Gluten is a protein found in wheat, rye and barley, and folks with NCGS report a wide range of symptoms from eating gluten containing foods despite not having celiac disease or a wheat allergy.
There is no reliable test for NCGS so most cases are self-diagnosed based on symptoms improving on a gluten free diet.
To study if gluten is indeed at fault, a group of NCGS experts recommend using a double-blind, placebo-controlled (DBPC), cross-over gluten challenge as the gold standard for identifying NCGS.
Here’s what that might look like:
- Identify participants who show at least a 30% reduction in GI symptoms after six weeks on a gluten free diet.
- Participants receive a daily dose of gluten or gluten free placebo for a predetermined amount of time without researchers or participants knowing what was given.
- Participants resume their prestudy gluten free diet without gluten or placebo for at least one week (wash out period).
- Participants receive a daily dose of gluten or gluten free placebo, whichever they did not receive earlier, for a predetermined amount of time.
- Participants record their symptoms throughout.
- If symptoms are triggered by gluten but not by gluten free placebo then the participant is determined to have NCGS.
A recent review article analyzed data from ten studies to determine the accuracy of the DBPC design for determining NCGS.
The researchers discovered that more than 80% of 1,312 adults with self-reported NCGS did not meet the diagnostic criteria for NCGS after completing a DBPC gluten challenge. These patients reported similar or worse symptoms with the gluten free placebo compared with gluten or they experienced no symptoms with gluten or placebo.
These findings imply that gluten may not be responsible for symptoms in the majority of patients with self-diagnosed NCGS. They also question the accuracy of a DBPC gluten challenge for diagnosing NCGS and stress the need for consistency across study protocols in regards to challenge and wash-out duration, gluten dose and placebo selection.
Though less than 20% of participants showed gluten-specific symptoms, the majority of patients did feel worse after eating gluten or wheat, but the entire blame cannot be placed on gluten.
Gluten is one of many proteins in wheat. Two other proteins include amylase-trypsin inhibitors (ATIs) and wheat germ agglutinin. ATIs activate the immune system and might produce symptoms in NCGS patients with autoimmune or allergic diseases. Laboratory studies have linked wheat germ agglutinin to epithelial-damage and immune system activation.
In addition to proteins, wheat contains highly gas-producing carbohydrates known as fructans, a type of FODMAP. FODMAPs are well known for causing uncomfortable gas, bloating, diarrhea and constipation in people with IBS or small intestinal bacterial overgrowth.
None of these facts discount the reality that up to 13% of the Western population feels better on a gluten free diet. But, they do emphasize the need for more research into the strange world of NCGS, a better diagnostic tool for NCGS, and a more accurate label for this complex condition.