Excessive soy intake can cause gas in some people. Like beans, soy products are derived from a legume. Some people have a hard time digesting the sugars in legumes which results in gas when eaten in large amounts. If you feel that soy is causing the problem, swap it for other proteins (e.g., quinoa, nuts, eggs, or milk and yogurt) and see if you notice a difference. If gas is still a problem, talk with your doctor about it. To see how much protein is in popular vegetables, check out our quick nutrition charts.