FOOD ALLERGY, GLUTEN INTOLERANCE AND CELIAC DISEASE

 

Some form of digestive disorder affects millions of people around the world. For some people, digestive disorders are a source of irritation and discomfort that may cause them to significantly limit their lifestyles and frequently miss work. For others, the disorders may be rather serious. Despite the fact that food and diet are central issues that concern many patients attending gastroenterology clinic, the current understanding and explanation about the association between the intake of certain foods/food groups and the gastrointestinal (GI) symptom pattern, psychological symptoms, and quality of life may not be simple and straightforward.

The gastrointestinal (GI) tract is a long muscular tube that functions as the food processor for the human body. The digestive system includes different organs working in close harmony to digest the food and absorb the nutrients. However, GI tract is not a passive system. Rather, it has the capability to sense and react to materials passed through it. For a healthy digestive system, every person requires somehow different food selections that match their GI tract capacity.

The GI tract breaks down foods by first using mechanical means (e.g., chewing) and then via the application of complex chemical processes (from saliva to colon microbes). Since the GI tract is the point of entry for the human body, everything eaten has an impact on the body. The food eaten and passed through the GI tract contains nutrients as well as non-nutritional additives and contaminants. Additives and contaminants can include, but are not limited to, food additives, pesticides, bacteria or chemicals that induce a reaction from the GI tract.

GI tract is very important sensory organ. By rejecting foods through objectionable taste, vomiting, diarrhea, or any combination of these symptoms, the sensing capacity of the GI tract can protect the body. The immune sensors in the GI tract trigger responses such as nausea, vomiting, pain, swelling and diarrhea. Vomiting and diarrhea are abrupt defensive responses when it senses foods or contaminant with a allergic or toxic component. This kind of food intolerance is responsible for many digestive problems.

Food allergy is sometimes the primary cause of GI tract problems. The dysfunction, discomfort, and disease associated with the GI tract can be the result of local immune responses to food selections or combinations of foods. Food selections are a result of personal tastes, social fads, ethnic culture, religion, and local or seasonal availability. Food selections made in modern society are based on a developed taste for a rich diet centered on meats and dairy products, high concentrations of proteins, simple carbohydrates, processed food and fat-soluble additives.

The effect of the shift in our diets during the past 100 years has resulted in increasing amount of people suffering from reflux, bloating, non-ulcer dyspepsia, diarrhea, constipation, diverticulosis, gallstones, fatty liver, and even a cancer.

Detailed medical history, evaluation of dietary habits and food selection and physical examination are the first modalities used in approach for evaluation of GI conditions. There are few basic symptoms indicating a GI tract problem.

Nausea and Vomiting

Nausea and vomiting can vary from an unsettled feeling in the stomach to the violent action of immediate vomiting. Nausea and vomiting are linked to may GI conditions and also to some non-GI disorders.

Bloating
Bloating can result from excessive gas in the digestive system due to fermentation and swallowing air while eating or failure of the digestive tract to break down nutrients into small absorbable molecules (e.g lactose intolerance or celiac diseases).

Constipation
Constipation is the decreased frequency or slowing of peristalsis, resulting in harder and infrequent stools. When the GI tract is slowed down, feces can accumulate in the colon with attending pain and bloating. It is often result of inadequate water and fiber intake and increased intake of processed and fatty food.

Diarrhea
Diarrhea is the increased frequency of bowel movements, which are also loose or watery. Diarrhea could be associated with food allergy or celiac disease, but is also present in other inflammatory bowel conditions or irritable bowel.

Abdominal Pain

Abdominal pain appears in different patterns and with varying intensities. It is a common symptoms of various GI problems.

What is (a) gluten intolerance, and (b) coeliac disease? What are the symptoms that you see? What is the treatment?

Celiac disease is an immune-based reaction to dietary gluten (storage protein for wheat, barley, rye) which affects the small intestine in those with a genetic predisposition and resolves with exclusion of gluten from the diet. There has been a substantial increase in the prevalence of celiac disease over the last 50 years and an increase in the rate of diagnosis in the last 10 years.

Celiac disease is one of the most common causes of chronic malabsorption. This results from injury to the small intestine with loss of absorptive surface area, reduction of digestive enzymes, and subsequently impaired absorption of micronutrients such as fat-soluble vitamins (A,D,E,K), iron, and vitamin B12, folic acid, zinc, etc. In addition, the inflammation worsens symptoms of malabsorption by causing secretion of fluid into the intestine that can result in diarrhea. The failure of absorption of adequate calories and nutrients leads to weight loss, and the malabsorption results in abdominal pain and bloating.

Therefore, celiac disease can present with many symptoms, including typical GI symptoms (e.g., diarrhea, oily stools, weight loss, bloating, flatulence, abdominal pain) and also non-gastrointestinal abnormalities (e.g., abnormal liver function tests, iron deficiency anemia, bone disease, skin disorders, itchy skin rash and many other manifestations). Indeed, many individuals with celiac disease may have no symptoms at all.

Celiac disease is usually detected by blood test – testing of specific gene carrying the predisposition and celiac-specific antibodies. The diagnosis is confirmed by small intestine (duodenal) mucosal biopsies taken during gastroscopy. Both blood test and biopsy should be performed when patient is taking gluten containing diet. When someone is on gluten-free diet, antibodies blood test and biopsies could be only done after daily exposure to gluten for at least 3 weeks.

The treatment for celiac disease is primarily a gluten free diet, which requires significant patient education, motivation, and follow-up.

