The relationship between diet and irritable bowel syndrome symptoms is a topic commonly raised by people being evaluated for IBS. Many patients wonder whether their diet is causing or contributing to their IBS symptoms, and still others worry that their symptoms represent a food allergy. A clinical research study published several years ago found that nearly 80 percent of people who had IBS believed that dietary factors played a role in their symptoms.
The complex relationship between diet and IBS can be broken down into four common questions that people ask their physicians. First, Can eating specific foods make me develop IBS? Second, Can my body’s response to certain foods mimic IBS symptoms? Third, Can specific foods make my IBS symptoms worse? And fourth, Do my IBS symptoms represent a food allergy? In this chapter, I address each of these questions and discuss some common food intolerances.
No (this is the easiest question about diet and IBS for physicians to answer). The etiology (cause) of IBS is not completely known, and, as discussed in Chapter 3, there are several different reasons why some people develop IBS. Although many physicians believe that people can be genetically predisposed to developing IBS, they also recognize that there are contributing factors, such as surgery, an inflammatory process, an infectious illness, medications, or significant stress. It seems reasonable that diet could be one of these contributing factors, but there are no data available to show that a specific food causes IBS to develop. That is not to say, however, that dietary factors can’t contribute or worsen IBS symptoms.
Yes. The key word here is “mimic.” Patients with lactose intolerance, fructose intolerance, celiac disease, gluten sensitivity, or a diet rich in foods that ferment excessively in the colon may experience symptoms that seem typical of IBS (bloating, excess gas, distention, abdominal discomfort, and diarrhea). If a specific food produces symptoms that mimic IBS, then removal of that food from a person’s diet will normally resolve all symptoms. Unfortunately, this rarely happens. What is more common is that a food may contribute to IBS symptoms, but when that specific food is removed from the diet, typical IBS symptoms continue, albeit at a lower level. Here are the common food groups that many people who have IBS are intolerant to:
• Lactose (dairy products)
• Fructose (fruit juices, regular sodas, sports drinks with high-fructose corn syrup, fresh fruits)
• Fructans (onions, peppers, asparagus)
• Galactans (complex carbohydrates found in dried and canned beans)
• Cruciferous vegetables (broccoli, cauliflower, cabbage)
• Gluten (the protein found in bread that gives it a chewy consistency)
In the past, physicians would have rapidly dismissed this question with a quick “no.” However, research during the past decade has shown that some foods may contribute (but not cause) IBS symptoms. The relationship between certain foods and IBS symptoms is difficult to define for a number of reasons. One, for the majority of people who have IBS, symptoms wax and wane over time. Symptoms that fluctuate on a day-to-day basis make it difficult to determine whether a single food item is the actual cause. I commonly hear from patients how one specific food seems to cause them problems one day (more bloating, more gas, more diarrhea) but is then well tolerated on other days. This lack of consistency makes it difficult to determine whether a relationship exists between eating certain foods and developing symptoms of IBS. Two, because some foods and beverages may make symptoms of IBS worse, it is often difficult to measure a response when more, or less, of the food is ingested. Thus it is difficult to determine, on a daily basis, the contribution of that specific food to IBS symptoms. Three, people respond differently to different dietary changes. One patient may have great success with a certain diet, whereas another person has no improvement at all. This should not be surprising, because individuals who have IBS are all different from each other in some way. Even if they have similar symptoms, the cause of the symptoms may be quite different. People who have IBS can’t be grouped together and treated in an identical manner. In other words, although the underlying mechanisms of IBS are the same (abnormal gut motility, visceral hypersensitivity, heightened brain-gut interactions), symptoms are expressed differently in different patients.
People who have symptoms of IBS often wonder whether their symptoms represent a food allergy. Although IBS symptoms may be caused by food allergies, food sensitivities, or an intolerance to certain foods, this is a controversial topic with a large amount of misinformation and misperception. Let me first define a few key terms.
People who have IBS and develop gastrointestinal symptoms (bloating, gassiness, abdominal discomfort, and diarrhea) after eating a specific food may be intolerant to that food. The concept of food intolerance is simple: some people develop symptoms after ingesting a specific food. The underlying cause of this intolerance may be known in some cases (i.e., lactose intolerance and fructose intolerance—see below) but not in others, although some physicians think that intolerance is an example of normal GI physiology that is just highly exaggerated. Others think that symptoms of food intolerance are yet another example of how the gut is hypersensitive in people who have IBS. Another theory is that these symptoms may represent a mild food allergy.
