Gluten and gluten-free diets have certainly grown in awareness and popularity but whether or not to follow this dietary restriction is often poorly recognized. Just as there are claims that 'sugar is the root of all evil', some argue that gluten-containing foods are responsible for ill health effects across the board. So what exactly is gluten and do you need to avoid it?
Gluten is a protein product of a chemical reaction that occurs when combining the wheat proteins glutenin and gliadin + water + mechanical work. [When these wheat proteins glutenin and gliadin are combined with water and mechanical work (kneading) this will usually form a dough.] In this respect, foods that contain wheat proteins (and further dough formation) would be considered gluten-containing foods, whereas foods without these wheat proteins would be considered gluten-free. If an individual were required to follow a gluten-free diet, this would mean avoiding wheat, barley, rye, regular oats (due to potential cross-contamination), and many products that contain wheat like dough-based foods, but also foods where wheat can be used as a stabilizer like soy sauce, soups, imitation crab meat, beer, licorice, malt products, many condiments, and more. (Jones, 2017) **There is a reason why other grains (other than wheat, rye and barley) would be avoided on a gluten-free diet as there is a risk for cross-contamination in the cultivating and processing of grains. This is why you may seem some packages of non-wheat foods, like oats, being labeled gluten-free as this is assurance that there is no potential cross-contamination. But this is also why many individuals who are required to follow a gluten-free diet can run into issues from low grain intake/not choosing adequate alternatives.
Gluten can certainly have a negative impact on the health of those who are unable to digest the wheat proteins (gliadin and glutenin) as can be seen in individual's with Celiac disease. In these cases, following a gluten-free diet is not only warranted, it is a lifelong prescription in order to maintain adequate health and functioning. **It should be noted that for these individuals who NEED to follow a gluten-free diet for life, there are certainly many benefits to the growing awareness and recognition of gluten with increases in gluten-free food labeling and availability, and more prevalent identification of gluten-free foods in grocery stores and on restaurant menus. For these individuals, the gluten-free craze is certainly a benefit.
How do you know if you are intolerant of, or sensitive to, gluten?
Now gluten intolerance and gluten sensitivities can occur in a spectrum of severity and presentations where for example Celiac disease is actually identified as an inherited autoimmune disorder that affects approximately 1% of the population, whereas gluten sensitivity is poorly defined but is associated with a heightened immune response to gluten, and a wheat allergy is an immediate IgE immune response to wheat (an allergic response like respiratory, skin, or gastrointestinal symptoms within immediate ingestion of wheat). (Kohlstadt, 2012) [It should be noted that CD and wheat allergy can be diagnosed with serologic testing, but gluten sensitivity cannot.]
As noted, Celiac disease is characterized as an immune-mediated inflammation (and subsequent damage) of the small intestine in response to gluten (from wheat, rye and barley) ingestion and is noted to be a genetically-determined autoimmune trait with an environmental trigger (gluten). (Kohlstadt, 2012) Celiac disease is diagnostically identified by the presence of IgA antibodies (specifically anti-tissue transglutaminase, or TTG antibodies). (Kohlstadt, 2012)
Some of the presenting symptoms of Celiac disease may include (but not limited to):
general and chronic weakness
weight loss (inability to maintain weight)
gastrointestinal issues like diarrhea/ constipation
abdominal pain and distention
cramps
bone pain/osteoporosis
myopathy
skin rashes
iron deficiency/ anemia
neurological complications like depression, anxiety, etc
peripheral neuropathy
and more. (Kohlstadt, 2012)
[Some symptoms are due to GI mucosal damage from the inflammatory immune response like GI complications, whereas other symptoms are due to downstream effects of nutrient malabsorption and deficiency.] Interestingly, there has been an increase in the prevalence of Celiac disease since the 1970's, NOT due to increased sensitivity of testing. (Kohlstadt, 2012) It can be argued instead that these increases may be due to adults losing their immunologic tolerance to gluten. (Kohlstadt, 2012) However it could also be argued that this increased prevalence in the last 40+ years could be due to more accurate diagnostic criteria whereas these symptoms may have been previously misdiagnosed as irritable bowel syndrome or other similar GI/malabsorption conditions. **A major issue with obtaining accurate serologic tests (for total IgA and TTG antibodies) to determine a diagnosis of Celiac disease is the fact that the individual must be eating a gluten-containing diet during the time of the test to avoid false negatives. (Jones, 2017) This can become a diagnostic issue if the individual had been following a gluten-free diet for months before being tested as the serologic markers would not be an accurate reflection of the body's response to gluten (but rather it's response, or lack thereof, to the absence of gluten, which is not enough to deem a diagnosis for Celiac disease).
There can be a sensitivity to gluten without the presence of the autoimmune condition of Celiac disease (also known as non-Celiac gluten sensitivity). In this case, there are symptoms present that may be associated with the ingestion of gluten, but without the presence of antibodies in serologic testing, and possibly without the intestinal damage often associated with the autoimmune condition. Without specific diagnostic criteria, many individuals may fall into this category, with varying degrees of sensitivity. In this case, due to an inability to accurately characterize and diagnose a 'sensitivity' to gluten and gluten-containing foods, this umbrella term therefore encompasses a wide variety of manifestations. **To this point, there could be a lot of individuals with self-reported gluten sensitivity, but without an accurate method to quantify sensitivity, there is not yet a real diagnosis for it, nor a way to accurately study its progression and/or treatment.
What happens when someone goes on a gluten-free diet?
