Why Is 20ppm Of Gluten The Safe Level For Celiacs?

Gluten Free

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..

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  • So they based our safety on one study of 49 adults? Or am I reading that wrong?? If the only treatment for celiac disease is a completely gluten-free diet, why establish any minimum? Why shouldn’t the minimum be zero?

  • I’ve added a little clarification above but yes, the only current randomized study that I’m familiar with is that of Catassi.

    I’m not sure that it’s possible to test for zero gluten but I could be wrong. This is something I wondered about before but I think it is possible to test for no detectable gluten, which I think means <5ppm.

    If Catassi's study is correct 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 so many 20ppm containing foods before ever reaching levels of 10mg of gluten, which have shown to be safe for celiacs. On the other hand, if his results aren't representative of the general celiac population then if still leaves us in a position of not knowing what's safe.

    The best way to tell if 20ppm works for you is probably to have follow-up tests once you are only eating products containing <20ppm to see what you're blood results say. In my case, all went back to normal within a year of eating gluten-free, and at that time I was eating food in the UK deemed as gluten free by the Codex standard of 20ppm.

    4 years on and I don't eat much processed food at all. At least 80% of my diet is natural food and I think this is the best way to limit the gluten levels we consume. If a law were passed making 0ppm the gold standard, it's likely that only naturally gluten free foods would make it under those levels anyway.

    If anyone knows of other research on this topic I'm sure we would all love to hear about it!

  • I’m not comfortable with having any gluten in my food. I’ve never understood that 20ppm either. A study on only 49 adults is not good enough and for me and others to take gluten-free seriously…..gluten-free should mean 0 ppm.

  • The minimum can’t be zero and gluten-free should not mean 0ppm because not only can such a level not be accurately tested, it’s probably virtually unachievable.

    The stricter the standard, the tougher for GF producers to meet the standard. Result – prices go up / producers stop producing. There’s a margin of error in gluten testing methods, which means that in practice producers need to aim for well below 20ppm in order to be sure that they pass any tests: 8ppm-12ppm is typical, I understand.

    I know it seems counterintuitive that gluten is allowed in a ‘gluten free’ product but there is a precedent: alcohol free produce can contain a certain amount of alcohol, sugar free drinks can contain a tiny bit of sugar. Ditto calorie free. There has to be an achievable level.

    Can you imagine all the product recalls of products were 1ppm to be found in 0ppm products during spot checks? The industry would descend into chaos.

    I agree that there is a need for more research, though.

  • Thanks for commenting, Alex, and I completely agree. I do look forward to more research on this, however.

    The only products I eat which aren’t naturally gluten-free as those made in a gluten-free facility or Certified gluten-free and as far as these products go I have no issues. I feel comfortable having 20ppm as the gold standard, until research proves differently.

    In saying this, I think that celiacs should keep their diet as naturally gluten-free as possible rather than eating these 20ppm products all day long. This way there is absolutely no way that you would reach anywhere near the 10mg of gluten level.

  • I would be curious if any medications or comorbidities (other diseases a persona can have as well as Celiac) can cause an increased absorption of gluten in a food or a decreased excretion of gluten from the body. Hum…

  • No Gluten Here

    Mar 23rd, 2013

    One would have to be very careful as 20ppm can potentially be in ONE serving size on the package, so if it says 10 crackers, it means 10 crackers. Then if you go on to eat another processed food and again eat ONE serving size, does that mean you can now be up to 40ppm on a single day? This is how I figure, and many of the reasons people with celiac can’t get better. The law should be no greater than 5ppm per any product, but companies should aim for zero!

  • I personally think the tolerance level can vary from person to person. I have several people in the support group that I run who feel certain they cannot tolerate even 10ppm.

  • I know that my son and I have reacted to products that are tested to less than 20 ppm. Other people I know have reacted, too. But clearly, not everyone is that sensitive. I wish that the US would adopt a lower standard, but at this point, having any standard is better than nothing. Thanks for a great, informative post!

  • eyeseeglutenfree

    Oct 8th, 2013

    5.6mg is about a teaspoon. If I ate A teaspoon of pure gluten. I would be extremely sick for two weeks with Intestinal pain, cramps, diarrhea, nausea. Then I would feel bad for months afterwards. Just think of gluten as rat poison. How much rat poison do you want your children to eat? For someone diagnosed with Celiac Disease, The question should not be how much gluten can I eat?, It should be how can I eat gluten free food?. Free should mean 100% free.
    Someone needs to develop a test to determine that there is no gluten. The lowest test is >5ppm. Reputable companies that have gluten free facilities and never process gluten in their factories. I have personally reacted to >20ppm in so called gluten free food. The few companies that have food that does not make me sick use >5ppm test. i.e. SHAR and UDIS brands. I believe that the USA government did not consider people at all when using this >20ppm figure. They considered the companies making the products. If these companies had to modify the manufacturing practices to accommodate >5ppm, then it would be extremely expensive, and cut into profits. The manufacturing equipment cannot be cleaned sufficiently if it is shared with gluten containing ingredients. The gluten sticks too tightly to the machinery. Thus the need for allowing gluten in the items.

