By now, you’ve likely noticed that grocery stores and restaurants are offering a plethora of gluten-free products and meals.
You might have friends or family members who avoid gluten. Maybe you follow a gluten-free diet, or have been paying closer attention to food labels and avoid it most of the time.
If you don’t know much about gluten, you might wonder why so many people are avoiding it like the plague.
Is the “gluten-free diet” just another trendy health movement, or is there something to this way of eating?
What is gluten, anyway?
Gluten is a complex two-part protein found in grains such as wheat, rye, barley, and spelt. The two different proteins that comprise gluten are called glutelin and gliadin. Breads, cereals, and baked goods are obvious sources of gluten (unless they are labeled gluten-free), but they aren’t the only foods that contain the protein – it can be found in many items, even those you wouldn’t expect.
People who have celiac disease, a chronic autoimmune/inflammatory disorder, must avoid the consumption of gluten. Celiac disease originates in the gut, but affects the entire body when untreated. In people with celiac disease, the villi of the small intestine are damaged when gluten is consumed. When a person with celiac disease continues to eat gluten, serious health problems can develop, including neurological conditions, osteoporosis, other autoimmune disorders – and depression.
Here’s a sampling of studies that have linked celiac disease and depression, as reported by Psychology Today:
Reports of depression among celiac disease patients have appeared as early as the 1980s. In 1982 Swedish researchers reported that “depressive psychopathology is a feature of adult celiac disease and may be a consequence of malabsorption.” A 1998 study confirmed that about one-third of those with celiac disease also suffer from depression. Adolescents with celiac disease also face higher than normal rates of depression. Adolescents with celiac disease have a 31% risk of depression, while only 7% of healthy adolescents face this risk.
The intestinal damage gluten causes in people with celiac disease prevents absorption of essential nutrients that keep the brain healthy, especially zinc, tryptophan, and the B vitamins. These nutrients are necessary for the production of essential chemicals in the brain such as serotonin, a deficiency of which has been linked to depression.
But are people with celiac disease the only ones who should avoid gluten? Are they the only ones who can suffer from health ailments – including mental health issues like anxiety and depression – related to the consumption of gluten?
Some studies suggest it is possible that gluten can affect serotonin levels in people who do not have celiac disease by limiting the availability of its precursor, an amino acid called tryptophan. One study on rats showed that brain serotonin levels decreased after the rats were fed wheat. Whether this occurs in humans, or if this effect still occurs when rats are only fed gluten itself instead of wheat has yet to be determined, but evidence suggests it is possible.
Another possibility is that gluten can cause bacterial imbalances in the gut. Existing research that shows that patients with celiac disease have intestinal dysbiosis, a condition where the bacteria that usually live in a patient are out of balance, and that this condition can be resolved after a gluten-free diet is prescribed. There is already a lot of research in rats that demonstrates the important effects that gut bacteria have on various mental processes, and there is also some evidence showing this extends to humans as well.
Inflammation, Gluten, the Gut, and Depression
We already know that inflammation is the likely cause of a multitude of health conditions, including arthritis, asthma, cancer, chronic pain, headaches, and heart disease.
More and more research suggests an addition to the growing list of ailments with possible links to inflammation: depression.
About 70% of our immune cells are in our digestive system, and they make direct contact every bit of food we consume. If the immune system is triggered by bacteria in food, flags a food as an allergen, or has an imbalance of important hormones such as insulin, it can cause inflammation.
Gut bacteria produce hundreds of neurochemicals that the brain uses to regulate basic physiological processes as well as mental processes such as learning, memory, and mood. Serotonin is a prominent example: while it is well known as a brain neurotransmitter, it is estimated that 95 percent of the body’s serotonin is made in the digestive tract, which influences both mood and gastrointestinal (GI) activity.
As Dr. Siri Carpenter explained in these excerpts from the article That Gut Feeling:
When you consider the gut’s multifaceted ability to communicate with the brain, along with its crucial role in defending the body against the perils of the outside world, “it’s almost unthinkable that the gut is not playing a critical role in mind states,” says gastroenterologist Emeran Mayer, MD, director of the Center for Neurobiology of Stress at the University of California, Los Angeles.
Gut bacteria both produce and respond to the same neurochemicals—such as GABA, serotonin, norepinephrine, dopamine, acetylcholine and melatonin—that the brain uses to regulate mood and cognition. Such neurochemicals probably allow the brain to tune its behavior to the feedback it receives from the army of bacteria in the gut.
Stress-induced changes to the microbiome may in turn affect the brain and behavior. A few studies suggest that defensive molecules the gut produced during infection, called inflammatory cytokines, disrupt brain neurochemistry and make people more vulnerable to anxiety and depression. Bercik believes that process may help explain why more than half of people with chronic GI disorders such as Crohn’s disease, ulcerative colitis and irritable bowel syndrome (IBS) are also plagued by anxiety and depression.
In one study, published in the British Journal of Nutrition in 2011, researchers found that a 30-day course of probiotic bacteria (a mix of Lactobacillus helveticus and Bifidobacteria longum) led to decreased anxiety and depression in healthy human volunteers.
A study published in 2014 found that many people with non-celiac gluten-sensitivity report feeling better when they avoided the consumption of gluten, and that “short-term exposure to gluten specifically induced current feelings of depression.”
So what does all of this mean for people who have not been diagnosed with celiac disease or non-celiac gluten sensitivity?
While a link between gluten and depression has not been proven, the evidence – both scientific and anecdotal – is compelling.
Dr. William Davis, cardiologist and author of the best-selling book Wheat Belly, has noticed that when his pre-diabetic and diabetic patients follow a wheat and grain-free diet, they show improvements in (or total relief from) inflammation-related diseases and disorders – including more stable moods and emotions.
In a May 2014 study in Alimentary Pharmacology & Therapeutics, people with irritable bowel syndrome reported better moods when they weren’t eating gluten, despite their continuing gastrointestinal symptoms.
David Johnson, MD, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, says that there’s some evidence that gluten may cause depression in patients with non-celiac gluten sensitivity. Some research suggests that the bacteria in the gut can affect both mood and behavior, according to Dr. Johnson. ”Eating gluten may change the bacteria in the gut,” and that, in turn, could potentially change behavior, he says.
How do you figure out if gluten is causing or contributing to your mental health challenges? If you believe you may have celiac disease, it is important to consult with your healthcare provider because of the seriousness of the disorder. If you don’t think you have celiac disease, but believe you might benefit from avoiding gluten, it couldn’t hurt to try. Humans don’t NEED to consume gluten, and many people report feeling better after removing it from their diet.