How to pinpoint the problem

Rule number one: Don’t self-diagnose, says Jeanette Keith, MD, spokeswoman for the American Gastroenterological Association. Instead, work with a trusted health professional to identify the problem and map out the healthiest way to manage it. Follow these steps with your provider.

1. Rule out celiac disease

Although it presents much like a food intolerance or allergy, celiac disease is actually an autoimmune disorder that’s aggravated by gluten, a protein found in wheat, barley, and rye. “Celiac disease is an in-between category,” says Robert Wood, MD, chief of allergy and immunology at The Johns Hopkins Children’s Center in Baltimore. “It’s not considered an allergy, but it involves the immune system, so it’s more than intolerance.”

Celiac symptoms often resemble those of sensitivity to gluten or lactose, Keith says. Undetected, this disease can lead to nutrient deficiencies, diabetes, gastrointestinal (GI) tract malignancies, and even small-bowel cancers, she warns. “Not everything that rumbles is lactose intolerance. So if you have diarrhea or an irritable bowel, get checked for celiac disease. I worry about this diagnosis being missed.” In fact, a recent study published in the American Journal of Gastroenterology found that nearly 2 million Americans have celiac disease, but close to 80 percent don’t know it.

Blood tests and small-bowel biopsies usually detect celiac disease but must be performed while you’re still eating gluten, says James Li, MD, chair of allergic diseases at the Mayo Clinic in Rochester, Minnesota. Genetic tests can also reveal whether you’re at risk for celiac (or unlikely to have it). If you have celiac disease: Although there’s no cure, you can manage the condition by eliminating gluten from your diet. Go to for gluten-free resources.

2. Test for allergies

Once you’ve ruled out celiac, get tested for food allergies. According to the American College of Allergy, Asthma & Immunology, food allergies can show up at any age, though they are far more common in babies and children (who often outgrow them). If you eat a food you’re allergic to, your immune system will immediately identify it as an invader and attack its proteins and polysaccharides by cranking out histamine, triggering allergic reactions such as swelling, rashes, runny nose, itchy eyes, and even anaphylaxis, a whole-body, potentially fatal backlash.

About 4 percent of adults have a true food allergy. It’s rare, but possible, for a food allergy to cause GI issues only; skin and respiratory symptoms usually show up, too, says Wood. But sometimes symptoms are nearly undetectable. “With lower-grade allergies, there may be no acute symptoms, but continued exposure can cause chronic GI inflammation and long-term problems,” Wood says. Plus, “allergies can definitely get worse; one reaction doesn’t predict the next one.” Though tests aren’t 100 percent accurate, they can point you in the right direction. “Blood or skin-prick testing [comes first] to see if there’s an immune reaction to food,” Wood says. And although tests might rule out some allergens, they may reveal an allergy to an unsuspected food—or several. Plus, finding out what you’re not allergic to lets you reintroduce a food you’ve been avoiding.

If you have a food allergy: Any trace of a food allergen can trigger a response, Wood says. He stresses strict avoidance, which requires diligence. “Complete avoidance can make a big difference in your day-to-day life—how close of attention you pay to ingredient labels and how much you quiz restaurants about their ingredients.” The Food Allergen Labeling and Consumer Protection Act of 2004 made listing common allergens in plain language mandatory on food packaging. But also keep an eye out for flours, syrups, sugars, and other ingredients derived from your allergen, and research additional foods that are made with or contaminated by it.

3. Determine intolerances

Not allergies? Then you likely have an intolerance to one or more foods, typically because your body makes too little of an enzyme required to digest it thoroughly. Intolerance can also occur if your system struggles to absorb a specific ingredient, if you have a negative but nonallergic reaction to chemicals like salicylates, or if you have leaky gut syndrome. The intolerance spectrum ranges from a total inability to digest a food to being able to stomach small amounts. Common symptoms include cramps, diarrhea, and other GI woes, but a food may also trigger respiratory, skin, and behavior issues, says Li.

Although not life threatening, intolerances can hinder health. By not metabolizing a food properly, you’re missing out on key nutrients and stressing your body. “When you keep eating something that doesn’t agree with you, your digestive tract gets worn down,” says Anne Kelty, ND, of Swampscott, Massachusetts. “It’s like if you scrape your finger on sandpaper once, it causes little harm. But if you keep doing it, your finger gets red, sore, and bloody.”

If you have a food intolerance: Carefully observe your diet with your doctor or dietitian. “I give my clients a diet diary to keep track of everything they eat and how they feel for two weeks,” Kelty says. “Sometimes symptoms don’t show up right away. You might eat wheat on Tuesday but not have bloating or swelling until the next day. A diary reveals patterns or combinations of foods eaten consistently that may be causing problems.”

Next, Kelty suggests eliminating suspect foods for four to six weeks. Once you feel better, add in one food at a time, at your health care provider’s suggestion, to identify triggers. Figuring out which foods trouble your system and adjusting your diet can seem daunting, but you’ll ultimately feel healthier than ever.