I've heard a lot of hype lately about Non-Celiac Gluten Sensitivity and seeing people buy plenty of "Gluten-Free" goodies at the local grocery store, I am wondering. Is Non-Celiac Gluten Sensitivity an actual illness or just another trendy diet?
Because the condition is so variable and widely thought to be underdiagnosed, it's a little of both, actually.
And the term "non-celiac sensitivity" usually refers to sub-clinical cases of Celiac where the symptoms are present, but not of such a nature that the patient ever seeks medical attention regarding them.
First, what is Celiac?
Celiac disease (CD) is an immune-mediated disease of the intestines that is triggered by the ingestion of gluten in genetically susceptible individuals. Gluten is the major protein component of wheat, rye, and barley. source (medscape link)
Basically, the condition can be explained as:
- The susceptible person ingests gluten
- The body's immunologic response goes haywire, because it identifies the protein on the wheat gluten (usually gliadin) as "foreign" and attacks.
- The intestinal mucosa is damaged in the cross-fire.
- The damaged mucosa is no longer able to function properly and as a result will not properly absorb nutrients until it is repaired.
Current research is indicating a possible genetic link....
Genetic predisposition plays a key role in CD and considerable progress has been made recently in identifying genes that are responsible for CD predisposition. It is well known that CD is strongly associated with specific HLA class II genes known as HLA-DQ2 and HLA-DQ8 located on chromosome 6p21. source (medscape link)
The signs and symptoms a person with this condition will manifest are dependent on many things, such as the length of intestine involved, and age.
In infants Celiac can be life-threatening or cause permanent sequelae such as growth and developmental delays, weakness and muscle wasting.
In older children gastrointestinal symptoms are often seen, such as abdominal pain, diarrhea, dyspepsia, flatulence and weight loss.
In adults the condition is less likely to be life-threatening and are often vague or non-specific symptoms such as impaired fertility, fatigue, depression, anemia, and sometimes short stature. Adults are more likely to manifest these symptoms than the digestive symptoms displayed in younger patients with celiac. The symptoms exhibit this wide range and variety of presentations because they often co-present with the symptoms of malabsorbtion caused by the damage done, which is dependent on the amount of intestine the disease has damaged.
Also relevant is the fact that up to 40% of patients who have been diagnosed serologically (In the US, serologic tests are usually IgA endomysial Antibody Test and IgA tTG antibody test which have >90% sensitivity and a >95% specificity for celiac, so they are fairly reliable. There are also other tests available, though) for celiac have the "silent" form of the condition, in which there are little to no symptoms present. The reason for this remains unclear (This comes directly from Current Medical Diagnosis & Treatment, but the one my shelf, sorry).
Those who may have a "silent" or sub-clinical(sometimes referred to as "Non-Celiac sensitivity popularly, but not by the medical community) case of Celiac will of course benefit from reducing, if not eliminating gluten from the diet. However, true elimination of gluten exposure is extremely difficult, as it is in practically everything, not merely food products, but many medications, some glues, such as one used in certain brands of cigarettes (I know, yet another reason not to smoke).
Even though attempts at self diagnosis are almost always unwise even for trained medical professionals, if a person perhaps has a family history of the disease or a strong reason to suspect they might be experiencing a reaction to gluten, certainly a trial of a gluten free diet for a period of time is a relatively safe way to see if improvement occurs. However there are certain comorbidities with celiac disease that should be looked into by a physician, such as diabetes, osteoporosis, increased risk for certain cancers, if you think you actually do have celiac.
And now for the fads....
The main "selling point" for the gluten-free diet is the reported under-diagnosing of celiac (at least in the US). As Harvard Health reminds us:
Celiac specialists say the disease isn’t diagnosed as often as it should be. As a result, many people suffer with it for years, often after getting other — and incorrect — diagnoses and useless treatments
This leaves much room for people to peddle the gluten-free diet. Especially if those selling the plans and products can convince you that you are in that 40% mentioned above who may have "silent" or sub-clinical celiac. Also, since there are virtually no documented side effects of an otherwise healthy person adopting a gluten-free diet, there's the added selling point of the "what's the harm?" argument. However, just because there aren't many documented adverse effects does not mean there are benefits, and even most of the advocates for the diet make vague and weak arguments as to the benefits of a gluten free diet a healthy individual, sometimes relying on the "common sense" argument that people adhering to a gluten-free diet would also be avoiding many of the most common fried and fattening foods.
