Science bite: Gluten-free diet in Irritable Bowel Syndrome
Howdy folks! Apologies for the long interval between Science Bites. Since I’ve taken on a Board of Directors role at Specialty Health, my work volume has really increased, and it’s left me very little time to write. Add to this the fact my mom was in the hospital for nearly three weeks (we almost lost her), and I’ve just been damn busy. Lots of interesting happenings in the ancestral health scene – I’ve talked to three different TV production companies who are interested in exploring this whole concept – so great stuff brewing, just not a lot of spare time!
Ok, that’s my excuse as to my writing hiatus, but now let’s get down to bid-ness.
Today’s Science Bite: Gluten-free diet in Irritable Bowel disease
Today, I’d like to look at a fantastic paper studying the effects of a gluten free diet on folks with IBS. Read the paper here
Study Type: Randomized controlled trial, cross over design, non-metabolic ward, but all foods were either prepared or eaten at the clinic. This does not guarantee that the study participants did not cheat on the plan, but this is an outstanding compromise between trying to ensure exactly what participants ate and minimizing study costs. IMO this is an outstanding study design, and one that should be more broadly utilized.
Number of participants: 43 (only 2 men, which makes sense given the genetic factors associated with autoimmunity, celiac disease and IBS…I’ll get to that later).
Study design: Participants ate either a rice based gluten free (GF) or gluten containing diet (GCD). Cals were set to be isocaloric (no weight loss or gain)
Inclusion criteria: diagnosis of IBS, currently consuming gluten.
Exclusion criteria: Recently consuming a GFD, indications that a GFD has been previously beneficial, diagnosis of celiac disease. This is smart study design in that the researchers were trying to just look at your average person who has no knowledge of GFD’s, and has not tinkered one way or another. Additionally, they tried to control for the overt state of celiac disease, which is notably common in folks with IBD. This is important as many people still ONLY associate problems with gluten to celiac disease.
What the researchers were looking for: Bowel function, transit time, and several indicators of intestinal/colonic barrier status. Additionally, HLA (human leukocyte antigen) screening for the HLA-DQ2 and HLA-DQ8 haplotypes were assessed. I’ll get to the relevance of looking at this later.
Stool frequency: the GFD showed a decreased stool frequency relative to the GCD. This was more pronounced in the HLA-D2/8 positive individuals. This genotype shows a marked increase in autoimmune disease susceptibility AND a decreased susceptibility to gut pathogens. In essence, these people show a more vigorous immune response, which is likely one of the adaptations to living in close proximity to both a large number of humans and animals in a post Foraging life-way. This represents an evolutionary trade-off between enhanced immunity on the one hand, and autoimmune potential on the other. HLA-D2 Positive individuals are very common amongst celiac (95% of celiacs carry this trait if my memory is correct). However, not all HLA-D2 positive individuals develop celiac. But they do seem to be generally more gluten sensitive and show greater reactivity in all of the findings.
The gluten containing diet showed greater intestinal permeability. Several interesting things: This effect was greater, but no limited to the HLA-D2/8 Positive patients. The effects appear to be via an ENTIRELY different mechanism than that which underlies celiac disease. We to not see CD4T-cell activity, nor do we see increased interferon-gamma in this group studied, in stark contrast to classic celiac disease. We do see elements of both the innate and adaptive immune system being activated, but in novel ways relative to CD.
The study authors concede more work needs to be done to see what, if any, effects a GCD vs a GFD might have on gut biome. I like that these folks are thinking in this direction, as the big picture to all this goes beyond just what happens in the interface between immunogenic proteins from grains and our gut. The most important takeaways are clearly that a GFD improves IBD symptoms, decreases stool frequency, and decreases intestinal permeability. When we consider the highly inflammatory processes associated with intestinal permeability (ranging from autoimmune disease, to obesity, to cardiovascular disease, to various cancers), this is a huge “win.” Would we see even better results with an integrated paleo approach, adequate sunshine, probiotics, etc, etc? I would guess “yes”, and as always, what we are suggesting in all this is a safe, easy intervention that could have profound health benefits. If you suffer from GI problems, why not give it a shot?