Gut myths? Clearing up confusion in the GI tract.
When it comes to your GI tract, it's hard to know what's what. Entire aisles in the drugstore and shelves in the supermarket--not to mention your grandmother--promise answers. Yet misconceptions abound. Here are half a dozen that won't fool you.
An estimated 63 million Americans complain of chronic constipation, 2.2 million have diverticular disease, at least 1.8 million can't tolerate gluten, and many millions would no doubt give up that new iPhone to avoid all future embarrassing episodes of gas. (Okay, maybe not.)
If you've got gut issues, you're not alone. And no one's saying they're easy to solve. But we can at least put some GI myths to rest.
MYTH: Got gas? Beans, vegetables, and milk are the main culprits.
Beans, cabbage, Brussels sprouts, milk, bran. Those are some of the usual suspects when people are trying to figure out why they're experiencing, ahem, gas. And those foods can cause gas.
But most of us overlook a growing source of the problem: inulin, or chicory root extract, one of the most popular ingredients in "high-fiber" foods.
"Of all the fibers added to foods, inulin is the one that probably causes the most intestinal gas," says fiber expert Joanne Slavin, professor of nutrition at the University of Minnesota. "Inulin contains sugars that our digestive enzymes can't break down."
The enzymes do just fine with sugars that have only one or two basic units (called saccharides). Sucrose, or table sugar, for example, is a disaccharide that is broken down in the small intestine into fructose and glucose.
But when it comes to sugars made up of three or more units--often called oligosaccharides--our enzymes are useless. So the sugars end up as food for the bacteria in the gut.
"Inulin is quickly and completely fermented in the large intestine," explains Slavin. And when your bacteria finish fermenting it, you get stuck with the gas they give off.
"Beans are notorious for causing gas because they have sugars like raffinose and stachyose," notes Slavin. Raffinose has three sugar units. Stachyose has four.
"If you look at the literature on treating or cooking beans to make them less gassy, it's mostly to get the oligosaccharides out of there," she adds.
(Beano tablets can prevent gas because they contain an enzyme that breaks down raffinose and stachyose.)
Whether inulin is a problem depends on how much you eat and who you are.
"Our review of studies found that inulin is generally well tolerated at levels up to 15 grams a day," says Slavin. But at around 20 grams, flatulence or bloating is more likely. (1) "So dose is a big issue, and there's also individual variability."
Each serving of Fiber One 90 Calorie Brownies, Fiber One Cottage Cheese, and Yoplait Light with Fiber has five grams of fiber, and much of it is inulin. Some Fiber One Chewy Bars have up to nine grams.
"If you have a serving of beans, you'll get about three grams of oligosaccharides, not nine grams," says Slavin. "And they're more manageable in a real food because they're digested more slowly and usually mixed with other foods."
Another hidden source of gas: sugar alcohols like sorbitol and maltitol.
"They're low-calorie carbohydrates because they're not completely digested and absorbed," explains Slavin. "Typically, if you're eating sugar-free candy or gum, your exposure to sugar alcohols is low, but if people eat the whole bag of candy, it can cause gas."
Sugar alcohols aren't all equal, though. In small studies, some people complain of gas when doses of sorbitol reach 10 to 20 grams, but few complain unless they get at least 30 to 40 grams of maltitol. (1,2)
Most foods don't have that much. Breyers Vanilla or Chocolate CarbSmart and No Sugar Added ice creams, for example, have four to five grams of sorbitol per half cup, but many people start at a whole cup. And Baskin Robbins No Sugar Added Caramel Turtle Truffle ice cream has 25 grams of maltitol per scoop.
Of course, some people may eat more than one food with sugar alcohols during the course of a day. And people vary. "Most people can tolerate normal doses, but not everybody is the same," says Slavin.
On the plus side, sugar alcohols have fewer calories than sugar, and inulin spurs the growth of Bifido bacteria, which may be good for gut health (that's why it's called a "prebiotic"). But the more bacteria in your gut, the more gas they give off.
"Scientists argue that gas isn't bad for you, but most people say it's not acceptable," says Slavin. "If you have gas, you should definitely consider what you're eating. If it's a lot of fermentable fiber or sugar alcohols, that could be the explanation."
MYTH: A gluten-free diet helps you lose weight and feel energetic.
