Food Allergy and Intolerance Guide

It's tough to host a dinner party these days, given everyone's digestive challenges: No gluten. No dairy. No sugar. No wine or beer with sulfites. What's going on?

Gastrointestinal experts call it food intolerance, and it's increasingly an issue. Some estimate that 10 to 25 percent of Americans have a sensitivity to at least one food, while others say the prevalence is much higher. 

"Percentages are only guesstimates at this point," explains Steven M. Dandalides, M.D., a spokesperson for the American College of Gastroenterology and an assistant clinical professor at Eastern Virginia Medical School in Norfolk. "Judging by the number of people who come to see us, this seems to be a common problem."

When seemingly good foods are sidelined, it's hard not to question whether food intolerance is really a problem of the gut or simply an excuse for picky eaters. New research points to just how common it is -- and how to cope if you're diagnosed. 

Intolerance Versus Allergies
To understand what food intolerance is, you first have to understand how it differs from allergies. An allergy is an immune-system response in which your body mistakes a certain food for a harmful invader and creates antibodies to fight it. 

Symptoms can be mild or life-threatening -- from nausea and hives to shortness of breath and anaphylaxis -- and tend to come on immediately. According to the American Academy of Allergy, Asthma, and Immunology, only 3 to 4 percent of adults in the U.S. have a true food allergy. 

Unlike an allergy, a food intolerance is a response from the gastrointestinal system. When certain foods are poorly absorbed from the intestines into the bloodstream, the result can be symptoms like gas, bloating, diarrhea or constipation, nausea, or abdominal pain one-half to eight hours after consumption. 

Another big difference: Food intolerances are often but not always dose dependent. This means that even if you're predisposed to intolerance for a food, you can likely eat a certain amount of it without experiencing an unpleasant GI reaction -- and that dose varies by individual.

Another misconception: You don't necessarily have an intolerance if you get gassy and bloated after drinking milk or eating pasta. (Though these days, having a food intolerance seems almost fashionable.) You'll need to see a medical professional to determine whether you really have a food sensitivity, and if you eliminate suspect foods without seeing a doctor, you'll likely miss out on vital nutrients. 

"If you're not gluten intolerant, a gluten-free diet is not healthier," stresses Stefano Guandalini, M.D., a food-intolerance specialist who is director of the University of Chicago Celiac Disease Center. Restricting your diet unnecessarily can keep you from getting an accurate diagnosis of a more serious condition.

Why the Rise?
There's been a great deal more food-intolerance research in Europe than in the U.S., yet the cause is still somewhat mysterious. There are a couple of respected hypotheses: One is that as we evolved from hunter-gatherers and began eating foods we produced ourselves, such as wheat and cow's milk, some of us weren't able to adapt and developed intolerances. 

Other experts say that the food we eat today is too "clean." 

"We don't get exposed to good bacteria found in places like soil anymore," says Scot Lewey, D.O., a Colorado Springs gastroenterologist and fellow at the American College of Gastroenterology. 

Chemicals purify our water; we don't eat fresh-picked produce; our meat has been dosed with antibiotics to keep it disease-free. Plus, we're now more likely to consume commercially processed multi-ingredient foods, increasing the number of potential irritants. 

Anxiety and poor lifestyle habits can also take a toll on your GI tract. 

According to the American College of Gastroenterology, the primary intolerance culprits are foods containing lactose, gluten, and fructose. Here's how they all break down. If one of these descriptions resonates with you, you might want to make a doctor's appointment.

Lactose Intolerance
Dairy products give an estimated 30 million to 50 million Americans gas, bloating, diarrhea, nausea, or cramps. By far the most common food sensitivity, lactose intolerance occurs when the small intestines don't produce enough lactase, the enzyme that helps the body digest lactose, the sugar in milk products. 

There's a generally accepted evolutionary theory to back it up: Before the advent of dairy processing, most humans never drank milk after being weaned, and so some people's GI tracts didn't bother to make much lactase postchildhood -- which explains why most sufferers develop symptoms as adults.

How Do You Know You Have It?
Your doctor can administer a breath test, because undigested lactose produces detectable hydrogen, but experts agree that the best way to tell if you're lactose intolerant is with a supervised elimination diet. Avoid milk and dairy -- including ice cream and cheese -- for several weeks. If symptoms abate, your M.D. or R.D. will ask you to rechallenge your GI system with a lactose food. If symptoms return, you're most likely intolerant.

How to Cope
No other food offers the nutritional bonanza found in milk products, which contain calcium, vitamin D (when fortified), protein, potassium, and magnesium. Fortunately, you can have your milk and drink it, too.

Switch to low- or no-lactose dairy. Opt for milk that contains no lactose but still meets 25 to 30 percent of your daily needs for calcium and vitamin D. Buttermilk, aged and hard cheeses, and goat's milk have less lactose than cow's milk and are easier to digest. Soy milk, too, can be a healthy substitute. (For a treat, try this Cappuccino Swirl Shake made with almond milk.)

