soy and soy concentrates contain phytoestrogens, which are plant-based substances acting similarly to estrogen in your body. 
But eating more soy is only part of the answer. Protection against hot flushes may also depend upon whether your body can change the basic phytoestrogens found in soy into equol, a more powerful phytoestrogen. Overall, 30-50% of North American women can convert soy into equol, with a higher percentage seen in Asian and Hispanic women. 
Phytoestrogens act by attaching or binding to the same places in your body that other types of estrogens do. These binding sites are called estrogen receptors, or ERs. The two main types of ERs are ER alpha and ER beta receptors. Most estrogens and phytoestrogens bind to ER alpha receptors, stimulating specific types of breast and endometrial cancers. 
Some phytoestrogens bind to ER beta receptors instead, creating the opposite effect as ER alpha receptors do. Binding to ER beta receptors BLOCKS the action of estrogen on breast tissue. This is similar to the estrogen-blocking medicines tamoxifen and raloxifene (Evista®) and may help prevent certain types of breast cancer. 
Unfortunately, it’s difficult to study the effects of any particular phytoestrogen on the body. One reason is that food sources of phytoestrogens often contain multiple types of phytoestrogens. These various phytoestrogen compounds may bind to either ER alpha or ER beta receptors, triggering different effects. 
Plants can also have different concentrations of phytoestrogens, depending on their growing conditions. A third reason is how much estrogen is already there. Phytoestrogens in supplements or foods can have a different effect on pre-menopausal women making estrogen compared to post-menopausal women with much less estrogen in their bodies.   
How much soy do you need to reduce hot flash/hot flush symptoms? Most clinical studies have used between 40 and 80 mg daily of phytoestrogens from soy-based products. Recent evidence suggests you should start with 2 servings a day of soy foods for 3 months, noting whether you experience fewer episodes of hot flushes/flashes.
One serving of soy food can be 3 ounces of tofu, ½ cup of edamame, ½ cup tofu, ¼ cup soy nuts, or 1 cup of soymilk. Flaxseed, chickpeas, beans, peas, green leafy vegetables, cauliflower, and nuts are good sources of phytoestrogens. After trying soy for 3 months, if you don’t notice any decrease in your hot flashes or hot flushes, you can stop it.
Could eating soy cause breast cancer? If you're not a vegetarian, it's unlikely that you'd get enough soy in your diet to increase your risk of breast cancer. 
However, the phytoestrogens and estrogen-like compounds in soy concentrates and herbal products like black cohosh marketed for "menopause support," like Remifemin® CAN increase your breast cancer risk.
Here are 3 Tips for Taking Phytoestrogens Safely:
1. You CAN eat food containing soy, even if you have breast cancer. 
Moderation is the key. If you are vegetarian or vegan, don't eat tofu or tempeh every day and control your soy milk consumption. 
2. Be cautious with supplements for menopausal symptoms.
If you have a family history or an increased risk of breast cancer, you don't have to completely abstain from soy-based food. Instead, avoid taking supplements containing concentrated phytoestrogens like soy concentrates or black cohosh until more is known about their long-term effects. 
3. Stick to phytoestrogens that have had their potency tested. 
Exact concentrations of certain phytoestrogens differ depending on growing conditions. The best phytoestrogen supplements measure and standardize each batch to insure consistent potency. 
Dr. Louise Achey, Doctor of Pharmacy, is a 40-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Check out her NEW website for daily tips on how to take your medicine safely. ®2020 Louise Achey


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