The other gas crisis: Adding vegetables and fiber to the diet

Maria, a 70-year-old woman of Cuban descent, enjoys going out with friends and family to sample the various international cuisines available to her in Miami. She eats daintily but with great pleasure, eagerly sampling many different dishes and desserts around the table. She always, however, skips the salad. "I don't eat salad," she says firmly. She shakes her head and gestures vaguely toward her stomach, her small hand making airy circles over her lap. "Lettuce does not ... agree with me. No, no." Maria is too decorous to say the word, but she's talking about gas. And she's not alone. Millions of Americans complain of bloating and flatulence from time to time. Some of these people may have medical conditions such as a serious food allergy, diverticulosis, irritable bowel syndrome, or celiac disease. But many n particularly older Americans like Maria n have simply come to associate bloating and gas (or flatus) with specific foods like lettuce, beans, broccoli and many others. Yet health experts say that Maria's problem likely stems in part from not eating enough salad n or at least, enough of foods high in fiber such as vegetables, fruits, whole grains and, yes, beans. Because her daily diet is so low in fiber, even a modest salad represents a sudden and significant change that her body hasn't learned how to compensate for. The result: gas. According to Karen Collins, R.D., Nutrition Advisor for the American Institute for Cancer Research, "If Maria were to start increasing her intake of fiber-rich foods in a careful, gradual, and permanent way, it probably wouldn't be long before you'd find her happily making return trips to the salad bar. There are a host of small changes people can make in how they cook, eat and live that will help eliminate side effects like bloating and gas." Most digestion takes place within the small intestine. There, enzymes and bile break down foods n first into carbohydrates, protein and fat, and then into nutrients and other substances that are absorbed into the bloodstream and stored for later use. But our enzymes aren't equipped to break down certain elements of our diet n such as specific sugars found in beans and other fiber-rich plants. The undigested matter passes into the large intestine, where it is set upon by bacteria residing there. These bacteria can and do consume the sugars our bodies can't. In fact, they ferment it, producing a mixture of carbon dioxide, methane and hydrogen n with the occasional telltale hint of hydrogen sulfide n in the process. So why, then, might the same three-bean salad cause trouble for one person, but not another? The roster of digestive enzymes possessed by one individual may simply work more effectively than that possessed by another. Also, the volume of air swallowed, the amount of bacteria living in the gut, how well adapted that bacteria is to fiber in the diet, and how quickly food moves through the colon all determine the amount of fermentation that takes place, and the amount of gas produced. Collins advises people to start slowly, with a bowl of whole grain cereal one morning. Each day thereafter, add a single serving of fruit, or a vegetable, or whole grain bread. In the beginning, concentrate on foods that contain soluble fiber, which is easier to digest: oats, oat bran, apples and carrots. Even though the skin of apples and other fruits contains nutrients, it might be a good idea to peel them, at least at first. "Cooking vegetables and fruits is another way to help your body do its job," says Collins. "In part, cooking does what our digestive enzymes do n it softens the walls of cellulose fiber in plant foods and starts to break down sugars." In the specific case of onions, garlic and cruciferous vegetables (broccoli, cabbage, cauliflower), cooking also helps dissipate the plant's natural volatile oils that may promote gas in some individuals. Even beans don't have to be off limits. One reason many bean and chili recipes call for soaking beans overnight is that doing so helps remove the sugars that are fermented by intestinal bacteria. Of course, Collins says, how these foods are cooked also makes a difference. Foods cooked in oil and butter tend to linger in the gut, and this extra time may contribute to digestive problems. On the other hand, roasting, baking, broiling, poaching and steaming are methods that help break down food without slowing its passage through the colon. "Fermentation is what produces the gas, and the longer food remains in the digestive tract, the more fermentation occurs," she says. "So, as a general rule, anytime you increase fiber intake, you must also increase water intake along with it. This is necessary to facilitate food's transit through the gut." Regular physical activity serves the same purpose, and is a natural way to ensure that food moves through the colon smoothly and evenly, before excess fermentation causes a buildup of gas. Diets high in a variety of plant foods have been linked to lower risk for cancer, heart disease, adult-onset diabetes, and many other chronic diseases. Recent research provides an additional incentive: there is increasing evidence that dietary fiber can play an important role in managing weight and preventing obesity.