Some people seem to be overly sensitive to different foods. Symptoms of food sensitivity are similar to that of food intolerance, but milder. One example of a food sensitivity is a sensitivity to fat products. Many people, regardless of whether they have IBS, find that they are a little queasy or nauseated after eating a rich, fatty meal. These symptoms may develop because fats slow the normal emptying of the stomach, which can then lead to acid reflux. In addition, the slow emptying of the stomach may make symptoms of bloating and gassiness worse. Other people who are sensitive to fatty foods may develop diarrhea after eating a richer than normal meal. Patients with these symptoms are not allergic to fats and generally can tolerate some amount of fat in their diet; they are just more sensitive to fats than other people. Overall, the area of food sensitivity remains somewhat vague and ill-defined, and the mechanisms that underlie it are still not completely understood.
Whereas some people may be sensitive to or intolerant of certain foods, others develop severe symptoms after eating a specific food. These symptoms may include severe abdominal pain or diarrhea, shortness of breath, development of a rash, or swelling of the mouth, tongue, or throat. Patients with these symptoms are most likely allergic to a certain food. One study has shown that 30 percent to 50 percent of individuals who have symptoms of IBS believe that they are allergic to certain foods. However, when tested, only 1 to 5 percent of patients who have IBS are truly allergic to a specific food. This is no different from the general population, where 1 to 3 percent of people are truly food allergic. Food allergies are more common in people who have other “classic” allergic diseases, such as asthma, allergic rhinitis, and atopic dermatitis.
A true food allergy is a very specific, immunologically mediated event. The body reacts as though something foreign has been introduced into the body—more specifically, into the GI tract. The body then mounts an immune response and attacks the foreign substance using immunoglobulins released from lymphocytes. Other cells (mast cells) participate as well, and these cells are important in the development of the allergic reaction. During this process, significant inflammation develops throughout the body, including the oropharynx (itching in the mouth or lips; swelling of the tongue, palate, and throat), skin (hives or a rash), pulmonary system (coughing, wheezing, shortness of breath), and the GI tract, which can lead to a variety of symptoms, including abdominal pain, bloating, and diarrhea. True food allergies generally develop within minutes of exposure. Patients with these symptoms should be evaluated by an allergist to identify the specific foods that precipitate such a violent and potentially dangerous reaction. Allergists frequently perform a skin test to identify the specific food that a patient is allergic to, although this is not a perfect test. Patients who have true food allergies are treated with strict dietary avoidance and occasionally with medications. In addition, these patients should always have an emergency epinephrine injection close by (also called an epinephrine pen, or EpiPen). The most common food allergies are shown in Table 10.1.
Overall, the most common adverse reaction to food occurs with the ingestion of lactose. Using the terms defined above, this is not an allergic reaction but an intolerance. Lactose is the major sugar found in milk products. It is categorized as a disaccharide (di means “two”), since it is made up of two different simple sugars, glucose and galactose. After being ingested, lactose is normally broken down by lactase, an enzyme found in the small intestine. When the milk sugar is not completely digested, the unabsorbed sugar travels through the small intestine and colon. Along the way, the undigested lactose pulls water with it, eventually making the stool looser. In addition, bacteria in the colon ferment the undigested lactose, producing symptoms of gas, bloating, and diarrhea. The lactase enzyme is found in high levels in newborns and during childhood. This makes sense from an evolutionary point of view, since milk is a vital part of the diet after birth and during early childhood. However, milk becomes a less important part of our diet as we age, since we can obtain calories, protein, and other nutrients from a variety of other foodstuffs. Many people notice that as they get older, they are less able to digest milk and other milk products (cheese, yogurt, ice cream) as well as they did when they were children. This change in digestion occurs because the ability to produce the enzyme (lactase) that breaks down milk sugar (lactose) slowly decreases over time. Some people may lose all or almost all of their ability to produce the lactase enzyme and thus become completely lactose intolerant. Others lose only a small proportion of their lactase-producing capability and thus are better able to tolerate larger portions of milk products. For most people, lactose intolerance is not an all-or-none phenomenon but rather one of degrees.
