Grapes can cause gas. According to Bottom Line Publications, green, red and black grapes are all known to contribute to stomach upset such as diarrhea, nausea and gas if too many are consumed at once.
Grapes contain soluble fiber and fructose. Soluble fiber turns to gel in the body when consumed. According to Jackson Siegelbaum Gastroenterology, the gel created by soluble fiber is broken down by certain types of bacteria in the colon, which creates gas. As noted by WebMD, the fructose found in grapes can cause gas when it is fermented by bacteria in the colon and not properly absorbed in the small intestine.