There has been a lot of talk recently about what 20ppm (parts per million) really means. Most countries use the Codex Alimentarius Commission standard of 20ppm as the gold standard for gluten free. As of last week (August 2nd, 2013) the United States have finally defined “gluten free” (Woohoo!!) and the FDA too have decided to go with this rate of 20ppm. There are a few countries which have gone with an even lower level, a level of 10ppm.
But why 20 parts per million? Who decided that 20ppm was a safe level of gluten for celiacs to consume?
There haven’t been many clinical trials to discover the safe level of gluten for celiacs to tolerate. Further trials would require celiacs to consume specific amounts of gluten in order to find out what kind of damage this does. This isn’t something I imagine many celiacs rushing to put themselves down for.
Really the only randomized controlled study which has been done is that of Catassi in 2007. This was a 90 day study involving 49 adults with biopsy-proven celiac disease. Participants were kept to a strict gluten-free diet and could only eat special foods containing less than 20 parts per million of gluten. The effects of participants consuming capsules containing 0, 10 and 50 mg of gluten was then assessed. This is fantastic research but unfortunately the sample size wasn’t very large.
Catassi’s study showed that a daily intake of 10mg of gluten did not cause any intestinal damage. 50mg a day, on the other hand, in most cases was shown to do some harm. This study is also consistent with other studies indicating that a diet containing up to 10mg of gluten per day is safe for celiacs. I couldn’t find any solid information on any of these other studies.
So, how much gluten is 10mg?
Let’s put it this way, for a celiac to reach levels of more than 10mg of gluten per day, they would have to be eating quite a bit more than a pound (more than 500g) of products per day containing 20ppm.
What does 20ppm actually mean? How much gluten is 20ppm?
The Gluten Free Dietician has a great article which explains how much gluten 20ppm is. To break it down, 20 parts per million is the equivalent to 20ppm per kilogram of food. An average slice of gluten-free bread containing 20ppm of gluten would contain 0.57 milligrams of gluten. Even if you ate ten ounces of foods containing 20ppm gluten, that would be just 5.70 mg of gluten. This level is just over half of the 10mg found by Catassi’s study to be a safe level so you would need to eat a whole lot of 20ppm food each day to surpass the “safe” level.
We must also consider that 20ppm is the highest level of gluten that foods can contain to be considered gluten free so most of the products you are eating will contain less than this amount.
Doing the research for and writing this article has cleared up a lot of the questions I had about this 20ppm issue. It has helped me better understand the reasoning behind why 20ppm is widely known as the safe level. This celiac thing can get pretty confusing sometimes!
So what does at all this mean for celiacs? Can celiacs safely eat foods containing less than 20ppm?
To summarize, if Catassi’s study was accurate then celiacs should be able to feel safe eating products which have been verified to contain less than 20ppm of gluten because they would have to eat an insane amount of foods containing 20ppm before ever reaching this level of 10mg of gluten, which has shown to be safe for celiacs.
However, and this is important, how do we know that Catassi’s study was in fact accurate? He only used 49 adults in the study. What if these people and the way their bodies behaved to gluten consumption was not really representative of the majority of the celiac population? In this case, his results wouldn’t really account for much at all.
I recently came across this interesting letter from 2011 which is definitely worth a read - Alessio Fasano M.D. “In Defense of 20 parts per million”. He takes the stance that 20ppm should be the level which defines gluten-free in the US and he explains the many reasons why.
“We believe that establishing a restrictively low threshold of parts per million of gluten will complicate the lives of people with celiac disease and do nothing to improve their levels of safety and comfort. We urge the FDA to establish 20 ppm as the level that defines “gluten-free” in the U.S. marketplace.”
What are your thoughts on all this? Are you comfortable with this level of 20ppm? If not, why not? I’d love to hear your opinions..