Aug 06 2013

Gluten Free Defined

Gluten is the new food boogeyman for those who want to blame their ills on one simple external factor. The real story of gluten is complex – it is a real problem for some people. The recent explosion of the gluten-free fad has motivated the FDA to establish guidelines for labeling food products as having no gluten. The guidelines were actually proposed during the Bush administration, but it took until now to review the relevant scientific evidence to know where to set the limits.

According to the new regulations:

In addition to limiting the unavoidable presence of gluten to less than 20 ppm, FDA will allow manufacturers to label a food “gluten-free” if the food does not contain any of the following:

– an ingredient that is any type of wheat, rye, barley, or crossbreeds of these grains
– an ingredient derived from these grains and that has not been processed to remove gluten
– an ingredient derived from these grains and that has been processed to remove gluten, if it results in the food containing 20 or more parts per million (ppm) gluten

Foods such as bottled spring water, fruits and vegetables, and eggs can also be labeled “gluten-free” if they inherently don’t have any gluten.

What Is Gluten?

I think the definitive satire on this is from the recent movie, This Is the End. Seth Rogen (playing himself) announces to his friend that he is now eating gluten-free, but when asked what gluten is he clearly has no idea. He says it is anything bad in food. Of course in the next scene he is downing a giant hamburger.

Gluten (meaning “glue”) is a protein found in wheat, barley, and rye. It is composed of two proteins, gliadin and glutenin, which give dough its elasticity and bread its sponginess. Wheat, barley and rye are major crops and therefore gluten is present in many foods – most breads, pasta, and many processed foods.

Meat, dairy, water, fruits and vegetables do not contain any gluten. It’s interesting that the FDA will allow these foods to be labeled gluten-free also. This is a classic example of true but misleading. If a bottle of water is labeled “gluten-free” will this lead some consumers to believe that water not labeled gluten-free might have gluten (why else would they bother to label it “gluten-free”)? Will this lead to a “gluten-free” marketing arms race among food producers?

Celiac Disease and Gluten Sensitivity

Celiac disease is a non-controversial condition in which people have a severe auto-immune reaction to gluten. They have antibodies against gliadin which causes inflammation in their intestines, leading to bloating, diarrhea, nausea, and other symptoms. The reaction to even a tiny amount of gluten can be severe. About 3 million Americans have celiac disease, or 1 in 100 people.

This with celiac disease need to have a diet as free of gluten as possible. You might think that the recent gluten-free fad would be a boon to those with celiac disease, increasing their food choices. However, the lack of regulation has lead to the flooding of the market with products labeled gluten-free that still have some gluten – too much for those with celiac disease. For them the new regulations are clearly necessary.

There is also a highly controversial condition known as non-celiac gluten sensitivity (NCGS) – these are people without celiac disease who believe that gluten causes symptoms of bloating, fatigue, and irritable bowel syndrome symptoms. They do not have antibodies to gliadin.

While clinical anecdotal experience makes it seem like the gluten-free fad is a big thing, the only study I could find estimating its prevalence found that about 0.5% of those surveyed without celiac disease are adhering to a gluten-free diet (that is half the number of those with celiac disease).

NCGS remains controversial because the data so far is preliminary and conflicting. Of the two most recent studies of those with alleged NCGS who were blindly challenged with gluten vs placebo, one study showed no affect and the other did find an effect (both studies were small). Reviews of the evidence are similarly split.

What I think is likely is that there are a number of conditions that are being lumped into the NCGS basket, because it is a high profile diagnosis. These other conditions probably include mild celiac disease that is not being diagnosed, irritable bowel syndrome, wheat allergies, and perhaps other disorders such as chronic anxiety.

There may also be a separate entity of NCGS, but this has not been established either with direct clinical evidence or by finding an underlying mechanism or disease markers.

To establish a new disease it is necessary to have a clear clinical syndrome, with diagnostic features. Migraine is an excellent example of this – there are no markers or diagnostic tests, but the clinical features can be classic and definitive.

Or you need to have a clear biological process, with some laboratory test that indicates the disease process (like antibodies to gliadin).

I am always suspicious of new syndromes that lack both of these things – there are no specific signs or symptoms and no specific biomarkers. NCGS falls into this category. It would therefore not surprise me if NCGS turned out not to exist.

Alternatively it may exist, but only is a subset of those self-diagnosed with the disorder. Overdiagnosis is common with syndromes that lack specific features, especially when there is a high public awareness of them (how would there not be?).


The new FDA regulations (which will be enforced in one year) were absolutely necessary for those who have celiac disease. The downside, however, is that they may contribute to the recent fad in the NCGS diagnosis, which remains scientifically controversial.

What we now need are large definite double-blind trials to clearly establish what percentage of those with self-identified NCGS are actually sensitive to gluten. This won’t make the public controversy go away, but we do have to resolve the genuine scientific controversy before we can hope to educate the public.

I also have to emphasize that doubting the NCGS diagnosis does not represent a lack of compassion for sufferers, nor is it an accusation that their symptoms are all psychological. it is out of compassion that medical practitioners want to have clear diagnoses from which to work. If NCGS is either an illusion, or is being highly overdiagnosed, then those people falsely diagnosed with it are being misdiagnosed. Their true diagnosis is therefore being missed, as is the opportunity to properly treat them.

Also – if we can confidently say that NCGS is a distinct syndrome, then proving it will help future research aimed at figuring out what is causing the disorder.

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