Q: Can phytoestrogens help relieve menopausal symptoms like hot flashes and night sweats? What about women with breast cancer?
I experienced my first hot flash standing in front of 120 pharmacy students in a large lecture hall in Pullman, Washington. As I was explaining how a particular weight loss medicine worked I felt the temperature in the room skyrocket and my scalp turning hot and prickly. Suddenly, sweat began shooting out of my pores all at once, leaving me drenched and practically dripping with sweat right in front of the class. Talk about being distracted… and embarrassed!
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, and called it the “Japanese Effect”. They suspect the major reason for this difference is diet because a typical Asian diet contains a lot more soy than a typical American diet, and soy foods and concentrates contain phytoestrogens: plant-based substances that can act just like estrogen in your body.
But it may not be just diet alone. Protection against hot flushes might depend upon how well you convert the phytoestrogens found in soy into an even more active form called equol. It’s estimated that only about 30-50% of women in North America can make the conversion to equol, while women of Asian or Hispanic descent are much more likely to be able to do it.
Phytoestrogens act by attaching or binding to the same places in your body that other estrogens do. These binding sites are called estrogen receptors, or ERs. There are two main types of ERs: ER alpha and ER beta receptors. Most estrogens and phytoestrogens bind to ER alpha receptors, which can stimulate certain types of breast and endometrial cancers.
Some phytoestrogens bind to ER beta receptors which creates the opposite effect as ER alpha receptors, instead, these phytoestrogens block the action of estrogen on breast tissue, much like the estrogen-blocking medicines tamoxifen and raloxifene (Evista®), which may help prevent certain types of breast cancer.
There are several reasons why it’s very hard to pin down and study the effects of a particular phytoestrogen on your body. One reason is that common food sources of phytoestrogens often contain more than one phytoestrogen, and these can bind to either ER alpha or ER beta receptors, with opposite effects.
Plants can have different concentrations of certain phytoestrogens depending on their growing conditions, and can act differently in your body depending on if you are pre-menopausal and still making your own estrogens, or you are post- menopausal and have very little estrogen in your body.
How much soy do you need to help hot flash/hot flush symptoms? Most clinical studies use from 40 and 80 mg daily of phytoestrogens from soy-based products. Recent evidence suggests that you should start with 2 servings a day of soy foods and try that for 3 months to see if your frequency of hot flashes decreases.
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 soy milk. Flaxseed, chickpeas, beans, peas, green leafy vegetables, cauliflower and nuts are also 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.
Can eating soy cause breast cancer? If you’re not a strict vegetarian, it’s unlikely that you get enough soy in your diet to increase your risk of breast cancer unless you also take supplements containing soy concentrate or herbal products like black cohosh marketed for “menopause support”, such as Remifemin®.
Here’s 3 Tips on Taking Phytoestrogens Safely:
- 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 consumption of soy milk.
- Stick to phytoestrogens that have had their potency tested.
Exact concentrations of certain phytoestrogens differ depending on growing conditions, but can be standardized with quality control assays of each batch.
- 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 totally avoid soy-based food, but you should avoid taking supplements containing concentrated phytoestrogens like soy concentrates or black cohosh until more is known about their long-term effects.
