It’s getting easier to "go gluten-free" when dining out because more restaurants are offering dishes designed for customers with celiac disease or a gluten sensitivity. According to Mintel, a marketing research company, mentions of gluten-free options on restaurant menus increased by 275 percent between 2009 and 2012. Whether it’s a menu listing for alternatives such as gluten-free bread and gluten-free beer, or a notation that certain dishes can be made without croutons or breadcrumbs, restaurants are helping to make it easier for these diners.

Gluten is a protein found in wheat, barley, rye and possible oats. Oats do not contain gluten but are often milled in a facility that processes gluten-containing grains.

May has been designated Celiac Awareness Month. Celiac disease is an immune reaction to gluten that damages the lining of the small intestine and affects an estimated 3 million (one in 133) people in the United States.

Meanwhile, 18 million Americans — six times as many as in the celiac group — are classified as having non-celiac gluten sensitivity. Add to that folks who may not be diagnosed with a gluten intolerance but just want to avoid it, and the number of Americans who want to reduce or eliminate gluten from their diets in 2013 swells to one in three, according to the NPD Group, a consumer market research company.

Jessie Lagasse Swanson and Jillian Lagasse, daughters of famed New Orleans chef Emeril Lagasse, both follow a gluten-free diet and co-authored "The Gluten Free Table" cookbook.

Swanson said dining out can be a challenge, but she has learned to ask a lot of questions about ingredients.

"It takes persistence and perseverance, but after a while it becomes second nature to you."

She said it’s great that increased demand has led to a wider choice of better-tasting gluten-free products, but that doesn’t make them a healthier choice.

"Some foods, like gluten-free boxed cookies, can still be really high in fat and calories," Swanson said.

Just as folks with allergies to certain foods such as nuts or shellfish have to be vigilant about avoiding offending ingredients, those with celiac disease or gluten sensitivity have to become diet detectives when dining out. Don’t assume that anything is gluten-free. The chef may have added a "secret ingredient," so always let your server know you can’t have gluten-containing products. For instance, fries or potato skins might be dusted with flour to make them crispier.

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CLUES TO GLUTEN WITHIN

Au Gratin: topping of bread crumbs.

Battered: coating contains wheat flour.

Bechamel sauce: thickened with wheat flour.

Bisque: soup often thickened with flour.

Croquette: encased in breadcrumbs.

Fricassee: stew usually thickened with flour.

Marinade: may contain soy sauce or condiments with gluten.

Roux: paste of fat and flour to thicken sauces.

Salad dressings: can be thickened with wheat-containing ingredients.

Streusel: made from flour, butter, sugar and spices.

Teriyaki sauce: contains soy sauce.

Tempura: fried in a flour-based batter.