What the Experts Are Saying About FDA’s Labeling Proposal
Around the world there are different standards for gluten-free labeling and no doubt there will be differing views of the FDA’s proposal and the scientific basis for its recommendation. Two of our expert members, Dr. Alessio Fasano, Director of the University of Maryland’s Center for Celiac Research, and Dr. Stefano Guandalini, Medical Director of the Celiac Disease Center at the University of Chicago, have shared their perspectives.
In establishing a threshold of gluten to be used in defining “gluten-free foods”, it is evident that our aim should stay focused on identifying what is the highest amount of gluten that would be safe to assume daily for the “vast majority” of individuals with celiac disease. The FDA had 2 routes to follow: either recommending a level based on the lowest amount of gluten considered toxic as reported from published studies and corrected by introducing the 10-fold “uncertainty factor” (the so-called “safety-based approach”); or determining this threshold based on the sensitivity of the best and most reliable testing methods available (the “analytical method” approach).
The agency chose to follow the latter method, and in my opinion this was the right choice. In fact:
The data obtained for the Tolerable Daily Intake (TDI) using the “safety-based” approach show extremely low levels of gluten: this is the result of a rigorous calculations that has these characteristics: a) It takes into account the very few studies where adverse effects were seen at very low concentrations of gluten; and b) it further reduced that amount by a factor of 10 (or in some cases even 100, when only data on the lowest observed adverse effect levels were shown!). Thus, the surprisingly low levels of 0.4 mg/day for “physiological” effects or the incredibly low amount of 0.015mg (15 microgram: an inconceivably minimal trace amount!) resulted as TDI. While this method is formally perfectly correct, its implications are untenable: no one in the celiac community would accept as “intolerable” intakes of gluten in the order of 15 micrograms!
The best methodological tool in clinical investigations is a double-blind, randomized trial. Regrettably, such trials to establish toxicity of gluten in vivo are extremely limited. I would offer that one of the methodologically best studies (noticeably, the only one performed as a randomized controlled study of a microgluten challenge in patients with celiac disease) is the one authored by Catassi et al. in 2007. This study is very clear in indicating that the daily intake of 10 mg of gluten (i.e. an amount 667 times higher than the estimated TDI of 15 micrograms!) for 3 months (!) in known adult celiac patients did not cause any damage, while 50mg/d were in most cases harmful. The gluten threshold identified by the Catassi’s microchallenge study is consistent with a series of studies that have been object of several excellent reviews, concordant in indicating that a diet containing up to 10 mg of gluten per day is safe for celiac patients.
Accepting the analytical method, as well as the indications from the vast majority of studies available has the obvious advantage of allowing to rely on an internationally accepted and well validated method of quantification of the gluten content in foods at level down to 20ppm, and also of conforming the US standards to the European one. And won’t result in any harm to the exceedingly vast majority of celiac patients: in fact, to reach levels of gluten intake above 10mg/day, one would have to ingest more than 1.1 pounds of that product per day. Finally, forcing the manufacturers to produce GF foods with unthinkably low level of gluten would evidently result in a dramatic reduction – and perhaps even a disappearance – of available GF products. In this scenario, everyone can see how celiac individuals would have a much harder time in remaining compliant to the diet.