Many soy-based beverages contain an array of nutrients including protein, carbohydrates, potassium, B vitamins, iron, phosphorus and trace amounts of sodium and magnesium. Many are also fortified with nutrients, most commonly vitamin A, calcium and vitamin D, while some also have added riboflavin, zinc and vitamin B12. Soy contains fairly high levels of phytochemicals including isoflavones and phytosterols.