Pop a supplement. A lactase-enzyme supplement, taken with your first sip or bite of dairy, can help your system digest the lactose.

Consume dairy with meals. The National Institutes of Health says that most people can drink half a cup of milk without experiencing nasty GI symptoms, particularly when it's consumed at meals or alongside other foods.

Try yogurt and kefir. This sounds counterintuitive, since both are lactose-containing dairy products. But studies have shown that the probiotic cultures in these foods help break down lactose and, consequently, aid the digestion of the lactose in the yogurt and kefir.

Gluten Intolerance
Gluten, a protein found in wheat, rye, barley, spelt, and triticale, is used by grain to grow and reproduce. It's what gives dough its elasticity and allows it to rise. But even foods that aren't bakery products, such as ice cream or ketchup, can contain small amounts of gluten, which is often used as a thickener. 

For the intolerant, gluten can set off some really icky GI symptoms within minutes or hours of ingestion; some sufferers even report depression and brain fog.

These symptoms should in no way be confused with celiac disease, which is an autoimmune disorder. When someone with celiac eats even the tiniest amount of gluten, the immune system attacks the small intestine and prevents absorption of vital nutrients, which may lead to malnutrition. Unlike celiac sufferers, the gluten-sensitive can tolerate small doses.

How Do You Know You Have It?
It's not a good idea to forgo gluten if you don't need to. Whole grains, like wheat and rye, are excellent sources of complex carbs, fiber, potassium, and magnesium. If you suspect you have gluten sensitivity, first rule out celiac disease, which can be diagnosed with a blood test and intestinal-lining biopsy. (There's no specific medical test for gluten sensitivity.) Eat as you normally would before you visit your doctor; you'll need some gluten in your system so the tests can detect celiac if you have it. If the test is negative, your doctor will recommend an elimination-reintroduction diet. (Learn more about going gluten-free here.)

How to Cope
For the gluten-sensitive, simply eliminating some major sources should relieve symptoms. There are also several cookbooks that cater to the gluten-free crowd.

Scrutinize labels. Watch for these gluten synonyms: barley, malt or malt flavoring, malt vinegar, rye, triticale, wheat, durum, graham, Kamut, semolina, spelt, modified food starch, caramel, and flavor enhancers.

Get creative with whole grains. Substitute traditional breads, pastas, and cereals with gluten-free grains and plant products, like rice, corn, soy, potato, tapioca, beans, quinoa, millet, and buckwheat substitutes. (Get healthier grain recipes, many of them gluten-free, here.)

Say "cheers" with wine or hard liquor. Avoid beer, ale, lager, and other malt beverages made from wheat or barley.

Try probiotics. "Pretreating with lactobacillus and acidophilus may make gluten less toxic," Lewey says. If you're concerned about accidentally consuming gluten, take these probiotics before eating. It could be helpful. 

Fructose Intolerance
Fructose is a sugar found naturally in just a few foods, primarily fruits. It's also a major component in table sugar and high-fructose corn syrup. The term "fructose intolerance" is used to describe two very different conditions. The first is hereditary fructose intolerance (usually diagnosed in childhood), a rare genetic disorder in which the enzyme that breaks down fructose is missing. 

More common and much less serious is dietary fructose intolerance -- an inadequate ability to digest fructose that causes abdominal cramping, gas, bloating, burping, and diarrhea -- which experts say is on the rise because of our sweets-guzzling culture.

How Do You Know You Have It?
You can try an elimination diet, or take a breath test. If you've been diagnosed with or suspect you have irritable bowel syndrome, you may want to ask your doctor about fructose intolerance. In a Journal of Clinical Gastroenterology study, one-third of the participants with IBS tested positive for it.

How to Cope
Forgo foods and drinks sweetened with high-fructose corn syrup, sugar, fruit juice, honey, and agave.

Eat one fruit serving at a time along with other foods. According to a 2006 study in the Journal of the American Dietetic Association, people who staggered fruit consumption throughout the day experienced far fewer gastrointestinal symptoms. The ADA also recommended that fruit be eaten at meals, which enhances absorption.

Opt for stone fruits, berries, citrus, bananas, kiwi, passion fruit, pineapple, and rhubarb. These fruits contain equal amounts of fructose and another sugar called glucose, which makes them easier to digest, according to the ADA.

Watch out for foods with artificial sweeteners. Diet foods, beverages, and gums are sweetened with sugars (such as sorbitol, mannitol, and xylitol) that your GI tract can't absorb well whether you have fructose intolerance or not. Eat them only occasionally.

Quit gobbling. By consuming your food slowly, you won't overload the small bowel, Lewey advises. Whether you have food intolerance or not, slowing down and paying attention to what you eat is the basis of good digestion. You're never going to diagnose -- much less fix -- anything until you make the time to start listening to your body. "Eat healthy foods, get enough sleep, meditate, exercise daily, and take a holiday from technology," Lewey says. Good advice for all of us.

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