In August, Lady Gaga told the Australian cable news channel Sky News that she was "on a mission to lose 10 pounds on a gluten-flee diet," according to The Huffington Post. The pop star was "hoping that eating wheat-free will give her the energy she needs to power through the remaining legs of her international tour."
When people who have celiac disease eat gluten--a protein found in wheat, barley, and rye--it triggers an abnormal immune response that damages the lining of the small intestine. That can cause diarrhea, cramps, pain, bloating, and vitamin deficiencies. Avoiding gluten, even tiny amounts, can allow the damage to heal.
But does going gluten free make the pounds melt away?
"There's no evidence from studies that that's true," says gluten expert Joseph Murray, a gastroenterologist at the Mayo Clinic in Rochester, Minnesota.
"When patients with celiac disease go on a gluten-free diet, some go up in weight and some go down, but most don't change. (3)
For people without celiac disease, it's not avoiding gluten, but the foods gluten comes in, that may matter.
"Whenever anyone goes on any restrictive diet, they typically end up eating less, because food is not so readily available," says Murray. "That's one of the major reasons we eat too much. Food is too available. If you go gluten free, it's not so easy to get fast food."
It's not just fast food that's not available. Suddenly, breads, bagels, pasta, pizza, burritos, pancakes, muffins, doughnuts, cupcakes, cookies, pies, pretzels, and dozens of other foods get wiped off your plate. What's left? For Lady Gaga, it was mostly fish, chicken, and vegetables.
"Is there something about wheat products or gluten-containing foods that causes weight gain beyond their calories?" asks Murray. "I don't think so."
Fatigue is a different story.
"For the great majority of patients with celiac disease, fatigue is a major symptom," notes Murray. "It may be partly due to vitamin deficiencies or to inflammation in the intestine. And it usually gets better on a gluten-free diet, though it takes weeks or months for the recovery."
But people without celiac may also report fatigue that diminishes on a gluten-free diet. Why?
"For one thing, you don't eat that great big carbohydrate with your midday meal," says Murray. "Certain foods that happen to be rich in gluten may produce sleepiness because of the carbohydrate load or calorie load."
That raises a different question: instead of seeing a doctor, should people with fatigue or stomach problems simply try a gluten-free diet to see if they feel better?
"That's not a good idea," says Murray. "First, if you do have celiac disease, it's much more challenging to get diagnosed if you're already on a gluten-free diet."
When the doctor takes a biopsy of the lining of your small intestine, it won't show damage if you've been off gluten.
And some people feel better on a gluten-free diet simply because they expect to. It's a placebo effect.
"About a third of people will respond for two or three months, and then the placebo effect wears off," says Murray. "They may feel better because they're eating less food or less junk food. But the symptoms could start coming back and then you're stuck in a diagnostic mystery."
Meanwhile, other problems could get worse. Trying a gluten-free diet "could delay a diagnosis of Crohn's disease," notes Murray. "Or, God forbid, it could be cancer, and the diagnosis gets delayed while they're on a gluten-free diet."
What's more, someone with celiac needs follow-up. (4) "We need to make sure that the damage to the intestine heals, and that nutritional deficiencies are gone," says Murray. "And family members need to be tested."
And a gluten-free diet isn't free. "There's the excess cost, the diet can be low in vitamins and fiber, which can lead to constipation, and it's a burden on family members."
Ironically, people who are eating a gluten-free diet aren't necessarily the ones who need to. Using blood samples from a nationally representative sample of roughly 7,800 people, Murray estimated the number of Americans with celiac. (5)
"We estimate that 1.8 million Americans have celiac disease, but only 17 percent of them know it," he says. Meanwhile, "1.6 million Americans are on a gluten-free diet, and the great majority of them do not have a diagnosis of celiac disease.
"The irony is that the people who have celiac disease and need to be on the gluten-free diet don't know it, and we don't know if many of the people who are on a gluten-free diet need to be on it."
There's one more complication: studies have found that some people without celiac get symptoms when they eat gluten. (6)
"We don't have a good test for patients with non-celiac gluten sensitivity," says Murray. "If they've been tested for celiac and don't have it, but their symptoms are not explained by anything else, I'd say it's worthwhile trying a gluten-free diet.
