According to Mintel’s Global New Products Database, the number of new gluten-free products introduced in the United States increased from about 135 in 2003 to 832 in 2008. And gluten-free product sales are expected to grow at a rate of 25% annually for the next several years.

Gluten refers to a naturally occurring, specific complex of proteins found in grains. A 33-amino acid peptide molecule, gluten is not fully digested by some people. Intolerance to peptides that remain following partial digestion elicits an immune response that may lead to an onset of clinical manifestations resulting in a possible diagnosis of celiac disease (CD). Approximately three million people, or 1% of the population, have been diagnosed with CD; this figure may be conservative, however.

CD is not curable; however, once gluten is removed from the diet, most individuals experience remission and can reduce the health risks associated with CD. Diagnosis may be challenging due to the number and variable penetrance of symptoms. A strong genetic predisposition exists, with the human major histocompatibility complex molecules DQ2 and DQ8 being necessary for the development of CD. The presence of these human leukocyte antigen (HLA) haplotypes provides up to 40% of the genetic risk. Research conducted on infants with CD has indicated that environmental factors—including lack of breastfeeding, large amounts of gluten in some European infant formulas, and having more than three infections—can contribute to the development of the disease.

Once gluten protein interacts with HLA molecules, an abnormal mucosal immune response occurs, resulting in atrophy to the intestinal villi, fingerlike projections in the small intestine that aid in absorption of nutrients. Individuals with type 1 Diabetes Mellitus and Down syndrome have a prevalence of CD up to 8% and 12%, respectively. Just recently, researchers found that those with CD had greater than a fourfold increased risk of hypothyroidism, a threefold increased risk of hyperthyroidism, and a 3.6-fold increased risk of thyroiditis. The reverse was also true at a statistically significant level for an increased risk of CD with those specific conditions of the thyroid. Researchers believe the associations may be due to shared genetic or immunological traits (Elfström et al., 2008). A gluten-free diet has become a diet of choice as a nontraditional treatment for autistic children although little reliable research supports this association.

In general, caution must be taken in recommending a gluten-free diet because it can pose challenges for nutritional adequacy. Hallert et al. (2002) assessed the nutritional status of 30 adults with CD in biopsy-proven remission who followed a gluten-free diet for 10 years. The researchers found the levels of folate, B-6, and B-12 were significantly lower in patients following a gluten-free diet. Nutritional care is advised to those following a gluten-free diet to ensure that nutrient intake is adequate.

In January 2007, the FDA released the proposed rule for labeling gluten-free products. Under the proposed ruling, the term "gluten-free" is voluntary, and a product that contains no gluten does not need to state this fact. Gluten-free is defined as "containing less than 20 ppm of gluten." For labeling purposes, gluten-free also means the food does not contain any of the following: an ingredient that contains any species of prohibited grains (wheat, rye, barley, or a crossbred hybrid of these grains); an ingredient that is derived from a prohibited grain and has not been processed to remove the gluten (e.g., wheat flour); an ingredient that is derived from a prohibited grain but has been processed to remove gluten, if the use of that ingredient results in the presence of 20 ppm or more gluten; or 20 ppm or more gluten. If a product that claims gluten-free does not meet the above criteria, the product would be considered "misbranded." FDA states that determination of compliance does not need to be based strictly on analysis of food, but can also be assessed based on label review and inspections of manufacturing sites.

As the science behind gluten continues to evolve, the popularity of gluten-free diets continues to grow. Manufacturers need to understand the complexity of CD and/or gluten sensitivity in order to deliver healthy, delicious products to meet consumers’ needs.

References for the studies cited above are available from the authors.

by Roger Clemens, Dr.P.H.,
Contributing Editor
Scientific Advisor, ETHorn, La Mirada, Calif.
[email protected]

by Joy Dubost, Ph.D., R.D.,
Contributing Editor
IFT Food Science Communicator
[email protected]