There are many reasons that new vegans (and vegetarians) may experience gas. The standard American diet that most of us were raised on is centered around highly refined and processed items, dairy products, and meats -- none of which contain dietary fiber. It's no wonder there's a proliferation in the marketplace of stool softeners (made of soluble fiber) and laxatives. Fruits, vegetables, whole grains, and legumes are loaded with valuable natural fiber, which is vital for intestinal health and proper elimination. It takes time for our digestive systems to adjust to this drastic change in diet and accommodate the healthful incorporation of more fibrous foods.
Gas can also be caused by not properly chewing foods. Whole grains, fruits, legumes, nuts, seeds, and vegetables need to be thoroughly masticated before they're swalled. Digestion begins in the mouth by thoroughly grinding our food into a paste and mixing it with our saliva. The stomach doesn't have teeth. If fibrous foods are swallowed without first being properly broken down in the mouth, we will have difficulty digesting them, and consequently we'll experience stomach pain, distention, and gas.
Another source of gas is how we eat. If air is taken in during chewing or swallowing, it will form gas in the intestinal tract. Most of us aren't aware that we are taking in air as we eat, but this can happen with something as simple as talking or drinking while eating, eating quickly, taking large mouthfuls of food, or just opening our mouths while we chew. Chewing gum can also unwittingly give rise to taking in air and producing gas.
Using straws or drinking carbonated beverages can cause gas too. Mixing carbonated soda with a whole-foods, plant-based diet is essentially asking for trouble.
Food sensitivities can be the root of many digestive problems, including gas, as can certain health problems that may or may not be directly related to the digestive tract. Irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, commonly cause excessive gas.
When people first move to a plant-based diet, they often consume more high-FODMAP foods. These are foods rich in short-chain carbohydrates that have a tendency to ferment in the digestive tract and cause gas, even in healthy individuals. Being aware of which foods are high in FODMAPs and eating smaller portions of them for a short period of time can help minimize gas until the digestive system adjusts.
There is no single reason that people in general experience gas, and vegans are no different from the rest of the population in this regard. However, when you move to a minimally processed, wholesome vegan diet, you may need a little extra time for your body to acclimate. If you're new to a plant-based diet, patience and awareness about what you're consuming and how you're consuming it will, in most cases, be the key to minimizing digestive woes while transitioning to a healthier way of eating.