  • Rebecca

    Jul 25th, 2014

    I am a seriously senstitive celiac now that I have been off gluten for 9 years. I used to just get diarrhea and gas pains and terrible stomach pain, but now if I get something contaminated I have unbearable nausea, vomiting, diarrhea, sweating and sometimes fever and inability to stay conscious b/c of my blood pressure dropping d/t the vomiting. In any case, I do a lot to avoid gluten. However, I think if something says it is GF it should be measured to be below 20 ppm. It makes sense to limit processed/created foods versus foods like fruits, veggies and proteins that are just gluten free naturally. HOWEVER, having said that, the think I resent the most about having celiac and being GF is the public perception that the GF diet is annoying or some kind of neurotic affectation. I am not sure we do our fellow celiacs any favors by splitting hairs about PPM. YES, I want to be healthy and well and I need to stay GF but we need to also work on accepting science and testing. Having said that, there are immoral companies out there who are looking to label their products gluten free when no testing or certification has been done. For example, Shakeology. They claim their mixes are gluten free, but they list wheat grass barley grass etc as ingredients, and you can bet some of those grasses have seeds and protein molecules in them either thru the grasses or the manufacturing of the product. Does ANY celiac want to drink something that was harvested in a wheat grass field!? I tried Shakeology, when I ready that it was GF on their website, and was horribly sick. I called the company and they said they are working on getting it certified GF but right now they just believe it to be GF. This is ridiculous, and NO company should be able to state their food is GF if it just ISN’T. I just wish we could be stronger, more firm and sure, united with clear parameters, so the education can be out there with the manufacturers and wait staff and restaurants and food trucks and EVERYONE.

  • Dietitian

    Sep 22nd, 2014

    20 ppm cut off for gluten free is definitely not a safe level for Coeliacs. Why you ask??
    The “U.S. 2011 Food and Drug Authority Health Hazard Assessment for Gluten Exposure in individuals with Coeliac Disease: Determination of Tolerable Daily Intake Levels and Levels of Concern for Gluten” states that a less than 1 PPM level of gluten in foods is the level of exposure for individuals with CD on a GF diet that protects the most sensitive individuals with CD and thus, also protects the most number of individuals with CD from experiencing any detrimental health effects from extended to long term exposure to gluten. It is therefore hard to understand why the US would set the level at 20 ppm given this evidence but I understand that it was based on testing not safety reasons. Safety should come first. Examining the Cattasi 2007 study (American Journal of Clinical Nutrition 2007. Volume 85:Pages 160-165) carefully also shows that 10 mg gluten per day (= 20ppm of 500g of GF food) resulted in up to half of those patients deveoping worse changes in their gut. Australia has the lowest level of GF (no detectable gluten = approx <3 PPM) and for my health's sake I hope it stays that way.

  • Stephanie

    Oct 2nd, 2014

    In addition, with the 2007 Catassi study: “One patient (challenged with 10 mg gluten) developed a clinical relapse.”

    Of the 26 test subjects, one developed a clinical relapse.
    How that was considered safe is beyond my understanding.

  • I agree that 0 ppm might not be reasonable from a business perspective – but our health is not a business! I react to waaay less than 20ppm in a way that negatively affects my productivity at work. When companies allow products I know and love to be called GF even though they ADD gluten ingredients as “natural flavors” or they KNOW that cross contamination exists, I simply feel violated. Can’t we just have a better labeling system? Instead of having to contact every company individually and listen to them give unclear answers because they don’t want to lose business, they could just tell us “GF<20ppm, Possible CC, or Produced in GF Facility". The only solution I have found so far is a whole foods diet…I never thought I would be forced into this position.

  • I just wanted to clarify, in reference to eyeseeglutenfree’s comment, that one teaspoon of flour is about 2.52 grams, and not 5.6 milligrams. 10 milligrams of gluten would be about 1/252 of a teaspoon, that is, there would be 252 doses of gluten on one teaspoon. In other words, you’d be having a teaspoon of gluten every 8 months or so.

  • Sharon

    Apr 8th, 2015

    I just consumed a medium bag of Smart Food Cheddar popcorn. 3 hours later, I had a reaction. The bag says it is GF, however the website says it is based on the 20ppm. Everything else I ate today was GF. It must have been the popcorn. Maybe I am just one of the really intolerant celiacs.

  • I have dermatitis herpetiformis. I am in my third year of dealing with this. I recently went 4 weeks with out a breakout. I do take Dapsone also. I have become so sensitive to gluten I have a reaction if I use toilet paper that uses wheat flour instead of corn flower between the layers of paper. I can go on and on. Makeup, shampoo and conditioner, clothes and dish soap, vitamin e, caramel flavor and coloring. In three years I have only been 4 weeks in row and it was just recently.
    I am not sure if you are familar with dermatitis herpaformis but the rash/sores itch so bad you want to dig them out with a grapefruit spood.
    I recently learned about the 20ppm and it is called gluten free. I wonder if this is where some of my problems comes from. I think gluten free should just be that. Gluten Free

  • I notice 20 parts per million instantly, or, within
    10mins. I have called all companies that I buy
    from and the same reply, it is gluten free and
    hang up. I cannot have any chips of any
    kind now. The Big Question, is fda patrolling
    the factories where these products are being
    produced. Called fda and was told companies
    are checked every 2 or 3 years!!!!!!!!!!!!!!!!