Do soyfoods help or hurt breast cancer patients? That question has been hotly debated over the past 20 years. Although older animal studies raised some initial concerns, extensive human research not only suggests soyfoods are safe for women with breast cancer but potentially beneficial. Population studies show that consuming 1-2 servings of soyfoods per day after a diagnosis of breast cancer reduces recurrence and improves survival. Now, research published in Breast Cancer Research and Treatment that was conducted by investigators from several US universities suggests that breast cancer patients who consume soyfoods are less likely to suffer from menopausal symptoms and fatigue.
Women involved in this study were recruited from two California cancer registries. All women had completed primary treatment for breast cancer. In total, there were 192 Chinese-Americans and 173 Non-Hispanic Whites. Information on dietary intake and symptoms was obtained through a 1-hour-long survey administered via telephone. The dietary questionnaire included four questions specifically about soyfoods. Women were divided into three soyfood intake groups: none, low and high intake.
In addition to obtaining information on dietary intake, all women in the study were asked if they experienced any of 34 possible treatment-related symptoms and its severity within the past 12 months prior to the interview date. Symptoms were assessed using a five-level scale, from “not at all” to “very much.”
When all women were included in the analysis, the findings showed that high-soy-consuming patients were less than half as likely to report having menopausal symptoms in comparison to women who didn’t consume soyfoods. Symptoms included hot flashes or night/cold sweats, vaginal dryness/pain with intercourse and vaginal discharge. Similarly, high-soy-consumers were also about half as likely to suffer from fatigue.
The experimental design of this study doesn’t allow for definitive conclusions about the benefits of soyfoods to be made. However, given that other research shows that soyfoods may improve the prognosis of breast cancer patients and that soyfoods are excellent sources of protein and healthy fat, adding soyfoods to the diet makes sense for women with breast cancer. The results of the current study suggest that about two servings per day are sufficient to derive benefit. One serving is a cup of soymilk, one-half cup of tofu or edamame, or one ounce of soynuts.