Updated: Dec 19, 2018
Gluten-free diet has become more popular – almost every supermarket has a gluten-free section. Many restaurants have put gluten-free options on their menu. It seems that most people who do not have coeliac disease are also on a gluten-free diet. Moreover, a recent research suggested a link between eating gluten during pregnancy and type 1 diabetes risk in children. Is gluten-free diet a fad? Should we avoid gluten? Let's find out...
People who do not eat wheat or gluten mainly because they react to it. There are two subgroups of gluten reactivity:
(i) Coeliac disease which is about 1-2% of the population. Coeliac disease is an autoimmune condition that causes damage to the lining of the small intestine where the nutrients are absorbed. It involves genetic component called HLA-DQ2 and DQ8, which predispose an individual to the disease. When gliadin peptide (protein found in wheat, rye and barley) is not properly digested, this then causes inflammation in the gut, initiating an enzyme called transglutaminase to deamidate the gliadin peptide. The immune system reacts by producing antibodies against gliadin peptides and transglutaminase. If the result from tissue biopsy shows abnormality, then this confirms coeliac disease. Notably, there are many undiagnosed coeliac disease cases called silent coeliac disease or atypical coeliac disease. This is because the only way to detect coeliac disease is to do a blood test followed by tissue biopsy. People with coeliac disease must avoid gluten for life otherwise it would cause damage to the surface of the small intestine resulting in malnutrition which could lead to other long-term complications including osteoporosis, anemia (caused by iron, vitamin B12 and folate deficiency) as well as may affect pregnancy.
(ii) Non-coeliac gluten sensitivity (NCGS) in which case the immune system produces IgG or IgA antibodies against gliadin and/or other wheat proteins but no antibody against transglutaminase, and tissue biopsy is normal. Unfortunately, the classic blood test for coeliac disease is unable to detect NCGS because it only measures antibodies against just one component of wheat whereas an individual could react to other wheat peptides. This undetected/unknown NCGS could eventually develop to an autoimmune disease because the body continues to react against gluten for years. In addition, it is well-established that gluten increases gut permeability (i.e. leaky gut), which is the main trigger of autoimmune disease. Leaky gut allows undigested food protein like gliadin peptide get into the bloodstream and cause the immune response against it. The antibodies produced against gluten will also attack the body’s own tissue causing autoimmunity due to similarity between gluten (as well as other food antigens such as casein in milk) and human tissue (e.g. thyroid, joint, neurons). Moreover, environmental factors such as infections or toxic chemicals are also the main triggers of autoimmunity. Toxins can bind to human tissue causing modification and autoantibodies against our own tissue. That’s why people with an autoimmune disease such as rheumatoid arthritis who avoid gluten and/or dairy (or any other food sensitivities) feel significantly better.
Unfortunately, the classic blood test for coeliac disease only measures antibodies against just one component of wheat whereas an individual could react to other wheat peptides.
Should you avoid gluten?
The answer is it depends on whether you are sensitive to gluten or not. Unlike coeliac disease which usually results in gastrointestinal (GI) symptoms such as diarrhea, stomach pain and bloating, NCGS can cause a wide range of symptoms, both GI and non GI symptoms such as brain fog, fatigue, headache, joint and muscle pain. It can be difficult to relate these symptoms to gluten sensitivity unless you eliminate gluten and feel better or do a comprehensive blood test for gluten sensitivity. So if you already have an autoimmune disease, avoiding gluten (and other inflammatory foods) is likely to help improve your symptoms. Or if you have a family history of autoimmunity, avoiding gluten can remove the trigger.
Are you on a gluten-free diet? Has avoiding gluten helped with your symptoms? Please give your comment below.