You can drink soy milk when you have your period for the following reasons: 1. Women lose certain nutrients during menstruation due to blood loss, such as sugar, protein, amino acids, and trace elements, such as vitamin A, vitamin B, and vitamin E and so on. These lost nutrients are important for women’s health. Therefore, women should increase the intake of nutrients during menstruation. Soybean milk is rich in vegetable protein, essential amino acids and vitamins, which can replenish the nutrients lost by women during menstruation due to blood loss. This is why women can drink soy milk during menstruation. 2. Some women experience indigestion during menstruation, such as nausea, vomiting, diarrhea, constipation and so on. Soybean milk is a coarse food, with the function of promoting digestion and gastrointestinal tract peristalsis, so if women have digestive problems during menstruation, they can properly drink soybean milk to play the purpose of treatment and relief.