There can be several reasons for your GI symptoms with oats. A small number of celiac patients react to the protein called avenin in oats. Another issue can be the high levels of soluble fiber in oats. Soluble fiber can cause gas and bloating in some individuals depending on the amount they are consuming.

Can oatmeal cause gas and bloating?

Whole grains such as wheat and oats contain fiber, raffinose, and starch. All of these are broken down by bacteria in the large intestine, which leads to gas.

Do oats increase bloating?

When it comes to settling your stomach, reducing unwanted gas and keeping everything regular, it's hard to look past rolled oats. Not only are they ultra-cheap, filling and low GI, but rolled oats are also very low in FODMAPs, which means they're unlikely to make you bloated.