"I wouldn't do it for more than a month though," he adds. "I see people who come to me after a year on a gluten-free diet. They're totally convinced that they have gluten sensitivity, and I say, 'But you're no better than you were. Why don't you just go back to eating gluten?' And they say, 'But it's bad for me.' And I ask, 'How do you know that?' We're not always logical beings."
MYTH: Your colon needs cleansing.
Nature's Bounty Colon Cleanser promises to "Cleanse, Detox, Regulate." GNC's Preventive Nutrition Advanced Complete Body Cleansing 14-Day Program (only $39.99!) includes a "liver cleanser," a "gastro cleanser," and pills for "kidney health."
Those are just supplements you swallow. People who are more motivated can buy colonic irrigation kits from Web sites like homecolonics.com.
Do you need to clean your colon and other organs?
"There's no evidence that cleansing is helpful in any way," says Ranit Mishori, a physician and associate professor of family medicine at Georgetown University Medical Center in Washington, D.C.
"Our bodies are designed in such a way that, through the liver and kidneys, we cleanse all the toxins that are there," she explains. "The claims that you need to cleanse your body of toxins to reduce allergy, depression, or other problems are completely unfounded."
The idea that intestinal waste can poison the body began in ancient times, explained Mishori in a 2011 paper on the dangers of colon cleansing using colonic irrigation. (7) Cleansing was popular in the early 1900s until the American Medical Association condemned the practice in 1919. But in recent years, cleansing has made a comeback.
"Irrigation kits include a water tank and a hose, and one puts the hose, for lack of a better description, up one's rectum," says Mishori. "It's sort of an enema on steroids. It's a superduper enema."
All that water (up to 16 gallons) can cause cramps, nausea, vomiting, or worse.
Irrigation "can be extremely dangerous," says Mishori. "There are cases of perforation of the rectum or colon and infections that lead to abscesses and severe systemic infection.
"Most of the cases we see and all of the fatalities in the U.S. are related to this type of colon cleansing," she adds. "There have been lawsuits in Colorado, Florida, and Texas related to adverse outcomes from colon irrigation. Some ended in death."
Supplements are also heavily advertised despite no solid evidence of benefit.8 And although they're not as risky as irrigation kits, they can also cause problems.
"First of all, these supplements are meant to cause diarrhea, which is never a good thing," says Mishori.
"Diarrhea can cause dehydration, it can cause changes in minerals and electrolytes in the body. And if you have an underlying chronic condition like heart disease, liver disease, kidney disease, or low immunity, diarrhea can worsen it, leading to kidney failure or liver failure.
"The funny thing for me as a physician is that some people who ask me if they should do colon cleansing are reluctant to undergo a colonoscopy because of the prep," she says.
"In both cases, you're sitting on the toilet for two days, and it's uncomfortable. When it's for weight loss, it's okay, but when it's for cancer screening, it's not. I find that very odd."
No one knows how many people are harmed by colon cleansing, adds Mishori. "Many people probably use colon cleansing with no adverse effects. But some bad outcomes don't get reported because the doctors don't bother to write them up.
"People have incredibly stressful lives, whether it's because of their working life or family life or interpersonal relationships," she notes. "And there's this perverse thinking that if you just get some gunk out, by pooping it all out, it's going to make a huge difference in your life.
"So many other interventions are proven and safe--yoga, exercise, walking, talking, and even having a glass of wine," says Mishori. "Why do we have this need to detoxify and get the gunk out?"
MYTH: Most adults can't digest the lactose in a glass of milk.
Lactose is the naturally occurring sugar in milk. But many adults no longer have the enzyme lactase, which breaks lactose down into glucose and galactose.
Instead, the undigested lactose passes into the colon, where bacteria ferment it and release gas. And if there's enough lactose, it can also draw water into the colon, causing diarrhea.
But many people without lactase can drink up to a cup of milk at a meal without symptoms of lactose intolerance--usually abdominal pain, bloating, and diarrhea. (9,10)
You're less likely to have symptoms if your stomach empties slowly. "The rate of stomach emptying is genetically controlled, and we vary," explains Richard Grand, professor of pediatrics at Harvard Medical School.