Table 10.1. Common Food Allergies
Peanuts Tree nuts (hazelnuts, walnuts, pistachios, pecans, pine nuts) |
Eggs Cow’s milk Soy Fish |
Shellfish Soybeans Wheat |
Overall, approximately 30 to 35 percent of adult Americans are lactose intolerant at some level. In certain populations (African Americans, Asian Americans), the prevalence of lactose intolerance may be as high as 75 percent. Contrary to popular opinion, lactose intolerance is not more common in people who have IBS compared to the general public. (See Chapter 15 for more information on how to diagnose and treat lactose intolerance.)
Although lactose is the milk sugar most commonly blamed for aggravating the symptoms of IBS, other sugars may also cause problems in individuals who have IBS. Fructose is the best example. Fructose is a simple sugar (called a monosaccharide) and is commonly added to many foods as a sweetener. Most carbonated beverages, fruit drinks, and energy or sports drinks contain high-fructose corn syrup. A 12-ounce soda typically contains 20 to 30 grams of fructose. Fructose is also present in fruits, berries, peas, onions, and artichokes. Like lactose, some people are fructose intolerant. Symptoms are similar (bloating, gas, loose stools, stomach churning and gurgling) and, as with lactose, people often have a threshold for the amount of fructose they can ingest. One or two soft drinks may be fine during the course of a day, but a large glass of fruit juice at breakfast, two soft drinks at lunch, a sports drink after going to the gym in the afternoon, and one or two sodas in the evening may be just too much for the body to handle. One study of patients who had functional bowel symptoms found that 30 percent developed GI symptoms (gas, bloating, and diarrhea) and had an abnormal breath test with just 25 grams of fructose, whereas 58 percent developed GI symptoms and had an abnormal breath test with 50 grams of fructose. Overall, the frequency of fructose intolerance may not differ significantly when people who have IBS are compared to the general population, but the intensity of symptoms may differ.
Many clinicians now recommend a gluten-free diet for patients who have IBS. Although easy to recommend, a true gluten-free diet can be difficult to institute, tricky to follow, and add significant costs to an individual’s food budget. Therefore, before adopting a gluten-free diet, you should carefully examine the evidence supporting this diet. To best answer the question of whether a gluten-free diet might improve GI symptoms in people who have IBS, let me first explain what gluten is and review the difference between a true wheat allergy (celiac disease) and gluten sensitivity.
Gluten is a protein found in wheat, barley, and rye. This protein is broken down during the normal digestive process, and the peptides (small pieces of protein) are absorbed. However, in genetically susceptible individuals (those who are human leukocyte antigen [HLA] DQ2 or DQ8 positive), the peptides initiate an immune response mediated by T lymphocytes. A cascade of events then follows, which may include the development of inflammation in the lining of the small intestine, increased permeability of the gut wall, atrophy (wasting away) of the surfaces of the cells that line the small intestine, and consequently the inability to properly absorb necessary nutrients. This is the clinical condition called celiac disease, which represents a true wheat allergy. Celiac disease can be diagnosed using a combination of symptoms, serologic tests (for example, tests for antibodies to tissue transglutaminase [TTG]), and duodenal biopsies. The prevalence of celiac disease in the United States and Canada is estimated at 0.4 to 1 percent (e.g., 4 to 10 people out of 1,000).
Some people who have IBS develop GI symptoms (bloating, gas, distention, and diarrhea) after ingesting products that contain wheat; however, when properly evaluated (e.g., blood tests such as a serum TTG antibody test, a test to look for the necessary genes, or duodenal biopsies at the time of upper endoscopy), they do not meet the criteria for being diagnosed with celiac disease. These patients are considered to have a gluten sensitivity. Although a standardized and precise definition of gluten sensitivity has not been agreed on, a common-sense working definition is that gluten sensitivity is a condition that responds to or improves with the exclusion of gluten from the diet. At present, a favorable response means that dietary avoidance of gluten improves GI symptoms (which vary from person to person). In the future, research studies may show that gluten sensitivity is just one end of a spectrum of gluten-associated disorders.
