El eje intestino-cerebro

La relación entre el intestino y el cerebro es algo que se está investigando en la actualidad, pero hemos sabido “desde siempre” que hay una relación entre estas dos partes. ¿Habéis conocido a alguien que cuando está de exámenes se le suelten las tripas? ¿Quizás has sentido alguna vez “mariposas en el estómago”? ¿O has tenido “el estómago cerrado” antes de una entrevista?

Las personas que padecen síndrome del intestino irritable tienden a tener digestiones pesadas, se sienten muy hinchados y son más susceptibles a padecer diarrea o estreñimiento. Estas personas también tienden a padecer más ansiedad y depresión que la media. Cuando el intestino está irritado, puede hacer nuestra vida de lo más desagradable. Y puede ocasionar una micro-inflamación del intestino, que tengamos mala flora intestinal o incluso intolerancias alimentarias. 

Es muy frustrante para estos pacientes ya que, al no haber pruebas, se les considera hipocondríacos o exagerados. El estrés es uno de los desencadenantes más conocidos y aceptados hasta el momento. 

Una de las teorías sobre el funcionamiento del eje cerebro-intestino bajo estrés es ésta: las circunstancias estresantes producen un ambiente más propicio para el desarrollo de ciertas bacterias (bacterias que en períodos de estrés no están o están en menos cantidad). Esto significa que, incluso cuando la situación estresante llega a su fin, podríamos seguir sufriendo los efectos de este cambio en la flora intestinal.

Quizás esto influirá a nivel cerebral la próxima vez que tengamos que hablar en público, y nuestro cerebro recordará lo que le pasó al intestino y lo mal que nos sentimos aquella vez. De hecho, un estudio hecho en dos especies distintas de ratones, una más tímida y la otra más atrevida, demostró que intercambiando la microbiota entre las cepas, su comportamiento también varió. La cepa normalmente más tímida se volvió más atrevida y viceversa. 

¿Puede regular hasta cierto punto nuestro comportamiento nuestra microbiota?

Diagnosis of IBS: Breath Tests

One of the many frustrating aspects of irritable bowel syndrome (IBS) is it can appear quite vague and “un-scientific” when it comes to getting a diagnosis. In today’s modern world we expect diseases to be diagnosed rapidly and efficiently, we go to the Drs, they take some blood and a few days later we have our results. With IBS on the other hand, its lots of questionnaires, symptom diaries and trial and error.

One area that does appear, on the face of it, to offer a clear yes/no answer are breath tests. But how useful are breath tests when it comes to an IBS diagnosis?

What are breath tests?

Breath tests are used to determine whether you absorb or malabsorb a particular sugar. The tests offered are usually for lactose, fructose, sorbitol and mannitol. The patient will be given a dose of one the above sugars and then the amount of hydrogen and/or methane is measured in the patient’s breath. The understanding is that any of the sugars that are not absorbed are fermented by intestinal bacteria which produce the gases hydrogen and methane. The gases are carried in the bloodstream to the lungs where they are exhaled. A cut off point is established and if the amount of exhaled gas is above that point then the patient is diagnosed as “intolerant” to that sugar.

For an individual that suspects they may have IBS these tests appear very attractive because all of the mentioned sugars are associated with the condition plus the tests promise a quick and clear result.

But…..

Sadly here comes the but. While lactose intolerance is a recognised condition and the breath test to determine it well established, the same cannot be said for fructose, sorbitol and mannitol. One issue is the lack of standardisation of the test, different centres have different cut-off points so your diagnosis may be different depending on the centre’s cut-off point not the amount of hydrogen you produced in your test.

Focussing on fructose for a second, we all have a limited capacity to absorb fructose. That means that at a large enough dose every single one of us will malabsorb fructose. A study from way back in 1986 found that 8 out 10 healthy subjects malabsrobed a 50g dose of fructose, whereas only 1 out of the 10 malabsorbed the 15g dose (1). Another study in 2014 found similar results, in a group of 16 healthy (non IBS) participants, a 40g dose of fructose was shown to distend the small bowel with water and cause IBS type symptoms even though they were not IBS sufferers (2).

This means that depending on what dose they give you could be wrongly labelled as intolerant to fructose or even given a false IBS diagnosis. What has been shown is that some people are more sensitive than others to a single dose of fructose but to label them intolerant is probably an exaggeration.

