Can I get tested for IBS?
First things first: All women over age fifty and African-Americans women over age forty-five should have a colonoscopy to make sure there are no polyps or cancer. No matter what her age, any woman with unexplained rectal bleeding should have a colonoscopy to make sure there are no polyps, cancer or inflammation. Sorry, though, there are no accurate blood tests to make the diagnosis of irritable bowel syndrome. However, new blood tests have been developed to identify markers of substances (biomarkers) in the blood that are associated with irritable bowel syndrome. If there is a high suspicion of IBS and the test panel is positive—the tests have good predictability. Conversely, if there is a low suspicion of IBS and the test panel is negative, again, the test has good reliability. But if IBS is suspected and the test panel is negative, well, you still might have it.
Unfortunately, there are large numbers of people having these tests who could be overlooked and who do have IBS, or who are incorrectly told they have IBS. The blood tests sometimes used for diagnosing IBS include ones that are useful in making the diagnosis of celiac disease and inflammatory bowel disease; people with IBS could be told they have one of these other conditions. Other tests—such as stool cultures; routine blood tests looking for anemia or high white blood cell counts, which could indicate an infection or an inflammatory process; X-rays; or endoscopic tests—are useful in ruling out other conditions. However, for most people under fifty, they’re not usually necessary. Celiac sprue (gluten allergy) (see Chapter 4) can be discounted by doing a blood test called tissue transglutaminase antibody.
If I’m diagnosed with irritable bowel syndrome how do I know that I got the right diagnosis?
You can’t be 100 percent sure. Warning signs that would require other diagnoses to be eliminated with testing are:
Onset of symptoms over age fifty
Rectal bleeding
New anemia
Unexplained weight loss
Worsening of IBS symptoms
Poor appetite
A family history of other diseases that affect the gastrointestinal tract
Vitamin deficiencies
Reassuringly, studies have shown that the diagnosis of IBS does not usually change. After six months to six years after the diagnosis was made, only 2–5 percent of irritable bowel syndrome patients were diagnosed with another GI disease. With long-term follow-up of IBS, on average two years, about 2–18 percent of people developed worse IBS, 30–50 percent of patients had no change in IBS symptoms and 12–38 percent of people had a complete disappearance of their symptoms, for reasons unknown. If your symptoms change, tell your doctor.
Why do women bloat?
A great question that is still only partially understood! Most women do not have excess or an increased amount of gas, even though it might feel that way when you’re squeezing into your favorite pair of jeans. The problem seems to be more that the gas doesn’t move out of the small intestine like it should. And when it’s there, watch out! Women with irritable bowel syndrome or other functional GI disorders feel it more. There is an increased sensitivity toward and awareness of what is happening inside the body.
However, not everyone who feels bloated actually has a larger belly. (In a study from Olmsted County, Minnesota, a quarter of the women studied reported they were bloated, but in actuality, only half of the bloated women had an increased circumference when measured!) Younger women are more likely to bloat than older women. Bloating is more common in the lower abdomen than the upper, unless someone has upper intestinal symptoms (like heartburn), whereby bloating can be anywhere in the abdomen or throughout the abdomen. With recurrent nausea, vomiting and pain (called dyspepsia), bloating is also more common in the upper abdomen. Men, meanwhile, are lucky. They bloat and distend only half as much as women. No wonder their pants fit better!
What about distension? Doesn’t that mean you have more gas?
Again, not necessarily. Sometimes your ab muscles just aren’t working right. The diaphragm comes down, the air and intestinal contents pool and the only way for the belly to go is out. Women can bloat if they get stressed. This may be due to a release of hormones or other substances that cause a change in the movement of the bowel or abdominal wall muscles, or just hypersensitivity. Another overlooked but likely cause of bloating is the bacteria in the bowel. The bacteria that are the normal inhabitants of the bowel are different in women with irritable bowel syndrome than those without it—one study shows decreased or absent species of lactobacilli in the intestines of patients with IBS. The fruits that are least likely to cause gas are white grapes, strawberries, blackberries, raspberries, pineapples and oranges. Fruits that are more likely to cause gas are prunes, pears, sweet cherries, peaches and apples. The bacteria in our guts break down the food products that get to the colon and can release rotten gas or compounds, like fatty acids, that could cause bloating.
What causes gas?
There’s no getting around it: Gas is often a by-product of what we eat. We share our body with bacteria; in fact, there are ten to one hundred times more bacteria than cells in our body. These bacteria also inhabit our bowels. When the carbohydrates and fat within our food aren’t broken down by the substances (enzymes) our bodies make and are not absorbed by the intestines into our bodies, the bacteria metabolize them and form gas as a by-product. For instance, if someone is missing the enzyme in the small intestine to break down lactose (the sugar in milk), she becomes lactose intolerant. The lactose travels down to the colon, and the bacteria break down the lactose and release hydrogen gas as a by-product. Fructose is poorly absorbed into the body unless it is accompanied by the sugar glucose. Therefore some fruits are more likely to cause gas than others. These fruits have less glucose than fructose. There are other poorly absorbed short-chain carbohydrates that will cause gas when broken down by bacteria. These are termed FODMAPs (Fermentable Oligo-, Di and Mono-saccharides and Polyols).
The oligosaccharides consist of fructans (wheat, onions, artichokes) that have long chains of fructose and galactans (legumes, cabbage, brussels sprouts). The disaccharides are lactose- (milk) containing foods. The mono-saccharides are fructose-rich foods (fruits). The polyols include sorbitol (added to low calorie foods). A more extensive list of the foods that may cause gas is found on pages 52–53.
Why do I feel stress—and, consequently, gas—so acutely in my stomach?
Strange as it seems, your gut has a brain. More than 95 percent of serotonin resides in the gut, and serotonin, coincidentally, helps modify mood. It is important for the movement of the gut and is a strong determinant of constipation, diarrhea and pain. But cortisol, the “fight or flight” hormone made in the adrenal gland, also causes increased movement in the gut and may be responsible for some of the increased gas when you’re stressed. People with IBS also have a lower threshold for pain in the gut.
One of the tests done to look at how sensitive one’s bowel is to noxious stimuli is to place a balloon in the rectum and distend it. If a balloon is distended in the rectum of an IBS patient, the tolerated volume of air in the balloon is less than that of a person without IBS. In IBS patients, when the balloon is distended in the rectum (ouch!) or if pain is anticipated, areas of the brain are activated. These can be seen on PET (positron-emission tomography) scans that examine blood flow. However, women’s and men’s brains light up in different places. In women, the limbic and paralimbic areas light up. These are areas that amplify pain. In men, areas that are more concerned with inhibiting pain (prefrontal cortex, insula, dorsal pons) light up. Men, too, experience intense pain; it just registers differently.
Why, oh why, does gas smell so disgusting?
Gas is actually a mixture of different gases. Only a minority cause odor (it’s true!). The culprit for the rotten egg smell exuded by some gaseous odors is hydrogen sulfide. Other compounds like methyl mercaptan and short-chain fatty acids, like skatoles, can also impart a noxious odor to our released gas. Ironically, skatoles