Irritable Bowel Syndrome: A Local Allergy Response to Histamines?
Irritable bowel syndrome (IBS) has been at very high levels around the globe for a number of years. It is estimated that some 20% of the world’s population suffers from this condition. So, what is IBS and what causes this painful and debilitating disorder?
What Is Irritable Bowel Syndrome?
Irritable bowel syndrome is categorised as a chronic functional gastrointestinal disorder, which presents with abdominal pain. It can be associated with defecation issues like diarrhoea and changing stool frequency and form. IBS impacts upon the sufferer’s quality of life, especially in its more severe manifestations. Despite this it is not considered to effect mortality. IBS does not negatively impact bowel tissue or increase the sufferer’s risk of colorectal cancer (Basnayake C, 2018).
Those who have IBS can experience cramping, gut ache, bloating, gas, diarrhoea or constipation. For many sufferers, there are no quick fixes for this ill-favoured condition and long-term management is their only way forward. Debilitating disorders around going to the toilet can not only be embarrassing but terribly inconveniencing. Therefore, IBS adversely impacts individual’s ability to carry out normal tasks associated with living. Work and the kind of jobs a person with severe IBS can do are affected by this condition. Playing sport becomes very difficult and doing anything far from a toilet becomes challenging. Relationships can be negatively impacted by IBS and a sympathetic partner is required in most instances. Romance and passion are not comfortable bedfellows with IBS.
What Causes Irritable Bowel Syndrome?
Until quite recently, IBS had been something of a mystery. One of a number of chronic health issues plaguing the modern world, especially populations in wealthy western countries. Medical science observed that IBS was affecting muscle contraction in the intestinal wall. Layers of muscle line the walls of the intestines and these contract as food is moved through the digestive tract. Heavier contractions can result in bloating, gas, and diarrhoea. While weaker contractions promote slower digestive action, hard stools, and constipation. The diet is obviously a contributing factor in IBS and manipulation of dietary input has been at the forefront of some therapeutic approaches to alleviating this gastrointestinal disorder. However, it must be remembered that medical science has long been more inclined to prescribe a pharmaceutical or surgical solution to most illnesses and conditions. Only more recently has the study of nutrition begun to be accorded greater recognition for its efficacy in the treatment of chronic illnesses like IBS. Food as medicine has long been a foreign and largely outdated concept for those running the medical science departments in the citadels of learning around the globe. The nervous system has been linked to the digestive system in recent times via studies into how these two can impact upon each other. Stress and mental health issues have been observed to be accompanied by conditions like IBS. The relatively new awareness of the gut microbiome has shone a bright light on the connection between brain and bowel. Changes in gut bacteria, fungi, and viruses are now understood to play a major role in the holistic health of human beings. However, the most conclusive cause lately discovered by medical science is the role of histamines in the biological mechanism triggering IBS symptoms such as abdominal pain.
The Role of Histamines in Triggering IBS
Exciting new research at KU Leuven in Belgium has revealed the role of histamines released from mast cells as an immunological response to certain foods. These histamines produce pain and discomfort in the sufferer as part of the IBS suite. A healthy intestine will not have an immune response to these foods. The findings support the known data around IBS, in that people with the condition often report its genesis occurring after a gastrointestinal infection like food poisoning. The hypothesis for researchers was that the gut becomes sensitised to the food/protein present when the infection occurred. Thus, they set out to test via animal studies whether the food associated with gastrointestinal infection can then generate the immune response post the infection period and going forward. The results affirmed their understanding, with the food containing the protein provoking mast cell activation and the production of histamine. The biological mechanism within our gut links the particular food with the previous infection and generates an immunological response upon this basis. Interestingly, this response is localised to the intestinal area of the original bacterial infection and does not produce a more general allergic reaction. The researchers then tested the same hypothesis on humans with IBS, by injecting food antigens associated with IBS into the intestinal wall. Gluten, wheat, soy and cow milk were all tested and produced localised immune reactions similar to those observed in the test mice. Professor Guy Boeckxstaens, who led the studies, said, “This is further proof that the mechanism we have unravelled has clinical relevance … knowing the mechanism that leads to mast cell activation is crucial, and will lead to novel therapies for these patients. Mast cells release many more compounds and mediators than just histamine, so if you can block the activation of these cells, I believe you will have a much more efficient therapy” (Boeckxstaens, 2021).
At One End of the Spectrum is IBS, at the Other is a Food Allergy
Understanding that the immune response to a food antigen is local, as in IBS, whereas at the other end of the spectrum there is a food allergy. A more generalised food allergy condition sees a severe mast cell activation impacting upon breathing, blood pressure, swelling, skin issues like itching or hives, and runny nose etc. Professor Boeckxstaens highlights this idea of the spectrum as a way forward in understanding our biological mechanisms and more successful treatments for IBS.
On this basis, from the findings of this research, it can be speculated that it is quite likely that many people are operating under the false premise that they are allergic to certain foods when they are not. Rather, they have developed a localised gut immune reaction to foods like wheat, gluten, cow milk etc when these foods were present at the time of gastrointestinal infection. Their intestine then associates this food with the infection and produces histamines which cause abdominal pain. True immunoglobulin (Ig) E- mediated food allergies are rare in those suffering from IBS. “The majority of patients who believe they are wheat intolerant are not actually sensitive to wheat on objective, double-blind, food-challenge testing” (Talley, 2021).
What is the Role of Mast Cells in the Pathogenesis of IBS?
According to Professor Nicholas Talley of the University of Newcastle in NSW controversy remains in regard to mast cells and their role in how IBS develops as a disease. Reported increases in mast cells have been limited to the subset of IBS patients with diarrhoea predominant IBS. There are studies outside of this group that have failed to find increases for whatever reason. Talley states that it is unclear whether this is due to methodologic limitations or other factors. In his own research he and his colleagues have demonstrated increased mast cells in the small intestines of patients with IBS. Interestingly, both mast cells and the microbiome can release histamine. Talley reports that new evidence has emerged that blocking histamine in IBS can be an effective therapeutic treatment for some sufferers.
Different Types of IBS
IBS-D refers to Diarrhoea dominant IBS, whereas IBS-C is the Constipation dominant form of IBS. Current scientific thinking links IBS-D to food allergens in its pathogenesis. IBS-C is thought to have a different developmental cause.
Antihistamines: Help or Hinderance?
Antihistamines have been around for quite a while and have been employed by allergy sufferers in their battle with environmental challenges to their health. First generation antihistamines were fairly noxious substances with the sedating side effects often outweighing the benefits in the first place. Next generation antihistamines have been