As noted above, celiac disease is a true food allergy that affects approximately 0.4 to 1 percent of the U.S. population. Celiac disease is not a new disease—it was first described nearly 2,000 years ago, and its presence in children, and their response to a wheat-free diet, was described in the late 1880s by the physician Samuel Gee. In essence, celiac disease is an autoimmune response that occurs in genetically susceptible individuals (they have human leukocyte antigens DQ2 and DQ8). The autoimmune response develops when wheat, barley, or rye (all of which contain gluten) is ingested, creating inflammation in the small intestine, which can cause symptoms of gas, bloating, distention, and diarrhea. In addition, the inflammation can lead to anemia, vitamin deficiencies, osteoporosis, and even nerve injury. It can generally be diagnosed with a blood sample (a serum TTG antibody test) or an upper endoscopy with biopsies of the duodenum. Treatment is avoidance of all grains that contain gluten (wheat, rye, barley). Although this may sound easy, it can be very difficult to avoid all of these food products. Wheat can turn up in all kinds of foods where it does not seem to belong (e.g., salad dressings, cold cuts, ice creams, soy sauce), and it even appears in nonfood items, such as lipstick. When patients are meticulous about avoiding gluten, they generally notice a dramatic improvement in symptoms. Fortunately, more and more stores are now selling gluten-free products, so the diet is much easier to maintain.
Another group of foods that can mimic or worsen symptoms of IBS are high-fiber foods such as fruits, vegetables, and beans, and over-the-counter fiber products. We are all well aware of the health value of fruits and vegetables. They are low in fat (except avocadoes) and contain essential vitamins and minerals (such as beta-carotene and vitamins E and K). Current recommendations are that all adults consume at least 25 to 30 grams of fiber each day. In general, diets that focus on fruits and vegetables (such as a Mediterranean diet) are thought to increase overall health, well-being, and longevity. Fruits and vegetables, due to the presence of insoluble (not completely digestible) fiber, also add bulk to the stool. The presence of fiber causes retention of water in the stool. Water retention generally leads to increased stool volume, increased stool weight, more rapid passage through the large intestine, and increased ease of evacuation with less straining, which can be helpful for people who experience constipation.
One of the problems with insoluble fiber, however, is that it is not completely digested or broken down within the GI tract. The indigestible and incompletely absorbed products then lead to gas formation within the colon, with increased bloating and distention, which can be uncomfortable. For patients who have IBS and constipation, the addition of fruits and vegetables to their diet is often very effective in relieving symptoms of constipation (stool frequency increases and straining decreases). However, the addition of fiber does not improve the abdominal pain of IBS and for many patients, bloating worsens. Of all the vegetables, the cruciferous vegetables (broccoli, cauliflower, cabbage) are the worst offenders with regard to increased gas production and bloating (see Chapter 15 for the low-FODMAP diet).
Other food products that can cause bloating include those that contain sorbitol. Sorbitol is a sugar that is not broken down within the upper gastrointestinal tract. As it passes through the GI tract it is eventually broken down by bacteria in the colon, releasing gas and causing bloating. Sorbitol is commonly used as a sugar substitute and is found in sugar-free candies, gums, and mints. Patients who have significant problems with gas and bloating should review their diet carefully to make sure that they are not taking in sorbitol.
Many other common foods may cause symptoms in people who have IBS, including caffeine, carbonated beverages, onions, and peppers. Caffeine usually does not worsen bloating, but it does act as a stimulant to the GI tract and can increase stool frequency and cause cramps. Some individuals who have IBS and constipation use the side effects of caffeine to their advantage—one or two cups in the morning may help stimulate a bowel movement. Carbonated beverages may cause problems if they are sweetened with high-fructose corn syrup. Additionally, the carbonation bothers some people who have IBS, possibly because the gas bubbles distend or stretch the stomach. Although foods like onions, peppers, chocolate, and other products like alcohol and cigarettes are often blamed by people who have IBS for their symptoms, no research study has ever formally investigated whether these products truly cause worse symptoms in people who have IBS compared to the general population.
A small number of individuals who have severe IBS (frequent symptoms to daily debilitating symptoms) find that they are intolerant to many or nearly all foods. These people may think that they are allergic to almost all foods because everything they eat causes gas, bloating, or abdominal pain or discomfort. However, true food allergies (the most common of which are to peanuts, eggs, and shellfish) occur in only a small percentage of people, and documented allergies to multiple foods are very rare. The following case study describes a woman who believed that she was allergic to all but a few foods.
Jean is a 37-year-old woman who was referred to me because of multiple food allergies. During our first appointment, she told me that food had been “an issue all of my life.” She stated that she was allergic to nearly every food and that she currently lived on bottled water, Saltine crackers, lemon pudding, and small amounts of boiled chicken. She had lived that way for several years because “everything” she ate caused bloating, gas, cramps, and abdominal discomfort. She said that sometimes even drinking water caused abdominal pain, gas, and bloating. Jean is 5 feet 7 inches tall. Her physical development and growth were normal during her early childhood and teenage years, and in college her weight ranged from 120 to 145 pounds. She worked in a bookstore after graduating from college and had three children over the next several years. The first two children were healthy; however, the third child was colicky, developed some feeding problems, became very sick during the first few months of life, and after several months in and out of the hospital, died. Jean stayed at home after that and did not return to work. Her weight dropped to 98 pounds and then stabilized at 102 to 103 pounds.