Basing your diet off of the gluten-free phenomenon can be genuinely healthy and may benefit your cholesterol levels, digestion, and energy level. You don’t have to worry about the little things like soy sauce and malt flavorings, but if you avoid the major red flags in the gluten-free diet, you just might start to feel healthier. For example, you would have to avoid everything that’s fried because of the breading, which would allow you to avoid the oil and fat, as well. source
Another argument which falls on the side of those selling the gluten-free diet is that there has been at least one study done indicating that the higher cost and lower availability of gluten-free products is one of the chief factors for non-compliance in diagnosed celiac patients, and an increase in the popularity and availability of gluten-free products may help this.
Conclusions: There is limited availability of gluten-free foods and they are generally more expensive than their standard counterparts. This may impact on compliance to a gluten-free diet, with potential nutritional and clinical consequences, together with an increased risk of complications.
There has been some study done into how gluten metabolism affects the natural bacterial activity in the intestines, such as this
The activity of the intestinal microbiota is modified by gluten intake in the diet. The incorporation of gluten in the diet increases the activity of a gluten proteolytic activity in the faeces
but however, there is no proven practical application for this finding, as far as I know. And there have been no documented instances of benefits for non-celiac patients adopting the gluten-free diet, even though there has been some mention of a weak correlation with lower cholesterol levels.
In the end, it's not likely to harm you. But then again, it's probably not likely to help you, unless you actually are in that 40% of "silent" celiac cases.
The best evidence we currently have suggests that NCGS is probably not a real entity. (Steven Novella - Neurologicablog)
This is based on a 2013 study that concluded:
In a placebo-controlled, cross-over rechallenge study, we found no evidence of specific or dose-dependent effects of gluten in patients with NCGS (non-celiac gluten sensitivity) placed diets low in FODMAPs (fermentable, oligo-, di-, monosaccharides, and polyols).
This suggests that NCGS is not a real clinical entity, and that those that have self-diagnosed are either borderline celiac, subject to noncebo effects and confirmation bias, or experiencing symptoms due to some other food exposure, with FODMAPs being one possibility.
This result seems to conflict with the same group's 2011 result. They discuss this at length in the 2013 report.
Several key differences in study design might have potentially influenced the results. First, in contrast to the previous use of supplements with the habitual diet, food intake was carefully controlled. All food provided was low in FODMAPs and gluten-free to reduce “background noise” and control for changes in participants’ usual diet, particularly intake of other potential dietary triggers.
The restriction of all dairy products and food chemicals was also employed in the rechallenge trial in order to control other putative triggers of gut and other symptoms.
The third difference was the utilization of a crossover design to reduce the influence of confounders and increase power.
It is possible that the gluten used in the current study was different from that in the first (suppliers were different). The gluten content was similar, but the non-gluten proteins were not characterized.
Alternatively, gluten might induce symptoms only in the presence of a moderate content of FODMAPs.
Non-celiac Gluten/Wheat Sensitivity is a named, studied, consensus formaly approved real condition.
It is at the same time one of many temporary trendy diets chosen by un-informed crowds on their own behalf and with no scientific evidence nor will to accumulate some, and as a consequence this condition is often self-mis-attributed.
DETAILLED AND REFERENCED ANSWER
Well, it's not "just another trendy diet":
NCGS or NCWS (non-celiac gluten/wheat sensitivity) is also a trendy topic for scientists mainly since 2010, covered with large number of papers (461 on Google Scholars at the time of this writing) including:
- numerous papers published in the highest impact journals of their discipline. For instance, it has 30 publications since 2010 on Gastroenterology, the highest Scientific Journal Ranking on gastroenterology
- meta-analysis and review papers published in highly recommendable journals as the Lancet Neuro: "From Guts to Brain" in 2010, or "Non-Coeliac Gluten Sensitivity" in late 2014
- consensus papers and meetings for inclusion in nomenclature signed/attended panels of experts in:
- Meeting London 2011 - Full article: London February 2012 - Spectrum of gluten-related disorders: consensus on new nomenclature and classification,
- Meeting December 2012 - Full article: Munich December 2012 - Non-Celiac Gluten Sensitivity: The New Frontier of Gluten Related Disorders
But it's of course undeniable that it is also a trendy diet. If it was necessary backup, a study suggest that as much as 86% of the people that perceive themselves as having NCGS didn't have any disorder related to gluten... but it is only one study... and you shouldn't give much credit to only one paper of one study. However, the fact that it's a trendy diet does not seem to be the subject of your question. So let's move on to your real question as I understood it:
Is Non-Celiac Gluten/Wheat Sensitivity an actual illness ?
