TUESDAY, Feb. 21 (HealthDay News) -- Gluten-free diets have become a popular way to manage gluten sensitivity, but a new analysis suggests that many people who stop eating gluten may not need to do so.

Health experts have claimed that this special diet can ease digestive ills in those who are sensitive to gluten, a substance found in wheat, barley, rye and possibly oats. Some even think avoiding gluten might reduce headaches, fatigue, hyperactivity and autism symptoms.

However, when comparing the number of mentions of gluten sensitivity on Google to the number of scientific articles on the subject, Italian researchers found that the Google mentions far outweighed mentions in the medical literature, at a ratio of 4,598 to one.

"Clinically, we see a lot of suspicion that gluten reactions are responsible for numerous health problems, and it's difficult to counter this belief. There are a lot of alternative practitioners out there that blame gluten for everything, even though there's not a lot of science behind it," said Dr. Joseph Levy, division director of pediatric gastroenterology at New York University Langone Medical Center in New York City.

In the article, published in the Feb. 21 issue of the Annals of Internal Medicine, the Italian researchers explain that gluten has become "the new diet villain" in the United States. American marketers claim that 15 percent to 25 percent of consumers want gluten-free foods, and popular estimates suggest that as many as 17 million Americans are gluten-sensitive. However, there's no official data on the prevalence of gluten sensitivity in people who don't have celiac disease, according to the study authors.

Celiac disease is an autoimmune condition that damages the lining of the small intestine when gluten is eaten. This damage prevents the small intestine from absorbing the nutrients in food, and people with celiac disease slowly become malnourished. It's essential that anyone with celiac disease maintain a gluten-free diet; even occasional slips can cause damage.

Levy said there's no question that some people appear to have what the researchers dubbed nonceliac gluten sensitivity. "Some people, when you remove gluten, have less gas, belly aches and nausea," he said.

But, he added that it might not be the gluten that's the problem, and could instead be something else in foods containing gluten.

Another digestive expert, Dr. David Greenwald, isn't convinced yet. "It's very hard to tell if someone has nonceliac gluten sensitivity. I have a healthy skepticism until there's a scientific basis for the diagnosis. It's very easy to jump on the wave, but the authors here are saying to wait for the scientific evidence that there is a sensitivity that's not based on celiac disease," he explained. Greenwald is a gastroenterologist at Montefiore Medical Center in New York City.

Greenwald said that a lot of people who try gluten-free diets do so because they're having symptoms that suggest irritable bowel syndrome (IBS), such as abdominal pain, gas and bloating.

"Most of the people who come to the conclusion that they have nonceliac gluten sensitivity have IBS symptoms, and they've heard that a gluten-free diet might help them, and a number of them start feeling better when they eliminate gluten," said Greenwald. But, in clinical trials, people with IBS often have high placebo success rates, sometimes more than 30 percent, he said. So, for some, going on a gluten-free diet might induce a placebo effect.

Levy agreed. "Physiological changes can occur with positive thinking. If, for whatever reason, someone is convinced that removing gluten will help, and it does, that's fine," he said.

The good news is that a gluten-free diet is generally considered safe. It's helpful to work with a nutritionist to ensure you're getting all the necessary vitamins and nutrients if you decide to undertake a gluten-free diet. And, Levy advised reading ingredient lists on gluten-free products. Some are made with beans, which could cause gas and bloating if eaten in significant quantities.

The only significant downside to gluten-free diets is cost, since gluten-free foods are significantly more expensive than foods that contain gluten.

"If people are uncomfortable and want to put themselves on a gluten-free diet and they don't mind it, there's no real harm to that if they're willing to bear the inconvenience and cost," said Greenwald.

However, both experts cautioned that it's important that a doctor rules out celiac disease before anyone undertakes a gluten-free diet. Lowering the amount of gluten in your diet can change the results of the blood tests used to screen for celiac disease, and might mask the presence of celiac disease. With celiac disease, it's essential to avoid all gluten to avoid complications.

More information

Learn more about food allergies and intolerance from the American Gastroenterological Association.