An Evidence-Based Report on Gluten Intolerance and Celiac Disease
Aaron Jahn
Personal Trainer | Kettlebell Specialist | Minimal Equipment Programs | Fat Loss & Performance Training
Humans have existed in some form or another for around 2.5 million years, but only in the last 10,000 years have we been exposed to wheat. Nutritional needs increased enormously during the 20th century due to the food shortage in the first half of the century (the result of two World Wars) and the rapid growth in world population in the second half of the century. Consequently, agronomists and geneticists set out to develop new varieties of wheat that were stronger and richer in gluten content.
In 1941, the Nutrition Society identified the need to increase wheat production and grow the worldwide wheat production by 500% by the end of the 20th century. Although there is currently no data to confirm the hypothesis, it is likely that these new varieties of wheat which are enriched in gluten content have contributed considerably to the dramatic increase in gluten-related diseases. This growth in wheat production may also have affected the prevalence of celiac disease which was reported as being 1:8000 individuals in the UK in 1950 and has now increased to approximately 1% of the global population.
The recent expansion in the market for gluten-free food products far exceeds the expected consumption by celiac disease population, raising questions relating to gluten reactions other than celiac disease and wheat allergy. Indeed, many individuals reportedly suffer from problems caused by wheat and/or gluten consumption, but do not have celiac disease or wheat allergies and choose to eliminate wheat and gluten from their diets. The motivation for doing so is normally due to experiencing unfavourable symptoms following the ingestion of wheat-containing foods and the benefits obtained from adopting a gluten-free diet.
It appears that the general population has adopted this line of thought more readily than the scientific/medical community, with many individuals relying on self-diagnosis i.e. the hypersensitivity to wheat and gluten, and subsequent therapy such as the gluten-free diet. In fact, the non-medical specialist press has indicated that 17 million Americans are gluten sensitive, with many of these patients reporting a long clinical history including gastrointestinal symptoms such as abdominal pain, irregular bowel habits, and diarrhoea or constipation. These individuals often attempt to reach a diagnosis of celiac disease by their physicians but are typically considered to be suffering from irritable bowel syndrome.
Wheat and Gluten
Gluten is the word used to describe the protein mixture of glutelins and gliadins (prolamins) which is present in the endosperm of wheat and cereals such as rye, spelt and barley, and are not completely digestible by intestinal enzymes. This partial digestion results in a mix of peptides that can trigger a number of responses such as increased intestinal permeability and an immune response which is similar to those provoked by exposure to gastrointestinal pathogens.
Currently, gluten is one of the primary dietary components for the majority of the world's population, particularly in Europe and the United States. In fact, the average consumption is 10-20 g per day in the Mediterranean area and even greater in other populations.
New types of wheat have emerged due to agricultural mechanisation and the increased industrial use of pesticides and fertilisers, which might play an important role in the adverse immunologic reactions to gluten. Furthermore, the bread leavening process has shortened significantly, resulting in a higher concentration of toxic gluten peptides in many baked goods.
Clinical Presentation
Celiac Disease - The clinical presentation of celiac disease is varied and is dependent on the age of the individual. The classic symptoms of failure to thrive, abdominal pain, diarrhoea and malnutrition within the first few years of life depict the apex of what is often referred to as the 'celiac disease iceberg'.
Diarrhoea is the symptom most commonly present in untreated celiac disease and effects 45-85% of patients. It is caused by the maldigestion and malabsorption of nutrients, and leads to watery stools with foul odour. In young children, prolonged symptoms of diarrhoea can invoke severe dehydration and electrolyte depletion.
Children and adolescents also typically present with short stature and an inherent delay of puberty, while adults may present with?anaemia or osteoporosis.
Nonceliac Gluten Sensitivity - The clinical symptoms of nonceliac gluten sensitivity occur following the consumption of gluten-containing grains, and improve or disappear completely with the elimination of these grains from the diet. Symptoms then reappear on cessation of the gluten challenge - normally within a number of hours or days.
The clinical gastrointestinal presentation of nonceliac gluten sensitivity is characterised by symptoms such as abdominal pain, bowel irregularity (constipation, diarrhoea, or both) and bloating, while extraintestinal symptoms include 'brain fog' (impaired cognitive function, poor memory, decreased levels of alertness), headaches, fatigue, depression, numbness of limbs, dermatitis, and joint and muscle pain.