During the decade before I saw Jean, she had tried a variety of diets to improve her symptoms, including low-fat, low-protein, low-carbohydrate, high-carbohydrate, liquid-only, protein-only, all-citrus, Atkins, Mediterranean, and the cabbage soup diet. Symptoms of bloating and abdominal discomfort with altered bowel habits plagued her during all of these diets. She had seen seven or eight gastroenterologists, in addition to two internists, two dieticians, a surgeon, and three allergists. Her weight had been steady at 103 pounds for several years. She had undergone extensive testing, including blood work, several upper endosco-pies, abdominal x-rays, CT scans, two colonoscopies, and an x-ray study of her small intestine. All of these tests were normal. A test to measure stomach emptying was also normal, as was a CT scan of her chest and head. Blood work performed several times to look for celiac disease (and duodenal biopsies) were normal. She did not have asthma, seasonal allergies, or atopic dermatitis. Skin testing and specialized blood work to look for allergies were all normal.
In terms of treatment, Jean saw a chiropractor for several sessions but did not experience any relief of her symptoms. She also tried acupuncture without success. Other unsuccessful treatment plans were prescribed by one doctor who treated her with antibiotics for presumed bacterial overgrowth (an uncommon condition in which the small intestine is overpopulated with bacteria) and by a different physician who treated her with several courses of medications for candidiasis (Candida is a common yeast). Jean had been scheduled to see a psychiatrist on two different occasions but cancelled those appointments because she didn’t want to leave the house. After reviewing her family history, I saw that her family members were all well and that there was no history of food allergies in the family. Jean was somewhat anxious during the interview. She said that she could not get out anymore. Her husband did all of the shopping and ran all of the errands. Except for doctors’ visits, she did not leave the house. Her physical examination was normal, except that she was extremely thin. Simple laboratory tests performed on the day of our office visit (blood count, electrolytes, kidney function tests, sedimentation rate, thyroid tests, and liver tests) were all normal.
I had a long discussion with Jean and explained that, although some people can be allergic to some foods, it is rare to be allergic to multiple foods and nearly impossible to be allergic to all foods. Jean’s symptoms of bloating, gassiness, and abdominal discomfort after eating a meal were all consistent with IBS. In addition, I explained that her anxiety was probably playing a role in her symptoms and that she had symptoms of agoraphobia (from the Greek—literally, fear of the marketplace—or in more modern terms, fear of leaving the home). I explained that, after eating a severely restricted diet of water, crackers, and chicken for several years, it would take some time for her body to get used to new foods in her diet.
In terms of a treatment plan, I suggested that she gradually introduce new foods into her diet while at the same time initiate treatment for her fear of going out in public and for her anxiety. Jean started taking a daily multivitamin with iron and I prescribed a very low dose of a selective serotonin reuptake inhibitor (SSRI). SSRIs are used to treat a variety of medical problems, including depression, anxiety, obsessive-compulsive disorders, and phobias. Together, we wrote out a schedule so that she would slowly increase the dose of the SSRI every 3 weeks. She was cautioned that she might not notice any improvement in her anxiety or her fear of going out for two to three months. We also discussed her diet at length and wrote out a careful schedule whereby she would introduce a new food into her diet every seven days. I asked Jean to take note of her symptoms during the introduction of the new foods but not to stop them unless severe symptoms developed (such as severe nausea, vomiting, diarrhea). Jean started by adding small amounts of chicken broth during the first week, white rice during the second week, grits and rice cereal during the third week, and egg whites during the fourth week. I asked her to avoid adding wheat products and high fiber foods during the first month. Jean reported back to me via brief phone calls each week, stating that with the introduction of each new food at the start of the week her symptoms were “terrible,” although she acknowledged by the end of the week that her symptoms probably weren’t that different from her baseline symptoms. At the end of the month, she had gained nearly one pound and (although cautious) seemed somewhat optimistic. During the next several months, with my guidance via frequent office visits and phone calls, she gradually introduced a new food into her diet each week and continued to increase the dose of her SSRI. By the end of the sixth month, she had gained five pounds, had more energy, and felt less anxious. She returned to the care of her local gastroenterologist and internist and over the next 2 years, with careful guidance, frequent visits, and continuation of her medication, she gained another 10 pounds and felt significantly better. She still feels bloating and abdominal discomfort with many foods; however, she now acknowledges that “that’s just who I am” and she doesn’t eliminate a food from her diet every time she has a brief episode of discomfort or bloatedness.