In conclusion, while the idea of a quick test and diagnosis is very attractive, especially in a condition such as IBS where patients are usually desperate for a straight answer. The lack of standardisation of the tests and the fact that we all could be diagnosed as fructose “intolerant” at the right dose means that sadly breath tests are not a reliable way to get an IBS diagnosis.

References

1.  J J Rumessen and E Gudmand-Høyer, 1986. Absorption capacity of fructose in healthy adults. Comparison with sucrose and its constituent monosaccharides.Gut. 27 (10) 1161-1168

2.  Murray, K et al. 2014. Differential effects of FODMAPs (fermentable oligo-, di-, mono-saccharides and polyols) on small and large intestinal contents in healthy subjects shown by MRI. American Journal of Gastroenterology. 109 (1) 109-110

Gluten Sensitivity: Does it really exist?

In previous articles we have explained the difference between coeliac disease, wheat allergy and a third condition known as Non-Coeliac Gluten Sensitivity (NCGS). To briefly recap, as the name suggests, NCGS appears to be a condition where people who are neither coeliac nor allergic to wheat still report symptoms of bloating, loose stools etc. when consuming gluten containing foods. The mechanisms behind the condition are unclear, the immune system doesn’t appear to be involved but some researchers have suggested that NCGS may be a step along the path towards coeliac disease (1). Whilst we were completing the Monash FODMAP course another possible explanation was put forward to explain why people who have no immunological response to gluten still report gastrointestinal issues when eating gluten containing foods. What was interesting was that the explanation called into question the very existence of the condition of NCGS.

In recent years gluten free eating has become very popular and lots of pseudo-conditions are attributed to gluten. Although NCGS isn’t what we would call a pseudo-condition it has been proposed that it might be part of IBS and the culprit isn’t gluten after all. 

Fructans are chains of varying length of the sugar fructose, they are universally malabsorbed because we do not have the required enzyme in our body to break the chains into smaller fructose units. This leads to the fructans passing to the large intestine where they are fermented by the resident bacteria. This fermentation and the resulting gas production is usually well tolerated by non-IBS people but people with IBS tend to be highly sensitive to the fermentation of fructans and experience painful bloating and bowel distention. Foods that contain fructans are vegetables such as onion and garlic and of course wheat.

Monash University state that there is a lack of evidence that has managed to separate the effects of gluten from fructans so it is unclear which food component they are reacting to. Therefore, they do not recognise NCGS as a condition in itself and propose that people who report problems with gluten may in fact be IBS sufferers reacting to the fructans in wheat (2).

Now, this all sounds well and good, people can now relax and realise they weren’t sensitive to gluten after all. However, the problem lies in the practicality of it all. Finding a food that contains gluten but no fructans is virtually impossible, the only one we have found so far is sourdough bread or “masa madre” as it’s known here in Spain. During the fermentation process of sourdough bread, microorganisms such as Lactobacilli feed on the fructans and reduce their content in the finished product. The end result is that people who previously thought they were gluten-sensitive could enjoy sourdough bread, providing coeliac disease has been correctly excluded.

In conclusion, it appears that there is a lack of strong evidence to declare that NCGS is a condition in itself and people who report symptoms may be in fact IBS sufferers who are particularly sensitive to fructans. Aside from wheat, people who suspect they may fall into this category also need to keep in mind, onion, garlic, leeks and chickpeas.

For any more information on IBS or the Low FODMAP diet please get in touch via info@gabinetederueda.es

References 

1. Francavilla MD, et al. 2014, Clinical, Serologic and Histologic Features of Gluten Sensitivity in Children. The Journal of Paediatrics; 164: 463-7

2. https://www.monashfodmap.com/blog/the-truth-behind-non-celiac-gluten/ 

¡Terminamos el curso de FODMAP de la universidad Monash!

Grandes noticias!! Hemos terminado la especialización del manejo del síndrome de intestino irritable (SII) tras completar el curso de la universidad Monash titulado “La Dieta Baja en FODMAP para Síndrome de Intestino Irritable”. 

La Universidad de Monash es el pionero en el manejo y tratamiento de SII con una dieta baja en carbohidratos rápidamente fermentables que se llaman “FODMAP”. Tras completar este curso podemos ofrecer un tratamiento basado en evidencia científica para personas que tienen problemas como dolor abdominal, gases e hinchazón. 

Si quieres saber más sobre la dieta FODMAP haz clic aquí o si crees que esta dieta te ayudaría escribanos en info@gabinetederueda.es