Gluten-free diets are increasing in popularity, and some would even say that it’s become the latest fad diet, soon to pass out of style. While this may be true for some gluten-free dieters, for those with Celiac Disease or Gluten Sensitivity, a gluten-free diet is necessary for quality of life. Researchers are realizing that negative reactions to gluten in the body are far-reaching. So far-reaching, in fact, that reactions to gluten not only cause inflammation, chronic digestive issues, and pain but are increasingly linked to psychological disorders such as autism spectrum disorders, schizophrenia, hyperactivity, and mood disorders, including bipolar disorder, depression, and anxiety.
How does a generally non-toxic food produce such harmful effects?
While wheat and gluten (the general name for the type of proteins found in wheat, rye, barley, and other grains) does not cause adverse effects in most people, for some it can cause reactions that are profoundly harmful (1). For those genetically predisposed to Celiac Disease, gluten builds up in the small intestine and triggers an immune response. The body mistakenly responds to this inflammation by attacking the cells of the small intestine rather than the cells of the undigested gluten. This results in the breakdown of the tight junctions that keep the intestinal lining strong and healthy, resulting in inflammation and unwanted intestinal permeability (2).
For those without Celiac Disease but who still find themselves to have a Gluten Sensitivity, the cause of damage from gluten-containing foods is less easily proven (there is much debate between whether it is the gluten protein itself or if it is because grains containing gluten are high in FODMAPs (3)). Nonetheless, the cycle of destruction is similar. The tight junctions that hold the cells of the intestinal lining together are loosened, allowing partially digested gluten to get through the lining and into the bloodstream. Immune cells find the rogue gluten (and often other bacteria that provoke the immune system) and react, creating gluten-related antibodies and the same cycle of ever-increasing inflammation and intestinal permeability (3, 4).
This damage leads to the symptoms most often contributed to Celiac Disease and Gluten Sensitivity, such as gastrointestinal distress, fatigue, other autoimmune diseases, pain, and chronic inflammation among others. Chronic inflammation is a cause of many body-wide issues and is the potential link between intolerance to gluten and mental health disorders (5,6).
Effects of Gluten on those with Autism Spectrum Disorders
GI symptoms such as chronic diarrhea, constipation, and bloating have long been known to be comorbid conditions with autism spectrum disorders (7). Interestingly, children with autism have also been shown to have increased immune reactivity to gluten, otherwise known as Gluten Sensitivity (8). Multiple studies have been done to study the potential connection between gluten, gastrointestinal symptoms, and those with autism spectrum disorders, and have shown a correlation between observing a gluten-free diet and a decrease in GI symptoms (9). Beyond that, those on a gluten-free diet also showed a significant increase in not only absorption of vitamins and minerals, but even improvement in symptoms of autism such as increased eye contact, learning skills, sociality, and overall development (9, 10).
Schizophrenia, Inflammation, and Gluten
Studies on the association between schizophrenia and wheat/gluten first began during WWII, when rates of wheat consumption and schizophrenia both decreased in Scandinavia, but simultaneously increased in the United States. Studies of other populations that traditionally had little or no grain consumption and almost no instances of schizophrenia continued this connection, as records of patients with schizophrenia increased with westernization and grain consumption to eventually become on par with European rates (11).
Furthermore, studies have shown that many people with schizophrenia have high levels of inflammation and that many of these people find marked relief from adhering to a gluten-free diet (11, 12). Benefits include improvements in gastrointestinal adverse effects, attention, overall function, and decreased symptom severity (11). Because this adverse reaction to gluten can be screened for by the level of gluten-related antibodies in the blood, this opens up a pathway to earlier detection of schizophrenia, as well as a potential early treatment to curb the development of severe psychotic symptoms (6, 11, 12).
Mood Disorders, Hyperactivity, Celiac Disease, and Gluten Sensitivity
Mood disorders, such as bipolar disorder, major depressive disorder, and anxiety disorders including panic disorder are strongly associated with Celiac Disease, with bipolar disorder being 17 times more likely to affect those with Celiac Disease than the general population (13). Other studies support the connection between gluten and mood disorders in those without Celiac Disease who are sensitive or intolerant to gluten (13, 14).
Interestingly, because Celiac Disease has a lack of classical symptoms, it is considered to be under- or misdiagnosed. Gluten Sensitivity, which is now being recognized as a unique disorder, is considered to be the same. This means that some cases of depression, panic, or other mood disorders may actually be caused by an undiagnosed gluten-related disorder (14).
Furthering this link is the discovery that some people who have been diagnosed with bipolar disorder but not Celiac Disease have a distinct reaction to gluten (unusual levels of protein absorption, inflammation, and high antibody levels) that is similar to the reaction that occurs in people who have schizophrenia (15). This reaction by the immune system can create gluten-related antibodies and is found to occur not only in those suffering from bipolar disorder, but depression, anxiety, mania, social phobias, and hyperactivity (14, 16). This creates a case for a bidirectional relationship between Celiac Disease/Gluten Sensitivity and mood disorders, which suggests that a gluten-free diet could be a plausible treatment option to improve mood disorder symptoms (14). For cases of anxiety and hyperactivity, studies have shown significant improvement after 1 year of a gluten-free diet, highlighting the potential underdiagnosis of gluten-related disorders in conjunction with mood and attention disorders (6 17).
Functional Medicine to Address Gluten-Related Disorders
While a gluten intolerance is not always the cause of the symptoms and disorders mentioned above, if you are not feeling well, it is absolutely worth discussing with a physician. Reactions to gluten can cause many other physical and mental problems not listed above that may manifest in surprising and unpleasant ways. While Celiac Disease can be easily tested for, Gluten Sensitivity is not always able to be determined by an antibody test. This creates a need for a holistic approach to medicine to determine whether a reaction to gluten exists and if it is causing other symptoms or disorders. These types of complex issues are where functional medicine, which focuses on identifying the root cause of many symptoms, can shine.
Functional medicine,