"Fat reduces the rate of stomach emptying," he notes. "So if you drink fat-free milk alone or with a low-fat meal, you may have symptoms." But if you drink it with a typical meal, which contains fat, the symptoms may not appear.
And you can grow more lactose-loving bacteria--the kind that break down lactose without fermenting it and giving off gas.
"Often people who have lactose intolerance adapt to a little lactose in their diet, because the bacterial flora in their colon can 'learn' to digest the lactose," says Grand, who is also director of the Inflammatory Bowel Disease Center at Children's Hospital in Boston.
"These people may have a lactase deficiency in their small intestine, but their bacteria can break the lactose down, so they don't have symptoms."
To build up your lactose-digesting bacteria, start with small amounts of milk. "Maybe a tablespoon, then build up to a glass per meal over three to six weeks," suggests Grand. "See how much you can tolerate."
It's also possible that your symptoms aren't due to lactose.
"The best studies give people milk, and then give them an identical product with glucose instead of lactose," Grand explains. "The majority of the time, they can't tell which milk they've been given. The clinical symptoms in a large percentage of those people are equal."
One explanation: many people who complain of lactose intolerance may actually have irritable bowel syndrome. (11)
"Irritable bowel syndrome has similar features--abdominal pain, usually shortly after eating, and then either constipation or diarrhea during the day," says Grand. "So it's common for them to be confused.
"Lactose intolerance is over-diagnosed," he adds. "People diagnose themselves, and they shouldn't."
Another mistake: some people assume that if they're lactose intolerant, they need to avoid all dairy. That's not so:
* Cheese. "Hard, unprocessed cheeses like real cheddar and Swiss don't have much lactose," says Grand. (See "Looking for Lactose," p. 5.)
Processed cheese slices may have added whey and other milk ingredients, though. So does Kraft Macaroni & Cheese. But if the Nutrition Facts list no more than I or 2 grams under "Sugars," you're probably safe.
* Yogurt. Yogurt is made from milk, but the yogurt's cultures turn some of the milk's lactose into lactic acid. "Yogurt has that tangy taste because the culture has Lactobacillus and other good bugs that break down lactose," explains Grand.
And most of the lactose that's left gets broken down by the yogurt's bacteria once it reaches your gut. (12)
"But many flavored yogurts have milk or milk solids added for taste," notes Grand. So they have extra lactose. (Check the ingredients to see if a yogurt has added milk solids or whey.)
* Enzymes. If your body doesn't make its own lactose-digesting enzymes, you can buy them in pills like Lactaid, Lactase, and Dairy Relief.
"Taken with milk, or even a little bit before milk, they work quite well," says Grand. "Some brands are better for one person than another, so if one doesn't work, try another."
MYTH: All fiber supplements are equally good at keeping you regular.
"Promotes regularity," says the label of Walgreens Fiber Select Gummies. VitaFusion Fiber Well Gummies "help support regularity." "Therapy for regularity," says the Metamucil canister.
To the average consumer, all fiber supplements may appear equally good for regularity. But they're not.
"Wheat bran and psyllium are the best for increasing stool weight," says the University of Minnesota's Joanne Slavin.
"If you look at fibers that have the most effect on stool weight, about half the fiber gets broken down in the gut, but half is still there by the end, so it's going to hold water and make a bigger stool."
For every gram of the fiber in wheat bran you swallow, for example, stool weight increases by about five grams. That's also true for psyllium, the fiber in Metamucil23
Other fibers have less impact on stool weight. "When we gave people 20 grams a day of soluble corn fiber or polydextrose, the increase in stool weight was about 25 percent of that seen with wheat bran," explains Slavin. (That study has yet to be published.)
And 20 grams is quite a bit. A daily dose of VitaFusion Fiber Well Gummies, for example, has just five grams of polydextrose.
"Some of these regularity claims are misleading because people get less than what they're expecting," acids Slavin.
Inulin may also be disappointing.
"Inulin has no effect on stool weight," says Slavin. "It's completely fermented, so by the end of the ride, there's nothing left." That's what she found when men were fed a large dose of inulin--20 grams a day. (14) (Each Walgreens Fiber Select Gummy has 2 grams of inulin.)
"But for someone who's constipated," notes Slavin, "inulin could speed things up, because it's fermented quickly. The fermentation and short-chain fatty acid production could bring some water into the colon and loosen things up."