It depends on:
what the individual was eating before going GF
whether or not they actually are sensitive to, or intolerant of, gluten specifically
how their 'gluten-free diet' actually looks
For someone who is genuinely sensitive to, or intolerant of, gluten, then the elimination of gluten from the diet would boast a significant improvement in mal-digestive symptoms (abdominal pain, cramps, bloating, diarrhea/constipation, etc) and if the diet is nutritionally adequate, then further symptoms may improve as a decrease in gut inflammation has allowed for appropriate nutrient absorption and could theoretically correct for nutrient deficiencies. An example of nutritionally adequate dietary carbohydrate intake if avoiding gluten-containing carbohydrate foods would equate to plenty of vegetables, fruits, legumes, and gluten-free grains like buckwheat, quinoa, millet, sorghum, amaranth, rice and teff. (Jones, 2017)
In an individual who may NOT be sensitive or intolerant to gluten, but has instead changed their diet to include more whole foods like vegetables, fruits, legumes, non-gluten whole grains, lean protein sources and less refined flours and sugars, they too would likely see positive health changes but this may not be due to the lack of gluten in the diet, but rather the emphasis placed on nutritionally dense whole foods (particularly high in fiber!). **This can often times lead to a false association between previous symptoms and a gluten sensitivity specifically due to the fact that changing the diet (in this case including more nutrient-dense whole foods) is surely to benefit an individual (and likely improve symptoms) regardless of whether gluten was the issue or not, but based primarily on the increase in nutrient density (and fiber content) of their food choices.
Then of course there is the individual, who may or may not have an actual sensitivity or intolerance to gluten, but instead chooses gluten-free versions of their favorite processed foods without actually emphasizing nutrient dense (and fiber-rich) foods (choosing gluten-free brownies and cookies instead of the regular). In this case, the removal of gluten MAY help with some GI inflammation IF there is an actual sensitivity present, but where arguably, many of their symptoms are likely to still remain as there is still a lack of nutritional adequacy from the diet. This is one of the largest risks for following a gluten-free diet if not formerly diagnosed to do so as there is an increased risk for nutrition deficiency with gluten-free processed grain products (breads, cereals, crackers, etc) as they are lower in fiber, iron, zinc, potassium, the B vitamins and other trace minerals. (Jones, 2017) Furthermore, there are study findings to suggest that individuals following a gluten-free diet ate less than half of the recommended daily grain intake, and what they did eat was largely from rice and corn, which are lower in fiber, protein and micronutrient content compared to the other whole grains. (Jones, 2017) Add to this a lack of nutritional adequacy from food choices (simply choosing GF alternatives to already low nutrient dense foods i.e. GF 'junk foods'), and this diet could end up further impairing an individual's health.
Much of the buzz about gluten-free diets over recent years is based around unsupported claims that a gluten-free diet is healthier, can aid in weight loss, and can aid in treatment of a variety of health concerns (anything from IBS to lactose intolerance, irritability, autism, and more). (Jones, 2017) Unfortunately, MOST of these claims lack scientific evidence. When it comes to weight loss claims, for those who have Celiac disease, a gluten-free diet can actually lead to weight GAIN (which is often a benefit for CD individuals as this means that they are able to absorb and utilize nutrients from food compared to issues with malabsorption prior to the GF diet). (Jones, 2017) However, for non-Celiac individuals, this may pose an issue where many gluten-free alternatives are higher in fat and calories while also being lower in fiber than their gluten-containing counterparts. (Jones, 2017)
There are some claims from the gluten-free diet supporters stating that gluten is toxic, yet there is NO scientific evidence to support this claim. (Reilly, 2016) Even in those diagnosed with Celiac disease, gluten itself is NOT a potential toxin, but rather where gliadin (the naturally-found wheat protein) fragments are recognized by the innate and adaptive immune system (like memory cells) that trigger an immune response (cytokine release and mucosal damage). (Reilly, 2016) *This means that in these individuals (genetically susceptible for CD), the exposure to this food protein (an environmental trigger) stimulates the autoimmune response. But take note: this is NOT the food protein that is causing the reaction, but miscues in the body due to a genetic predisposition (an inherited alteration).
There are further theories to suggest that it is increased intestinal permeability (increased ability for proteins to pass through the intestinal cell layer) that is largely responsible for reactions to gluten (namely gliadin fragments) and not necessarily gluten itself. (Reilly, 2016) In this sense, there could be a number of foods with protein fragments that could initiate an immune response by passing through the more permeable intestinal wall. This is often termed 'leaky gut syndrome' where the intestinal cell layer (which is only one cell layer thick) becomes inflammed causing the cells to pull away from one another and form openings with which protein fragments from digestion in the small intestine can pass through these openings into the abdominal cavity and elicit an immune reaction in response to these 'foreign invaders'. It should be noted that these food protein fragments are NOT inherently good or bad but rather are located in an area where they are not typically found (and thus not recognized as 'self' but as a foreign invader) which leads to an inflammatory immune response and further down-stream effects if left unaddressed. **This is proposed as a reason why gluten sensitivities may fall on a spectrum of intensity as there is not an innate or acquired allergy (IgA or IgE) but rather a sensitivity due to functional mal-absorption, and not due to a 'toxin or antigen' in the food protein itself. If this is the case, then addressing the underlying cause (the leaky gut) with treatment to improve gut permeability can improve conditions enough to where avoiding gluten would not need to be a life-long adherence.
References:
Jones A. The Gluten-Free Diet: Fad or Necessity? Diabetes Spectrum. 2017; 30(2):118-123. http://spectrum.diabetesjournals.org.proxy.lib.fsu.edu/content/30/2/118
Kohlstadt I. Advancing Medicine with Food and Nutrients. 2nd edition. CRC Press. Boca Raton, FL. 2012.
Reilly N. The Gluten-Free Diet: Recognizing Fact, Fiction, and Fad. The Journal of Pediatrics. 2016; 175:206-210. http://www.sciencedirect.com.proxy.lib.fsu.edu/science/article/pii/S0022347616300622?via%3Dihub