As a matter of fact, being under scientific scrutiny does not imply that this is a real condition: a substantial number of these article dispute the actual status of NCGS or asks for clarifications around it, added to that, there are still numerous incoherent/negative results in various papers. Although, there is an undebatable scientific consensus (per say, a paper signed each year by 40+ domain's experts they call "consensus") to state that it is a condition, although a lot is left to know about important (crucial?) details:
is gluten the real cause of these symptoms ? (probably not)
what are the underlying mecanisms involved ?
what biological markers could help diagnose it ?
prevalence of this condition in the population ?
However, depending of your definition of "actual illness", the answer may vary. NCGS is becoming de-facto a recognised condition by medical research and progressively clinics around the world through the repeated consensus meetings/papers and numerous short review papers/notices intended for internal physicians and clinicians. But it's undeniable that it stills suffers of the lack of direct strong ground evidences.
As a conclusion, let me quote the abstract of "Non-Coeliac Gluten Sensitivity" Article 2014:
[...] Although there is clearly a fad component to the popularity of the Gluten Free Diet, there is also undisputable and increasing evidence for NCGS. However, we require a better understanding of the clinical presentation of NCGS, as well as its pathogenesis, epidemiology, management, and role in conditions such as irritable bowel syndrome, chronic fatigue, and autoimmunity [...]
More about NCGS/NCWS ?
BTW, clinical papers are a good way to get a straight-to-the-point short review of what NCGS/NCWS is (without too much of scientific jargon), and if you are interested about knowing more about it, here's one: September 2015 - Mayo Clinic
I was quite impressed by the coverage done on about.com on gluten intolerance. It does a pretty good job of summing up accurate and carefully backed up recent knowledge about NCGS/NCWS. This is the most readable digest you'll get on science status of NCGS/NCWS.
As it was requested in comments, here's some consistent knowledge around NCGS/NCWS, found in the many review documents:
- NCGS/NCWS symptoms can be gastrointestinal and/or extraintestinal
- The prevalence is unknown
- It has features that overlap with those of celiac disease and wheat allergy
- It's pathophysiologic process is thought to be an innate immune mechanism
- Dietary triggers other than gluten, such as the fermentable oligosaccharides, di- saccharides, monosaccharides, and polyols, have been implicated.
- no clinical biomarker was found yet to diagnose NCGS
- exclusion of Coeliac Disease and Wheat Allergy is necessary in the evaluation of a NCGS case
- NGCS symptoms typically disappear when wheat is removed from diet.
- Wheat elimination diet followed by a monitored open challenge of wheat intake to document recurrence of symptoms can be helpful.
- onset of NGCS/NCWS's symptoms can occur within hours or days of wheat ingestion.
EDIT: Sorry about that, but my google scholars initial research was bogus due to a bad name collision. I corrected it.
At least one study found that there was a placebo-controlled reaction to BREAD (sliced bread, muffins) in a non-Celiac group: http://www.ncbi.nlm.nih.gov/pubmed/21224837
OBJECTIVES: Despite increased prescription of a gluten-free diet for gastrointestinal symptoms in individuals who do not have celiac disease, there is minimal evidence that suggests that gluten is a trigger. The aims of this study were to determine whether gluten ingestion can induce symptoms in non-celiac individuals and to examine the mechanism.
METHODS:A double-blind, randomized, placebo-controlled rechallenge trial was undertaken in patients with irritable bowel syndrome in whom celiac disease was excluded and who were symptomatically controlled on a gluten-free diet. Participants received either gluten or placebo in the form of two bread slices plus one muffin per day with a gluten-free diet for up to 6 weeks. Symptoms were evaluated using a visual analog scale and markers of intestinal inflammation, injury, and immune activation were monitored.
RESULTS: A total of 34 patients (aged 29-59 years, 4 men) completed the study as per protocol. Overall, 56% had human leukocyte antigen (HLA)-DQ2 and/or HLA-DQ8. Adherence to diet and supplements was very high. Of 19 patients (68%) in the gluten group, 13 reported that symptoms were not adequately controlled compared with 6 of 15 (40%) on placebo (P=0.0001; generalized estimating equation). On a visual analog scale, patients were significantly worse with gluten within 1 week for overall symptoms (P=0.047), pain (P=0.016), bloating (P=0.031), satisfaction with stool consistency (P=0.024), and tiredness (P=0.001). Anti-gliadin antibodies were not induced. There were no significant changes in fecal lactoferrin, levels of celiac antibodies, highly sensitive C-reactive protein, or intestinal permeability. There were no differences in any end point in individuals with or without DQ2/DQ8.
CONCLUSIONS: "Non-celiac gluten intolerance" may exist, but no clues to the mechanism were elucidated.