That's largely speculation, she adds, because no one has done good studies. "A couple of studies have been done in the elderly, but the effects are self reported."
Slavin's bottom line: "Fibers are not alike, even though it looks like they're the same on the label. In the physiology world, they're quite different."
MYTH: Nuts, seeds, and popcorn lead to diverticular disease.
Stay away from nuts, popcorn, corn, and caraway, sesame, sunflower, pumpkin, and other seeds. That's what doctors told patients with symptoms of diverticular disease until 2008.
That's when a study that tracked 47,000 men for 18 years found a lower risk of diverticulitis or diverticular bleeding among men who ate the most popcorn or nuts than among those who ate the least, and no link with corn or seeds. (15) Yet the myth persists ... and not just among the public.
"I still see patients whose physicians have recommended that they don't eat those foods," says Lisa Strate, the assistant professor of gastroenterology at the University of Washington School of Medicine who led the study.
"The theory was around for decades, although it was unsubstantiated, and only our one publication suggested that these foods really don't increase the risk. So I think it's still a very common belief."
While some people are distracted by nuts and seeds, they should be worried about other risk factors.
"More than 50 percent of adults will develop diverticulosis by the age of 60," explains Strate. "That's the condition of having pockets or sacs in the colon." They typically cause no symptoms.
"It's much less common to develop bleeding or diverticulitis, which is inflammation of one or a few of these pockets," she adds.
Those complications strike 10 to 35 percent of people with diverticulosis, ac cording to some estimates. "A recent, as yet unpublished, study suggests that it's more along the lines of 1 percent," notes Strate. "But even if I percent of people with diverticulosis have complications, it's still a common problem."
So far, researchers know more about what leads to inflammation or bleeding than about what causes the pockets in the first place. Among the risk factors for complications:
* Too little fiber. In a study that tracked roughly 47,000 people in Eng land and Scotland for 12 years, those who consumed the most fiber (at least 26 grams a day) had a 40 percent lower risk of being hospitalized for diverticular disease than those who ate the least fiber (less than 14 grams a day). (16) The Health Professionals Follow-up Study of 48,000 U.S. men found nearly identical results. (17)
"Individuals who are on a low-fiber diet appear more likely to get diverticular complications," says Strate.
However, she notes, "it doesn't look like low-fiber diets lead to diverticulosis." Eating too little fiber may only boost the risk of complications.
* Obesity. When researchers monitored roughly 36,000 Swedish women for 12 years, those who were either overweight or obese had about a 30 percent higher risk of being hospitalized for diverticular disease.18
And when Strate tracked the 48,000 U.S. male health professionals for 18 years, those who were obese had nearly double the risk of diverticulitis and triple the risk of bleeding compared to those who were normal weight. (19) The risk also rose with increasing waist size, especially with a waist over 40 inches.
Why is belly fat worse? "It's more metabolically active," says Strate. "It produces more molecules that may increase inflammation in the colon."
* Inactivity. Among the U.S. health professionals, men who ran at least three hours a week had a 34 percent lower risk of diverticulitis and a 39 percent lower risk of bleeding than men who did no vigorous exercise. (19) Likewise, the Swedish women who got more than 30 minutes of exercise a day had a lower risk than those who got up to 30 minutes a day. (18)
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(6) Am. J. Gastroenterol. 106: 508,516, 2011.
(7) J. Family Pract. 60:454,2011.
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(9) N. Engl. J. Med. 333:1,1995.
(10) Curl: Treat. Op. Gastroenterol. 11: 19, 2008.
(11) N. Engl. J. Med. 310: 1,1984.
(13) Am. J. Clin. Nutr. 72: 784, 2000.
(14) Food Funct. 2:72,2011.
(15) JAMA 300: 907, 2008.
(16) BMJ. DO1:10.1136/bmj.d4131.
(17) Am. J. Clin. Nutr. 60: 757, 1994.
(18) Am. J. Gastroenterol. 107: 296, 2012.
(19) Gastroenterol. 136:115, 2009.
(20) Am. J. Gastroenterol. 104: 1221, 2009.
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|Publication:||Nutrition Action Healthletter|
|Date:||Jan 1, 2013|
|Next Article:||Eat your veggies.|