Assessment and Diagnosis
Celiac Disease - There has been a growth in the availability and application of precise non-invasive instruments for the diagnosis of celiac disease in the past 20 years. The measurement of serum IgA antibodies?to tissue transglutaminase is a screening procedure with high sensitivity and specificity, and is the first screening test that should be arranged for individuals in whom celiac disease is suspected.?The IgA antiendomysial antibody measurement is 98% specific for active celiac disease, but should only be implemented as a confirmatory test due to its cost and subjective interpretation.
Villous blunting on the small-intestinal biopsy can definitively determine the presence of celiac disease and is advocated by?NASPGHAN and the ACG.
Nonceliac Gluten Sensitivity - Currently, no specific biomarkers for nonceliac gluten sensitivity have been identified. Clinicians typically consider a diagnosis of nonceliac gluten sensitivity in patients who present with gastrointestinal or extraintestinal symptoms that improve with the elimination of gluten from the diet. However, as these symptoms can also be present in patients with celiac disease and, to a lesser extent, with wheat allergy, they must be excluded with?with serologic and histologic evidence to home in on the suspicion of nonceliac gluten sensitivity.
Until biomarkers are established and approved, the diagnosis of nonceliac gluten sensitivity can only practicably be confirmed in a research setting via a double-blind crossover gluten challenge.
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Treatment
A strict gluten-free diet is currently the only feasible treatment for gluten-related disorders. However, the time frame is different depending on the specific disorder.
The research suggests that nonceliac gluten sensitivity is a transient condition. Patients may therefore benefit from adopting a gluten-free diet for a specific period of time e.g. 12 to 24 months, before testing gluten tolerance again. Then, based on the severity of subsequent symptoms, some gluten-sensitive patients may benefit from adopting a gluten-free diet permanently.
The only viable option for those with celiac disease is a lifelong adherence to a gluten-free diet. The implementation of this diet can be problematic as minuscule amounts of gluten may be present in supposed gluten-free foods. Trace amounts such as these can be just as damaging as a complete lack of adherence to a gluten-free diet.
Experts on gluten-related disorders recommend that patients diagnosed with either condition be monitored by a gastroenterologist and a qualified dietitian to guide the patient and their family through the intricacies of the gluten-free diet.
Practical Questions
Should the family members of celiac disease patients be tested?
First degree family members of celiac disease patients are 15- to 25 times more likely to develop celiac disease based on their genetics, compared with individuals? who do not have a first degree family member with a positive diagnosis of celiac disease. Therefore, ESPGHAN, NASPGHAN, and ACG recommend screening first-degree family members whether signs and symptoms of celiac disease are present or not.?Other guidelines suggested by these organisations include the induction of screening by age 3 and, if results are negative, repeating the screening procedure throughout the patient's lifetime.
Is a gluten-free diet beneficial for those who do not appear to have a gluten-related disorder?
Research does not support the notion that a gluten-free diet is part of a healthier lifestyle or can aid in the treatment of obesity. The incomplete digestibility of gluten goes some way to explain why some individuals report improvements in general well-being after adopting a gluten-free diet.
Additionally, gluten-containing cereals, particularly wheat, are a?primary source of FODMAPs (fermentable oligosaccharides, disaccharides,?and monosaccharides and polyols) which are a class of poorly absorbed short-chain carbohydrates and polyols. The reduction or complete elimination of FODMAPs associated with the gluten-free diet may also explain why some individuals presenting with irritable bowel symptoms report improvements in their condition after adopting a gluten-free diet.
The self-diagnosis of nonceliac gluten sensitivity is not advised as a misdiagnosis may lead to incorrect treatment.
Summary
Both nonceliac gluten sensitivity and celiac disease are common conditions. Although they are treated by adopting a gluten-free diet, it is important to differentiate between celiac disease and gluten sensitivity long-term therapeutic intervention. Individuals with a positive diagnosis of celiac disease should be followed up for adherence to the gluten-free diet, any nutritional deficiencies, and the development of comorbidities.
Foods that should be avoided on a gluten-free diet (unless they are specifically labelled as 'gluten-free') include;
The elimination of processed foods and the inclusion of whole foods is a sensible approach to take when adopting a gluten-free diet. Foods that can be consumed on a gluten-free diet include;
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