It's one of the hottest trends in the food industry: gluten-free.
All manner of products -- cereal, cake mix, even beer -- are making the jump from niche stores to the nation's biggest supermarkets. Celebrities have touted a gluten-free diet as way to lose weight and feel healthier. Big food manufacturers have started investing heavily, with General Mills leading the way.
Yet for most of the population, there's no proof that a gluten-free diet offers any benefit -- and it's more costly.
"There are a lot of misconceptions about the gluten-free diet out there," said Whitney Ehret, communications director for the National Foundation for Celiac Awareness.
The foundation represents the small group of people for whom the growing variety of gluten-free foods is a godsend -- those with celiac disease or gluten sensitivities. Celiac sufferers' diets must be free of gluten, a protein found in wheat, barley and rye, while those sensitive to gluten should avoid it.
But celiacs and the gluten-sensitive make up only about 6 percent of the U.S. population.
Gluten, an essential component in making cakes fluffy and cookies chewy, has in a way become demonized. Some products billed as gluten-free don't even contain gluten to begin with, but marketers want to capitalize on the sudden health halo.
Carol McCarthy Shilson, executive director of the University of Chicago's Celiac Disease Center, said retail sales of gluten-free products rose from an estimated $935 million in 2006 to an estimated $2.64 billion in 2010, according to a February report by Packaged Facts, a market researcher.
Datamonitor's Product Launch Analytics, another market researcher, found that 13.4 percent of all food products launched in 2010, excluding beverages, made a gluten-free claim, compared with 5 percent in 2005. "It's pretty unusual to see that sort of major advance over that brief a period of time," said Tom Vierhile, Product Launch Analytics' director.
Dominic Alcocer, General Mills' marketing manager for new ventures, said the company dove headlong into the market after questions about gluten-free products and ingredients began to top its consumer hotline.
Beginning in 2008, General Mills reformulated its Chex cereal line -- except Wheat Chex and Multi-Grain Chex -- to be gluten-free.
A gluten-free version of the company's Bisquick was launched last year, and Betty Crocker was the first national brand to offer gluten-free versions of brownie, cookie and cake mixes in traditional grocery stores.
For people with celiac disease, gluten causes the body to attack itself by destroying "villi," tiny fingerlike protrusions lining the small intestine that are vital for absorbing nutrition.
About 1 percent of the U.S. population has celiac disease. The number of gluten-sensitive people is thought to be four to five times higher, Shilson said.
In a survey done last fall by Packaged Facts, 20 percent of consumers said they bought gluten-free products because a member of their household had celiac disease or was gluten-sensitive. But 46 percent purchased gluten-free for the perceived health benefits.
Another 30 percent said they bought gluten-free to manage weight, while 22 percent purchased gluten-free goods because they believed they are lower in carbohydrates.
The Packaged Facts report notes that neither the weight-management nor lower-carb claims are true. "But consumers tend to think otherwise." One of the reasons is the buzz bestowed by celebrities on a gluten-free diet, market analysts say.
Gwyneth Paltrow has talked about her cleansing regime -- several days free of caffeine, dairy products, processed food and gluten. Oprah Winfrey went on a no-gluten cleansing diet.
Shilson said that gluten-free diets "can cause you to be undernourished or gain weight." Gluten-free foods also can contain less vitamins and fiber than their gluten-containing counterparts. And sometimes, fat, sugar and salt may be added to gluten-free products to help replace taste or texture imparted by gluten.
Plus, because of reformulation costs, gluten-free products on average are two to three times more expensive than their gluten-containing counterparts, according to the National Foundation for Celiac Awareness.
Food fads come and go. The low-carb craze crashed around 2004 and burned a lot of companies that jumped on the bandwagon late, said Vierhile. But if a company takes a leading position in the gluten-free market now, it's much more likely to soldier on even if the trend turns out to be a fad, he said.
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