Media outlets are notoriously awful at interpreting scientific publications. A study done in the UK found that among the top 10 papers there, up to 72% of the dietary advice given in the period surveyed was unsubstantiated or false . So it should not be a surprise that a while back the media bungled yet another publication.
I wanted to comment on the scope and clinical applicability of the following article, No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates, since it has made the rounds on the internet and people continue to misinterpret it.
Since Non-Celiac Gluten Sensitivity (NCGS) does not have a formal clinical diagnosis (yet, it’s being worked on), practitioners have to rely on questionnaires that have patient’s rate things like pain, bloating, stool consistency, nausea, tiredness, and overall symptoms. NCGS is defined as “One or more of a variety of immunological, morphological, or symptomatic manifestations that are precipitated by the ingestion of gluten in individuals in whom Celiac Disease has been excluded” .
This study was designed to find out if “in subjects who report having NCGS, [does] gluten induce dose-dependent, reproducible gastrointestinal and systemic symptoms” .
The 37 subjects selected all had Irritable Bowel Syndrome (IBS) and had self-reported improvement while on a gluten free diet. All were placed on a low FODMAP and gluten-free diet for two weeks and then randomized into one of three groups:
- High gluten
- Low gluten + lactose-free whey protein
- No gluten + lactose-free whey protein
This study contained two parts. During the first portion of the study, participants remained on the above diets for 1 week, followed by a 2-week washout period before crossing over into the next diet. All participants went through all 3 diets for 1 week.
In the second part of the trial, 22 of the original patients were on one of the following three diets for 3 days:
- High gluten
- High lactose-free whey protein
Natural and artificial food chemicals or additives that could potentially trigger symptoms were also excluded. After three days on the diet, they went through a 3-day washout period and were then crossed over into another group.
In addition to assessing symptoms, biomarkers such as serum and fecal markers of intestinal inflammation/injury and immune activation, and indices of fatigue were also measured.
In the first part of the trail, a dose effect of gluten was not observed and gluten specificity of symptomatic responses was observed in only 3 subjects (8%). A dose effect means that as a dose of something increases, you expect to see the symptoms increase with it. In this case, because a dose-response was not observed, it is highly unlikely that gluten alone is a possible trigger for those with IBS.
These results were further confirmed in the second half of the trial when 2 patients that had symptomatic responses to gluten in the first trial did not experience those symptoms while taking gluten in the second trial. In fact, gluten specific symptoms were not reproduced in any subject in the second trial.
Only 1 participant had a positive T-cell response after the high gluten portion of the trial. There were no significant differences in markers of inflammation, immune activation, or fatigue across the treatment periods. “No correlation existed between mean overall symptom score on high-gluten and any of the [bio]markers” .
So what can be drawn from this study? As always, nuance is important. The conclusions I would draw would be to advise those with IBS to talk to a doctor or dietitian about going FODMAP’s free, but I would not tell them that they need to go on a gluten-free diet, although they are welcome to try. The evidence to back such a claim is currently lacking. Future research would need to elucidate on whether gluten is working in combination with other wheat components in inducing GI symptoms in those with IBS, although this paper is a great start. It is one of the better designed, well-controlled trials I have seen looking into the issue of NCGS.
I want to make it clear that this paper does not speak to what gluten will do in an otherwise healthy person nor does it conclude that gluten sensitivity does not exist. It is only looking at the effects of gluten and those with IBS.
When addressing the topic of gluten it is important to note that the best available research shows that the combined prevalence of wheat allergies, Celiacs Disease/Sub-Clinical Celiac Disease, Non-Celiac Gluten Sensitivity/Wheat Sensitivity, dermatitis herpetiformis (DH), and gluten ataxia affect only 10% of the population at the highest estimations [4,5,6]. Gluten often gets scapegoated for a whole host of illnesses, but it’s important to ensure that there is quality science to back up those claims. And please, do not go gluten-free just because Gwyneth Paltrow told you to.
1 - http://www.ncbi.nlm.nih.gov/pubmed/23832153
2 - http://www.ncbi.nlm.nih.gov/pubmed/23648697
3 - http://www.ncbi.nlm.nih.gov/pubmed/22345659
4 - http://www.ncbi.nlm.nih.gov/pubmed/21181303
5 - http://www.ncbi.nlm.nih.gov/pubmed/19122516
6 - http://www.ncbi.nlm.nih.gov/pubmed/17206762