Q: Can phytoestrogens help relieve menopause symptoms like hot flashes and night sweats? What about women with breast cancer?
I experienced my first hot flash in front of 120 pharmacy students in a large lecture hall in Pullman, Washington. As I explained 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, leaving me drenched and practically dripping with sweat right in front of the class. Talk about being distracted… and embarrassed!
Can phytoestrogens relieve the discomfort of sudden hot flashes/flushes or the 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 primary reason for this difference is diet. The typical Asian diet contains a lot more soy than most Americans eat. Soy foods and concentrates contain phytoestrogens, which are plant-based substances that can act like estrogen.
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. While only 30-50% of women in North America can turn soy into equol, a much higher percentage of Asian or Hispanic women can do this.
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 estrogen receptors: ER-alpha and ER-beta receptors. Most estrogens and phytoestrogens will bind to ER-alpha estrogen receptors, while other phytoestrogens attach to ER-beta receptors.
Phytoestrogens that bind to ER-alpha receptors can stimulate certain types of breast and endometrial cancers.
In contrast, those binding to ER-beta receptors have a protective effect similar to the estrogen-blocking medicines tamoxifen and raloxifene (Evista®).
There are several reasons why it’s tough to pin down and study the effects of a particular phytoestrogen on your body. One reason is that food sources of phytoestrogens usually contain more than one type. When phytoestrogens bind to different receptors from each other, some of the effects can balance each other out.
Plants can have variable concentrations of phytoestrogens depending on their growing conditions. They also can act differently in your body. Depending on whether you are pre-menopausal and still releasing your own estrogens, or you are post-menopausal, with 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 1 or 2 servings a day of soy foods and try it for 3 months to see if your hot flashes frequency 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 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.
Can eating soy cause breast cancer? If you’re not vegetarian, it’s unlikely that you get enough soy in your diet to increase your risk of breast cancer.
Supplements containing soy concentrate or herbal products like black cohosh marketed for “menopause support,” such as Remifemin®, may increase your breast cancer risk.
Here are 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 soy milk consumption.
- Stick to phytoestrogens that have had their potency tested.
Exact concentrations of certain phytoestrogens differ depending on growing conditions. Still, they 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. Still, you should avoid taking supplements containing concentrated phytoestrogens like soy concentrates or black cohosh until more is known about their long-term effects.
