How healthy is going gluten-free, the latest fad diet?

"I suggest avoiding gluten," is the advice given by Mark Sisson, author of "The Primal Blueprint," on his popular health and nutrition blog, Mark's Daily Apple.

Sisson believes gluten intolerance is more common than we realize; his theory is that gluten and grains have been introduced relatively recently into the human diet, so it's a smart idea to drop them altogether.

Sisson is not alone in his beliefs.

Elizabeth Hasselbeck, co-host of "The View" and author of the "G Free Diet," purports that a gluten-free diet can increase energy, lower cholesterol, help you lose weight and restore health. A growing number of people are placing gluten, the protein found in wheat, rye, barley and triticale, on their "no" list, in much the same fashion as they once banned fat and carbohydrates.

"It's definitely a hot trend for people to go off gluten. It's like the latest Atkins diet," says Shelley Case, gluten-free nutrition expert and author of "Gluten-Free Diet, A Comprehensive Resource Guide." Case reports that the gluten-free products market increased from $560 million in annual sales in 2004 to $1.56 billion in 2008, and is expected to climb to $26 billion in 2012.

Going completely gluten-free is a dire necessity for people diagnosed with celiac disease, a lifelong digestive disorder. When people with CD eat gluten-containing foods, it creates a toxic reaction from the immune system that causes damage to the small intestine and does not allow food to be absorbed properly. Even small amounts of gluten can affect people with CD.

CD affects one out of 100 people, making it "the most underdiagnosed disease in America," Case says. A Mayo Clinic study published in July 2009 in the journal Gastroenterology revealed that CD is at least four times more common now than it was 50 years ago. Though researchers don't understand why rates of CD are climbing, some say it might be related to our increasingly high intakes of gluten and wheat.

Other gluten-free followers are those with non-celiac gluten sensitivity (an intolerance to gluten with symptoms such as bloating, abdominal pain and diarrhea) and people with a wheat allergy who must avoid gluten-containing wheat products.

Case notes that there's little scientific support to back the claims that humans should eliminate gluten, but she concedes that we're eating gluten at unprecedented levels.

"We are eating a lot of gluten in processed foods and things like bagels, muffins and snack foods. We're carbaholics. We don't eat the same way our grandparents did - they ate smaller amounts of gluten, and primarily in the form of bread," says Case. Cutting back on high amounts of gluten in wheat products - especially in refined, processed foods - is pretty sound advice for an optimal diet. Nevertheless, the notion that gluten-free equals healthy is a mistake.

"Many people gain weight because gluten-free products mostly contain starches, sugars and fats, and the majority of gluten-free foods are not enriched with vitamins and minerals as wheat products are," Case said. "People tend to feel deprived when they're on a gluten-free diet, so they often eat more gluten-free baked products, like cookies."

On the other hand, a gluten-free diet can be a model of health with just a little effort, by forging a diet around lean proteins, low-fat dairy products, legumes, nuts, fruits, vegetables and ancient gluten-free whole grains like quinoa.

Consider going gluten-free? First review the symptoms of celiac disease and see if they apply to you, Case suggests. If they do, talk to your doctor about a blood test or small intestine biopsy for an accurate diagnosis.

If results indicate you don't have CD, you might consider trying a gluten-free diet anyway to see if you get any relief. If you do have CD, meet with a registered dietitian to help you plan a healthy gluten-free diet.