What exactly does it mean for food to be "gluten free?" The answer is especially important for those suffering from celiac disease, an autoimmune illness that makes sufferers unable to digest gluten.

Today the U.S. federal government has set a new standard for food companies labeling their products gluten free, a change that health officials expect will help three million Americans with celiac disease and create uniformity within the $4 gluten free market, the New York Times reports.

Gluten, a composite of starch and proteins that occurs naturally in grains such as wheat, barley and rye, can trigger the production of antibodies that damage the lining of the small intestine in people with celiac disease. In 2004, Congress passed a law requiring the Food and Drug Administration to trace the amounts of gluten in food products before labeling them gluten free. Since 2007, all foods labeled "gluten free" must contain fewer than 20 parts per million of gluten.

Now, with the FDA's new rules announced today, consumers can be "assured that those claims have meaning," said Michael Taylor, the FDA's deputy commissioner for foods and veterinary medicine.

It's a serious issue to tackle, as those suffering from celiac disease can develop nutritional deficiencies, osteoporosis, growth retardation, infertility, miscarriages, short stature and intestinal cancers from consuming gluten.

Andrea Levario, executive director of the American Celiac Disease Alliance in Alexandria, Va, has a son with celiac disease. She told USA Today that she thinks the new FDA rules are "fantastic," because as of right now, "If I pick up a product and it says 'gluten free' I don't know what that means because there's no federal standard."

"While a diabetic needs insulin to survive, a celiac must have gluten-free food," Levario said. "Without clear ingredient information and a definitive labeling standard, celiac consumers are playing Russian roulette when it comes to making safe food choices."

In order to keep food companies in compliance with the new rules on keeping gluten free products truly "gluten free," the FDA can seize products that have gluten levels above the legal limit or require companies to recall them, though Taylor doubted it would be necessary, as he expects companies to comply.

"We don't think compliance will be a problem," he told the New York Times. "Industry wants this rule. They have huge incentive to comply with it. They want people to be confident."

"We are thrilled by the FDA's decision to regulate gluten-free labeling," T.J. McIntyre, general Manager for Boulder Brands, which makes Glutino gluten-free products, told USA Today. "This is bigger than products or brands, this is a consumer safety issue."