You can eat black beans once in a while during menstruation, but not every day during menstruation. Because black beans contain a small amount of phytoestrogens, if eaten every day during menstruation, it will increase the estrogen in the body and cause the endometrium to repair as early as possible. This will reduce the amount of menstruation and shorten the duration of menstruation. Therefore, taking it once in a while during menstruation will not have any effect, but if you take it every day, it will have an impact on the volume and duration of menstruation. It is also recommended not to eat cold food, soy milk, honey, royal jelly, etc. during menstruation, as these foods may cause a decrease in menstrual flow, so special attention should be paid.