When I first saw Jean, she was essentially already on an elimination diet. Some physicians use an elimination diet to try to sort out the tricky issues of food intolerances, food sensitivities, food allergies, and symptoms of IBS. A strict elimination diet begins by removing virtually all foods from the diet while only ingesting very simple foods that are generally considered well tolerated by all. An example would be to consume only water, white rice, and boiled chicken to start. Then, during the course of weeks to months, different foods are slowly added to the diet, while symptoms are carefully monitored.
Alternatively, some physicians use exclusion diets when they evaluate an individual with suspected food allergies. Exclusion diets start by excluding foods commonly believed to cause GI distress in many people; these foods may include wheat products, coffee, cereals, and dairy products. After two weeks of being on this diet, if no symptoms improve, then it is unlikely that diet plays a role, and practitioners typically instruct patients to return to their original diet. If symptoms improve to some degree, then patients are asked to slowly reintroduce foods, one at a time, to determine whether a food truly causes symptoms. If a symptom recurs, then that food should be eliminated again. Ideally, after waiting several days, the patient should reintroduce that same food into the diet again. This process is called challenge/rechallenge. If the exact same symptoms recur, then it is possible that the patient is intolerant to that food. However, since symptoms of IBS do wax and wane, it is not uncommon for the symptoms to not recur during the rechallenge and the patient to not be truly intolerant to the food. Rather, the typical symptoms of IBS were just confused with the ingestion of that food, and the patient mistook those symptoms of IBS as being related to a food allergy. One study evaluated the use of exclusion diets and found that 50 percent of patients felt that they had some improvement in their symptoms. Note that not all patients improved and that even those who did improve did not have resolution of their symptoms. These study results highlight the difficulty of separating the symptoms of IBS from food intolerance.
People who have IBS commonly have some discomfort or problems after eating specific foods. When visiting a doctor, such patients should provide a thorough history of their symptoms so that physicians can help determine what food, if any, is the cause. Using a symptom diary can be helpful for many people. Although true food allergies are uncommon, people who have severe symptoms should visit an allergist or immunolo-gist for a thorough evaluation. It is important to differentiate the symptoms of food intolerance from the symptoms of IBS—without doing so, individuals may start to avoid all foods.
• Eating specific foods will not cause you to develop IBS.
• People who have lactose intolerance, fructose intolerance, celiac disease, gluten intolerance, or a diet rich in foods that ferment excessively in the colon may experience symptoms that seem typical of IBS.
• Individuals who have IBS and develop gastrointestinal symptoms after eating a specific food may be intolerant to that food. If the symptoms are mild, the person may be considered sensitive to that type of food. If the symptoms are severe, the person is most likely allergic to that type of food.
• Lactose is the food substance most likely to cause problems in the GI tract. Nearly 30 to 35 percent of adult Americans are lactose intolerant to some degree. Typical symptoms of lactose intolerance include bloating, gassiness, abdominal distention, and diarrhea.
• Fructose is another sugar that is often difficult to break down in the GI tract. Typical symptoms of fructose intolerance are similar to those of lactose intolerance.
• Gluten sensitivity is when people develop GI symptoms after they ingest products that contain gluten, such as wheat. It is not a true food allergy like celiac disease.
• Celiac disease is a true food allergy (an immune response) that develops due to gluten proteins. It is present in approximately 0.4 to 1 percent of Americans. Treatment consists of avoiding all products that contain gluten.
• Fiber adds bulk to the stool and accelerates transit of stool through the GI tract. However, too much fiber can worsen symptoms of bloating and gas and can even cause diarrhea.
• Sorbitol is often used to sweeten foods and liquids. Since it is not broken down in the upper GI tract, sorbitol may cause gas and bloating when it reaches the colon.
• Some physicians use elimination or exclusion diets to evaluate a patient with suspected food intolerances, sensitivities, or allergies. These diets can be difficult to maintain, and they require time and patience.