Non-celiac gluten sensitivity or simply gluten sensitivity is defined as “a clinical entity induced by the ingestion of gluten leading to intestinal and/or extraintestinal symptoms that improve once the gluten-containing foodstuff is removed from the diet, and celiac disease and wheat allergy have been excluded”.

The pathogenesis of non-celiac gluten sensitivity is not yet well understood. Non-celiac gluten sensitivity is a controversial clinical condition and some authors still question it. Non-celiac gluten sensitivity is the most common syndrome of gluten-related disorders with prevalence rates between 0.5–13% in the general population.

However, at this time, it appears that non-celiac gluten sensitivity does not have a strong hereditary basis, is not associated with malabsorption or nutritional deficiencies, and is not associated with any increased risk for auto-immune disorders or intestinal malignancy. There is no specific blood test for diagnosing this condition, so diagnosis is made by exclusion of other gluten-related disorders, namely by excluding celiac disease and wheat allergy.

 

Why food allergies are becoming more and more common?

Celiac disease is a chronic inflammatory disorder of the small intestine, produced by the ingestion of dietary gluten products in susceptible people. It is a multifactorial disease, including genetic and environmental factors. Environmental trigger is represented by gluten while the genetic predisposition has been identified on certain parts of our genetic material (HLA DQ2 and DQ8). Celiac disease is not a rare disorder like previously thought, with a global prevalence around 1%. The reason of its under recognition is mainly referable to the fact that about half of affected people do not have the classic GI symptoms, but they present nonspecific manifestations of nutritional deficiency, autoimmune conditions, irritable bowel or have no symptoms at all.

There has been a substantial increase in the prevalence of celiac disease over the last 50 years and an increase in the rate of diagnosis in the last 10 years. The reasons for increasing frequency of celiac disease are unclear but could be related to recent dietary changes, gluten-rich dietary patterns,  processed foods, microbiota etc.

Celiac disease was originally thought to almost exclusively affect white Europeans. The frequency of celiac disease risk HLA genotypes is about 30%, whereas only 1%-3% develops celiac disease. The prevalence varied geographically, higher in Northern Europe and the African Saharawi region than in South-East Asia. However, recent epidemiological studies conducted in areas supposedly free of celiac disease, including Africa, the Middle East, India, and South America, showed that the disease was previously underdiagnosed.

The world distribution of celiac disease seems to have followed the mankind wheat consumption and the migratory flows. Man originally fed on meat, fruit and vegetables, with no exposure to gluten-containing cereals. It was only about 10 000 years ago in a small region called the “Fertile Crescent” of the Middle-East (including Anatolia (Southern Turkey), Lebanon, Syria, Palestine and Iraq) where wild wheat and barley grains successfully cultivated due to favourable environmental conditions. In the Fertile Crescent some tribes changed from nomadic to stable settlement style of living because land cultivation permitted food storage, and later migrated westwards to obtain new lands for cultivation. These persons spread through the Mediterranean area (Northern Africa, Southern Europe) and Central Europe. The expansion continued from 9000 to 4000 BC by which time the cultivation of wheat and barley had spread all over the Old Continent, also reaching Northern Europe (Ireland, Denmark and the Scandinavian countries). This expansion in farming was due to the diffusion of agricultural practices and replacement of local inhabitants.

 

“Gluten sensitivity” has become commonplace among the public. Wheat allergy and celiac disease are well-defined entities, but are becoming only a fraction of individuals following a gluten-free diet.

Wheat allergy has a prevalence of <0.5%. Wheat is the most common allergen implicated in food-dependent, exercise-induced anaphylaxis. Celiac disease is hypersensitivity to gluten in genetically predisposed individuals. In addition to suggestive symptoms, serologic testing has high diagnostic reliability and biopsy is a confirmatory procedure.

However, many people follow gluten free diet as a consequence of media and industry, without appropriate medical evaluation and testing. There is a huge misconception about gluten free diet. It is essential for people diagnosed with celiac disease. However people without this condition often mistakenly adopt “gluten free diet” and consuming gluten free food in belief it is “healthier.

The gluten-free food is sometimes promoted as a way to lose weight, or as a “healthier” food. There is no evidence that gluten free food is beneficial for people who do not have celiac disease. Not only that. Gluten free food is not the same as staying gluten free. Patients with celiac disease are aware about this difference and they avoid commercially prepared gluten free food substitutes and focus their diet on naturally occurring food choices which do not contain gluten.

However, commercially prepared gluten-free food contains dietary substitutes and additives which are usually not healthy. Misconception is that eating gluten-free food leads a healthy lifestyle. The average commercially made gluten-free food is highly processed and containing lots of additives. The biggest problem with the “Gluten-Free Diet” in general population without proper guidance is the reliance on these commercially prepared processed foods that are low in nutrients and high on additives.

The standard commercially prepared Gluten-Free Food typically contain several specific food components:

  • Cereal grains (corn, rice, soy)
  • Seed oils (Canola oil, Rapeseed oil, safflower oil, and sunflower oil)
  • Sugar (high-fructose corn syrup)
  • Artificial sweeteners
  • Food additives (xanthan gum, guar gum, soy substitutes)

Even though gluten was removed – the Gluten-Free commercially prepared food relies heavily on the other agents, additives and substitutes. In fact, many types of commercially prepared gluten-free foods are loaded with higher concentrations of food additives than their original counterparts.

The recommendation would be, if someone suspect any food intolerance or allergy, get proper medical evaluation and testing to avoid further health problems.